budworms cannabis

Budworms! Everything you need to know

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The aim of this thread is to teach people everything there is to know about the budworms that are attacking your plants. The common name of this insect is the Tobacco Budworm. It has a few other names that are synonymous but that one will lead you to the most relevant information in case you want to do further research.


The tobacco budworm varies greatly in appearance so it can easily be confused with other species. Making an accurate ID of your attacker can be important because some species have built up resistances to certain treatments. Luckily for us growers, if you find a caterpillar on your plants you can be 99% sure its a tobacco budworm. If you live in Africa, Europe, New Zealand, Australia or Asia its going to be the species Helicoverpa armigera. If you live anywhere else its going to be the species Heliothis virescens. The distinction between these two species is not important however since they can both be treated using the same methods.

Most people find the larval form (caterpillar) on their plants so I won’t spend much time describing the adult moth. The caterpillars are initially pale green and often have black dots covering their body. Thin dark lines run down the length of the abdomen and tend to be darker around the second and third segments. As the larva ages (progresses in instars) the black dots may develop a red border around them. The abdomen is also covered with numerous microspines that give the caterpillar a rough feel. The head capsule is nearly always a light brown color. Again I wouldn’t worry too much if this description doesn’t completely match up with the caterpillar you find. There is great phenotypic variation in the tobacco budworm so there can be different colors and designs.

The tobacco budworm goes through an egg, larvae, pupae and adult moth stage. This is important to know so that you can realize where all potential dangers lie. Eggs are spherical and white to yellowish in color. They are about 5mm in diameter so it can be difficult to spot them. An adult female moth can lay more than 500 eggs so this is a huge problem! This problem made even worse if growing indoors since the conditions are perfect for the speedy development of the eggs and larvae. Eggs can hatch anywhere from three to 14 days after being laid. Indoors, you can expect them to hatch closer to the three day range. If possible the moth will lay these eggs close to the reproductive tissue of the host plant (our precious buds).

When the caterpillar has developed through all six of its instars (phases of growth) it will burrow 1-7 inches into the soil and begin to pupate. Don’t let this happen! It will probably take 15-30 days for a caterpillar to mature so you have plenty of time to keep a look out for these things. Keep in mind though that when the caterpillars are very young they are only a few centimeters long and will be similar in color to the plant. Regardless of how vigilant you may be, never reuse soil that was involved in an infestation. Keep bags of unused soil closed so budworms don’t develop secretly and surprise you in the next grow.

The adult moth is a light brown color. The banding on the wings is different depending which species you’re talking about but just to be safe kill any moths that make it into your grow room.

As with many other problems, the best method of managing these pests is to prevent them from entering into your grow space in the first place. Do don’t bring anything from outside into your indoor grow. This includes soil, pots, gloves, clothing thats been touched by wild vegetation and ANYTHING else. Any of these items could be carrying eggs.

If you have an outdoor grow or you failed to keep your indoor grow pest free and you come under attack from the budworm there is still hope! Bt insecticide can save the crop as long as you act quickly. This insecticide is actually a bunch of tiny bacteria! Bt stands for Bacillus thuringiensis, a bacterium that produces a protein deadly to the tobacco budworm. The protein interacts with a intestinal lining of the caterpillar, paralyzing its digestive system and preventing it from eating. This will take effect in a few hours after ingestion. Notice I said ingesting and not contact. This is your biggest problem as it will require frequent applications of the insecticide. If the budworms have burrowed deep into your dense buds they will continue happy munching on your plant without eating any of the bacteria. Combat this by physically checking each bud site for holes (I know its a bitch). Pick out the bastards in the evening hours when they are least active. Spray your Bt all over the plant until it is dripping and pray you get them all. Since the bacteria must be ingested ONLY the larvae are vulnerable and that is the reason you must keep applying the insecticide. Eggs must hatch before they can be killed. Adults and pupae should be killed manually if found.

On a side note, if you are growing outdoors and are conscientious of the environment around you (as you should be), you don’t need to worry about harming any nontarget organisms with the use of Bt. It specifically attacks caterpillars like the budworm and nothing else.

Releasing natural predators into your grow room can also serve as a secondary method of eradication. Some wasps, the bigeye bug, damsel bugs, minute pirate bugs and spiders are known predators. I’ve heard that ladybugs and praying manta can also help.

The aim of this thread is to teach people everything there is to know about the budworms that are attacking your plants. The common name of this insect is…

Caterpillars on Marijuana Plants

Carterpillar of bright colours

During the outdoor marijuana growing season there are many insects that feed on our marijuana plants.

In this case we will discuss one of the more voracious predators for cannabis plants, which leaves them totally shattered and useless for their consumption, caterpillars.

What is a caterpillar?

Caterpillars are the larvae of insects of the Lepidoptera family, more known after their metamorphosis into beautiful butterflies. There are many species of butterflies that can be found all over the world so there will also be many types of different caterpillars, with different colours and sizes but with clear characteristics in common, such as a segmented body, their 6 legs or the hooks of their false legs.

Before finding a caterpillar in our marijuana plants, we’ll see how the butterflies lay down on the buds or leafs, usually in the highest parts where the biggest and unattainable buds are located. Butterflies generally deposit their eggs prior to the arrival of the winter season, so these eggs will hatch when ambient temperatures are the appropriate, needing the heat of the end of summer, which coincides with the arrival of winter in about two months. It is very feasible that butterflies deposit their eggs and these don’t hatch until appropriate conditions prevail.

Where is the caterpillar?

Caterpillars have a long body divided in segments of different colours, generally adapted to camouflage themselves among the vegetation, avoiding this way to be eaten by birds or other natural predators of these insects. They move using their 6 main legs along with 10 false legs distributed throughout their body, which can be located in different parts according to the type of Caterpillar.

These voracious predators of green matter don?t breathe through their mouth but through a few small holes that are scattered throughout their, called spiracles. These holes lead to an internal network of interconnected tubes or trachea which provide the oxygen directly to the cells, being a very effective and spectacular respiratory system.

Their senses, such as sight, smell . aren?t highly developed; their sight is very reduced and limited, and it is composed of 6 small eyes distributed across the face in the shape of a horseshoe, located in the lower part of the head. Their antennas are used to detect food, using their powerful jaws to quickly devour leafs, buds, small stems etc.

How to detect the attack of caterpillars on marijuana plants?

We have explained that butterflies leave their eggs on the leafs of plants, but we haven’t mentioned that these leafs will be the first vital sustenance for newly born caterpillars. It should be noted that not all caterpillars prefer the same type of leafs, so we can find different types of caterpillars on cannabis, but we will usually find the same type of caterpillars , belonging to the same species, if we cultivate in the same geographic location.

First of all, we must thoroughly observe the plant, looking at those leaves or buds that are found in the highest parts of the plants, where butterflies lay their eggs. At first sight it?s really complicated to be able to see the eggs, but if we carefully examine the plant they will be distinguished as small sets of dots that acquire different colours (white/yellow) and shapes (round or oval), depending on the type of butterfly egg.

After this initial inspection – and during the whole flowering period – we must look at the buds, starting at the top and thoroughly examining the rest of the plant in search of small black remains or darker parts of the buds, which are sign of rottenness. The first attacked flowers are the bigger ones, but without being extremely compact, so caterpillars can easily pierce them and devour the softer tissues, such as the small branches of the lower parts of the buds.

In the case of finding a caterpillar, we should make a daily inspection of the whole plant, especially on those hours when the Sun is low and the ambient humidity is high, although it is very easy to find them on the rest of the day, eating nonstop, as their hunger is insatiable and voracious.

Bud bitten by a Caterpillar

How to prevent or eradicate caterpillar pests?

After an exhaustive search in our plants – and if a caterpillar is detected or if we observe any bitten bud -we should apply a product that repels or kills the eggs and larvae of butterflies.

These products are generally created on the basis of a gram-positive bacillus – such as Cordalene – that is naturally found in the soil and also on plants. Such products are specifically created to treat lepidoptera larvae plagues, being more or less effective depending on the type of larvae to treat, but always offering great results.

We can also treat the plants with broad-spectrum products to control caterpillars apart from other possible pests that can occur at the same time, in this case we could apply Mittel Concentrate in a dosage of 1 ml/l. When the butterfly larvae eat the vegetable matter treated with these product, they will intoxicate and die, leaving the plant free of intruders.

Eradicate Caterpillar by hand

Another product with which we can treat caterpillars and other types of insects – sucking insects – is Pireprot , which contains pyrethrins as active ingredient, acting by contact and leaving cannabis plants free of insects. In this case, caterpillars would be removed from the plants leaving them clean to continue flowering without mishaps.

It should be noted that all the above-mentioned products are bio-degradable and biological, so they can be used several times when required as a preventative or to eradicate Caterpillar plagues. The security period is relatively short but it?s recommended – and important – not to apply the product during the last 15 days before harvesting the cannabis plant to give time to the treatment to not leave traces of the product in the buds.

Fermented Caterpillar depositions provoke Botrytis

Plague of Caterpillar just bevore the harvest

In the case that the plague appears in these last 15 days we have to carefully observe the plants every day, opening the buds to see if caterpillars are hidden inside the flowers.

If we don?t proceed this way it?s very possible to harvest the plants with the larger buds clearly affected or even to throw them away because of caterpillars bites and defecations, which cause the appearance of fungi like botrytis.

In the case of having the plants affected by botrytis, you can treat them as long as you can leave a security period of 15 days before harvesting the plants. If the end of the flowering stage is near, the best will be to look at the state of the trichomes and – if these are mature enough – harvest the plants.

Once harvested, we should instantly proceed to remove the infected parts from the healthy ones. If we do not separate these parts infected with fungus this will extend to end up rotting the whole bud, even during the drying phase, as it requires a few days to lose much of the humidity contained in its metabolism.

Precautions post-harvest for the caterpillars

Macro of a Caterpillar devouring a bud

After harvesting the marijuana plants we should hang the plants upside down to perform a proper drying of the cannabis buds. In this way, plants lose their humidity and stop being a good hideout for those caterpillars that have been able to survive the purge realized by hand.

These caterpillars will leave the plant to be able to become butterflies, so when plants are dried, we?ll be able to see the caterpillars sliding down from the bud making rappel until arriving to the ground.

Once arrived to the ground, they will quickly seek another vital sustenance to be able to feed and continue their vital process, so it?s important to recover these caterpillars to prevent that they fill our house with cocoons and later with butterflies, as they embed in the most unlikely and generally inaccessible places.

Recommendations for a crop without caterpillars:

  • Locate the butterflies that lay down on the plants.
  • Look for eggs on the leafs.
  • During the flowering phase, control the buds looking for signs of bites.
  • In case of detection, apply Biothur or another product against caterpillars.
  • Stop applying the product within the last 15 days.
  • Review the plants and buds after harvest and remove the infected or bitten parts.
  • Capture the caterpillars by hand in the case of not being able to apply the product.

Common caterpillar on cannabis plants

Related Posts

Drying and curing marijuana buds

How to control Whiteflies on marijuana plants

How to combat aphids on marijuana plants

Powdery Mildew fungus on marijuana plants

Micronutrients and Marijuana plants

Comments in “Caterpillars on Marijuana Plants” (28)

Star 2020-10-01
I have two plants that are 8 week and one that is 9 week they are in the beginning of 8 wks and I found a worm and afids are trying to hang out I have done nothing but water was told by people to just keep it simple for our first time growing out doors should I just pull them before it becomes more of a problem.?

Tim Alchimia 2020-10-02
Hi Star, thanks for your comment and question. At this stage (8-9 weeks) I’d guess that the plants are probably more or less ready to harvest so if you feel that the pests are getting too much then yes, by all means, go for it! I would, however, recommend trying to remove all the caterpillars by hand before you chop the plants, as they will carry on eating and pooping in your buds as they dry, causing them to rot from the inside out. The best thing you can do is to get rid of them ASAP whether you decide to harvest early or not. I hope that helps, best wishes and happy growing!

Rachel 2020-09-22
I am searching the entire web for a natural bug spray during late flower, I’m at 6 weeks and came across tomato leaf spray but cannot find anywhere if it’s safe to spray the whole plant, buds and all, or just the leaves? The plant is moderately infested mainly with aphids but mites and caterpillars as well. Any advice would be greatly appreciated. Thank you

Tim Alchimia 2020-09-23
Hi Rachel, thanks for your comment and question. It’s a tough call and a lot depends on how much longer you expect to flower the plants for. You’re at week 6, and if it’s an 8-week plant then there’s not much time left to safely spray anything before harvesting. If, however, it’s a 10+ week plant then yes, there are a few options, although the best all-round product would be Neudorf Spruzit Mittel, being the only product capable of dealing with all the pests you mention but, as you can see in the description, it is not recommended for use in the last 15 days before harvest. Alternatively, you can spray some Bacillus Thuringiensis to deal with the caterpillars, but it won’t have any effect on the aphids or mites. You could try simply spraying them off with water, but this may lead to fungal issues with the flowers if they get too wet. Some growers even go as far as wiping down each individual leaf to get rid of pests without applying any products to the buds themselves. If you grow indoors with added CO2 then a great way to kill the pests safely is to increase CO2 levels to the maximum for a few hours, which will kill the bugs without leaving any harmful pesticide residue. I hope that helps, best of luck for the rest of the grow!

Nightlight 2020-09-08
Bacillus Thuringiensis (Monterey brand) outdoor grow in sunlight (no plastic top/directly outdoor) is it normally do not use 14 days before harvest on marijuna? i saw a post that said “breaks down in UV in 4 days” then another post u said stop using 14 days before harvest. the catepillars got to my lasts outdoor auto flowers and now i’m seeing on my larger photoperiod chewing holes in leaves, some early bortritis. guessing 8-11 days on one left to harvest, 13+ on 2 others. a few days will be 98F then 2 weeks of 84F if temp is a factor. thank you! wish liquid drugs (alcohol were illegal and natural plants were legal so i could send u some!) thank you!

Tim Alchimia 2020-09-09
Hi Nightlight, thanks for your comment. Believe me when I say that I share your opinion of the legal situation regarding cannabis. it’s insane and injust! As for the caterpillars, I’m sorry to hear yoy’ve been having issues there. Personally I would probably listen to the guidelines and stop applying BT around 14 days or so before harvest, mainly because it has quite a distinctive smell (at least the brands I always used do, anyway), and it’s not something I want on my buds when I’m consuming them! It’s true that the bacteria, as far as I know, is harmless to humans and will break down in UV light, but the bacillus itself usually only makes up anything from 15% to 50% of the weight of the ingredients in the powder, the rest being carriers or fillers to bulk up the powder and facilitate its spraying and spreading. These will remain on your plants unless the rain washes them off. Another reason not to spray late in the season is that BT is only effective against the very smallest caterpillars, in the few days after emerging from their eggs, so by this stage, I’d guess that the grubs themselves may be too large to be affected. You could probably safely spray the plants that have 13+ days left, but anything less than that and I’d be hand-picking the grubs and their poop out of the flowers rather than spraying anything. better safe than sorry! I hope that helps, best wishes for the rest of the season, happy harvests!

warrenlj 2020-07-04
I live in norcal and have been having problems with caterpillars the last couple of years. I’m wondering if using BT regularly would benefit by the water curing method? New to this BT and water curing.

Tim Alchimia 2020-07-06
Hi Warren, thanks for your comment. I can highly recommend BT as a preventive treatment for caterpillars as it is organic, safe for humans and animals and breaks down in sunlight after 4 days or so. This ought to mean that washing it away with a water cure would be unnecessary, however, I don’t see that there’d be any harm in trying it for the sake of experimenting if that’s something you’re interested in. Personally I’ve never tried water curing and I’m not sure that I know anyone who has either. I’ve heard it produces a really smooth smoke but I can’t imagine it’s doing the terpenes any favours at all! I’d say that if you’ve grown the weed really well then there shouldn’t be any need to do anything other than a regular cure and dry. I hope that helps, best wishes and happy growing!

Sophie 2020-05-08
what’s the name of the first caterpillar (the red one)?

Tim Alchimia 2020-05-11
Hi Sophie, thanks for your question but I’m afraid we’ve no idea about the species of butterfly or moth that produces such a beautiful caterpillar. Sorry that we can’t help you but maybe you could try an insect identification website? All the best and happy growing!

Artdowg67 2020-04-21
Great collection of information regarding these little bugs. Knowledge being the power it is, we can only get better as we go. Thank you to the webmaster of this page, as knowledge is usually the best thing to have.

Tim Alchimia 2020-04-22
Hey, thanks for the comment, you’re right. knowledge is power and we’re all about giving power to the people! All the best and happy growing!

Kirsten Fox 2018-10-18
I was just wondering if anybody has tried smoking them out , like lighting a piece of paper on fire , then blow it out and wave the smoke under your branches and see if the little suckers will come out that way ? Have you ever tried that or would it just ruin your plant ?

Ann 2018-10-06
I have had the little green catepillars in every grow. Some years worse than others. I don’t use chems. Lost coast plant therapy will kill the larvae and not hurt the birds. If you can attract the little black capped chickadees to your grow they will wreak havoc on the catepillars, chickadees love catepillars and they are always around my grow. I have been examining the buds daily and plucking the ones that the chickadees missed.

Vic Patel 2018-09-11
That green thing looks exactly like a caterpillar that was eating my California Blue Bells. From what I read they pretty much eat anything, its a moth caterpillar, English something.

C. Steele 2018-08-31
I grew in Maine for 20 years before moving to Southern Cal so didn’t have the same pest problems that exist here. The moths that lay eggs that grow into green bud eating caterpillars are the most destructive. They seem to lay eggs on the largest buds located on the tallest part of the plant. Once you start seeing damage, i.e. dead brown areas that quickly begin to mold, you are already infested and there are probably tons of them. I’ve tried netting, it helps significantly but its not fool proof and I’ve never been able to prevent all of the egg laying moths from getting to the plants somehow. Spraying with Bacillus Thuringiensis (Monterey B.T.) at start of flowering, every 5-8 days, at dusk, RELIGIOUSLY, right up to a week or so before harvest resulted in the least amount of caterpillar damage in my four seasons growing outside. I read that the live bacteria digests the eggs before they can grow into a leaf eater. You can’t grow outside around here without taking extensive steps to deter the numerous pests that attack Cannabis. The whole health of the plant is effected by seemingly minor pest activity. Stressed plants don’t grow like happy plants, there is a BIG difference. I took me years to get my dark green thumb. I spend a couple hours in my gardens and I still learn new things all the time. You need two green thumbs and a bunch of expensive biological weapons to succeed cultivating Cannabis outdoors here in Southern Cal. it is not as problematic a crop in other places but here it certainly can be a challenge one that even an experienced grower can struggle with. There were less avenues to failure cultivating back in Maine, I would have given up if I first started out here. Spraying mature flowers with a water solution at night should generally be avoided, the practice is just asking for mold issues, especially if inside a green house environment. Mold was more problematic in Maine where wet weather regularly continues for days and the higher humidity and cold nights can prevent tight maturing buds from being able to completely dry (externally) creating conditions for mold to explode. During the last 2 weeks of flowering wet weather can result in complete loss from mold. Once it starts, it will spread quickly and continue to ruin all your hard work even while hanging inside to dry. I used “Nuke Em” last year which claims to help prevent mold from starting and spreading, its organic and can be applied right up until harvest day. The label claims effective against all kinds of pests like spider-mites and caterpillars but I don’t have any personal experience using it in that capacity. The only active ingredient is citric acid, you can use some PH down to basically do the same thing and save yourself some $, I paid $55 at a grow shop for 1 quart of Nuke ’em, don’t know if it was all that.

Serious420 2018-06-28
From my experience over the years netting “Helps” some. But where there is a will there is always a way. I have seen on many occasions where the moth/butterfly will lay its eggs in the netting and once it hatches drop directly onto your plants waiting below. You must check your netting regularly. Also as noted above the caterpillars themselves are migratory. Meaning that they will crawl along the ground and under any loosely applied netting to get to your plants! All in all it is far better to go all in when try to prevent caterpillar attacks. They sure go all in trying to get to them!

Paul Dillan 2018-06-21
Great information, thank you.

Robert Burns 2017-11-07
Those are mother caterpillars. I have never found a butterfly caterpillar on my cannabis plants. Moths fly at dusk and at night. You chemical approach turns me off; I’m tired of Big Ag. Cut the chemicals and screen out the pests. Also, drying the plants is extremely counterproductive if infested, because the caterpillars continue to eat and grow until the plants are too dry just as they do at the end of their season in the desert when plants are drying up.

Tim Alchimia 2017-11-10
Hi Robert, thanks for your input. In different parts of the world butterflies can be a problem, while in other parts there are more problems with moths, but that’s by the by, whether they’re butterfly or moth caterpillars the approach is the same, we’re growers not lepidopterists! We’re not exactly fans of Big Ag either, so of the three solutions we’ve given, all three are 100% organic: Cordalene is based on Bacillus Thurigenesis, a naturaly ocurring bacterial inoculant that kills young caterpillars; while Mittel and Pyreprot are based on Pyrethrin, a naturally occurring pesticide sourced from chrysanthemum flowers. All totally safe and non-toxic to humans. We definitely wouldn’t recommend cutting and hanging the plant to dry if it’s still infested, of course not! The idea is to remove the pests, and then harvest and dry the plant to avoid the appearance of mould due to the caterpillar damage, and hopefully save the crop from loss. Thanks again for your comment, I hope that’s cleared things up for you, all the best!

Mitch 2017-10-01
I’m probably a week or two away from harvesting my Blue Dream, and just saw that the caterpillars have now taken up residence there and are already munching and destroying. Can anyone tell me if I’m far enough away to be able to hit it with Botryprot without negatively affecting the end result?

Tim Alchimia 2017-10-02
Hi Mitch, Sorry to hear about your caterpillar problem, I’d recommend that next time you spray preventively with Bacillus Thuringiensis every ten days from pre-flower stage up to two weeks before harvest to avoid this invasion. According to the manufacturer, Botryprot has a safety period of 15 days so if you’re harvesting in two weeks then that should be fine, but not if you’re planning to chop the plants any earlier. In your position I would pick out the caterpillars by hand and remove any of their poo and rotten bud around it. Then I’d spray very locally with Aptus Fungone to stop the mould spreading further. Good luck, I hope you manage to save your buds, happy harvesting!

Mitch 2017-09-30
I live in the San Francisco area, where the temperature between day and night can fluctuate as much as 30 degrees during this time of year (and the cool temps plus fog is a real problem if one is trying to prevent bud rot). I only have three plants (2 Gorilla Glue and 1 Blue Dream), and only recently discovered caterpillars dining on my beautiful crop. I now spend around 45 minutes per plant per day gently separating the bud leaves, looking for either caterpillars or their telltale brownish rotted leaves their munching creates, pluck the rot, then use a toothpick to remove the caterpillars and toss them FAR away from my girls (I can’t bring myself to squish ’em; I believe that their instincts should not be punished). So far, I’ve thankfully only found them on the Gorilla Glues, but I’m guessing that won’t last. I’m toying with the idea of harvesting early, as my GG ‘chromes have just begun to turn amber (only around 10% of them have turned, so this would definitely be early); on the other hand, as long as I’m as diligent as I have been for the past two weeks, then although they’ve now decimated at least 50% of my cola tops (they seem to enjoy going for the largest, juiciest buds they can find, and those are of course usually at the top of the colas), I might be able to keep them alive and relatively uneaten (and hopefully as rot-free as possible) for another week or so. My other issue is spider mites and their webbing, and although I used NukeEm successfully, the mites have now come back, and I’m wondering whether to give them one more spray before harvest (NukeEm is organic and turns inert after 48 hours, so should be fine as long as the plants are well-flushed before harvesting. but I want to NOT water them for a few days before chopping, so this has become a conundrum). Thoughts?

Dani Alchimia 2017-10-02
Hi Mitch, If your GG plants are one week away from harvest, I’d try to harvest them asap, especially if you also have spider mites. It’s not the ideal situation, but I’ve thrown away so many buds for waiting too much that I’ve learned the lesson. You can try to remove the spider mites manually with a sponge or something similar (also remove any fan leave infected by mites), but I would not risk the whole crop for having a few more amber trichs. (I’m not a fan of spraying plants soon before harvest). Best!

Kathy 2017-09-09
Get some chickens

Tim Alchimia 2017-09-12
Hi Kathy, thanks for your suggestion, however I’ve seen chickens do some really devastating damage to cannabis plants before, leaving them completely leafless! Once they get the taste for it they don’t stop! I love chickens, I keep them myself and they’re great to have around the plants to eat pests and for their small manure deposits, but it’s absolutely essential to protect the plants from them, they can be so destructive! All the best!

Kenny 2017-08-30
These guys have devastated all three of my plants this year. This is my first time growing in 30 years (now legal here) and Im not sure I was prepared for an insect that could do the kind of damage these lil critters dish out. Learned a good lesson in backyard growing but it cost me about 1/3 of my harvest. Thanks for the great info on fighting back against these guys next season.

Tim Alchimia 2017-08-30
Hi Kenny, thanks for your comment, I’m sorry to hear about the devastation to your crops, I’m glad at least that you’ve managed to save some though, that in itself is an achievement! So next year you now know to start early in the season with treatments of a product containing Bacillus Thuringiensis (BT), applying every 8-10 days to coincide with the life cycle of the caterpillars and to make sure you get them when they’re young for the greatest effect. Another thing to look into is the idea of releasing predators like Chalcid or Braconid wasps into your garden, these insects parasitise and lay their eggs on caterpillars, and can be an additional, very effective control method to use alongside BT as part of a pest management programme. Enjoy your harvest and best of luck for next season, happy growing!

David 2017-07-27
I was admiring the pretty butterfly this morning. He came to visit the top branch of my plant. Then, he flew away. Oh boy! I want to , ah, prevent this from happening!

Tim 2017-07-31
Hi David, I’m not sure I fully understand your question. however, if you want the butterfly to visit your plants, maybe try planting some butterfly-friendly flowers nearby to attract them, but if you want to keep the butterflies from landing on your plants, I’m afraid the only option is to use some kind of netting to cover them. I hope that helps!

Robert Burns 2017-07-18
PS: Reading online it appears that my greatest problem is with the budworm “Helicoverpa armigera, H. zea (Noctuidae)” or some other type of budworm. I found this in LEGAL PEST MANAGEMENT PRACTICES FOR MARIJUANA GROWERS IN CALIFORNIA put out by Department of Pesticide Regulation as the only pest warranting mention for attacking buds: budworms Helicoverpa armigera, H. zea (Noctuidae) Eat flowering buds  Shake plants to dislodge larvae  Remove infested buds  Plant corn as trap crop

Dani Alchimia 2017-07-18
Hi Robert, Thanks for your interesting comment! I know some guys who build cages for their plants made of anti-thrip netting, kind of green houses but with netting instead of plastic. It works great, you wouldn’t find a single caterpillar! Best!

Robert Burns 2017-07-18
I started growing for personal use after a lull of 40 years. I have been finding 3 types of caterpillars, loopers looking like they ate Viagra, solid green ones, and ones with bands of green all relatively small but today I learned that they have long been in my buds and that their visible symptoms there are not eaten leaves (because what’s eaten is not often visible outside the buds) but browning spots and (to a far lesser extent) caterpillar poop. I actually raise butterfly caterpillars (these are from small flying-rat moths) and so I pluck and chuck them when not enraged. There’s no way I’ll use “safe” insecticides or Dr. Frankenstein parasites or germ warfare, but with my new knowledge of bud damage I hope to minimize their wrath. I had feared mold which also has been a problem.

Tim 2017-07-18
Hi Robert, thanks for your comment. Sorry to hear you’re having trouble with caterpillars. By far the best remedy is prevention, and I’m afraid it involves using what you refer to as “Dr Frankenstein germ warfare”!! Experienced gardeners start using an organic preventative spray of Bacillus Thuringiensis early in the season. It’s a naturally occurring bacteria that destroys the guts of young caterpillars, but is non-toxic in humans. It won’t work properly once the budworms are fully grown, so it’s important to apply early and repeat applications frequently throughout the season. Your fear of fungal infection, however, is more than justified, as the poop left by the caterpillars will rot and as a result Botrytis is almost certain to attack the flowers, and by the time you notice the caterpillar damage, it may be too late, meaning preventive action on the caterpillars is best to ensure a high quality crop free from pathogens. If you only have a couple of plants, it may be possible to hand-pick all the caterpillars to remove them, but it’ll be difficult to get them all and you’ll need to deal with the potential mold problem using an organic solution such as Botryprot Best of luck, and happy harvesting!

Eros Shile 2016-11-25
It seems clear that at the exact second that the “green” culture is threatened by a butterfly, its “green” god become the green dollar bill. Need to get beyond that. When our land was “great” (e.g. before a billionaire mongol sat up offices to rule his kingdom, and quite some time before then), “weed” was everywhere and likely many species of butterfly, etc. counted on it. Cringing due to having “weed” confined and legislated so bad that crop loss due to how pretty butterflies reproducing effects our way of dealing and how we feel about common nature is a shame. Green should be green, through and through, and not Trump green.

Mithc 2016-10-17
I’ve discovered another one of my babies has been attacked partially by them. It’s is in at least it’s 7th week of flower if not 8th and all the stigmas have turned and began to draw up into the calyxes. And I’m thinking it’s probably best to go ahead and cut it. It’s over 8 ft and has great genetics so I’d hate to jeopardize any more bud to the infestation. My question is if I should just go ahead and harvest. I’d feel better if I could check my trichs but my loop is shattered and I live so far from town that I haven’t made it into town to replace it. And since it’s up to guess work with out it I thought maybe u could give me some advice. Thank you for any answer u might have and I really appreciate all the info u put up for ppl like me. It’s turned me from novice to pro in just a couple seasons and I now produce the best outdoor and indoor of anyone I’ve met in my area.

Dani Alchimia 2016-10-19
Hi Mithc, If you feel like they are a real threat to your plant, I’d harvest it as soon as possible. I don’t like to harvest my plants before I should, but if there is some risk of losing all the work done during the past months I’d just chop it and perhaps make some concentrate. All the best!

Mithc 2016-10-10
Caterpillars are by far my most hated enemy in my grows. I’ve had several 8 and 9 feet tall outdoor plants devoured and lost over half the year to mold and turds lol. Luckily they only got to 3 plants. And all because my wife kept leaving the porch light on. Arrrgh! Drawing moths. I finally took out the bulb and began plucking the bastards but it was too late? but caterpillars will actively hunt out your cannabis to feed on another adult moths and butterflies aren’t the only problem. It’s always possible for them to climb up onto ur plants from the ground if you don’t prevent it. Just another point that might help someone. I know I am preventing it now on my survivors by putting down stick traps for them trying to move to new plants

Dani Alchimia 2016-10-11
Hi Mithc, Yes, caterpillars can really be a pain in the neck. I’ve seen this year some people who build cages for their plants using insect netting, and it works great!! Thanks for your comment!

ravi.singh.GANJA 2016-05-29
Also look into butterfly & moth repellant or a net,so they can’t even land on the plants & lay there fukn eggs so no caterpillars I’m thinking about putting a net in my backyard to coverify my plants to avoid having them little fukers see how it works next season

Dani Alchimia 2016-06-06
Hi, Many people use nets to cover their plants and prevent caterpillars, it works great! All the best.

Flexy 2015-10-24
Oh man, those things are NASTY. We are about one/two weeks from harvest and just discovered some caterpillars, I found them since there were some rotten/brown spots on buds which I couldn’t explain. I first thought it’s bud rot from spraying or from the rain. Until I looked closer and saw the bastards. Now I did order Biothur but I guess it’s too late, will just have to pick them off by hand on those plants until harvest. I just picked two off and wife found another two just now. Always find really helpful stuff here on your blog by the way.

Dani Alchimia 2015-10-26
Hi Flexy, At least in Spain, and from what I’ve heard and seen this year, caterpillars have become a problem. As you mentioned, the rotten buds are typical symptoms of caterpillar attacks. As always happens with pests and diseases, normally prevention makes the difference. Next year, start spraying your plants before seeing any kind of symptom, especially during the pre-flowering stage of plants and the first weeks of bloom. All the best!

casey 2014-11-06
we just harvested our crop and discovered catapillars and I didn’t check before the bud and ended up smoking a catapillar what I want to know is are these bugs toxic in anyway

Dani Alchimia 2014-11-06
Hello Casey, Caterpillars eat our plants, so it all depends if our plants have toxic substances in them. If you made an organic crop, there’s no problem at all, since caterpillars are eating organic food and so have no toxic elements in their system. If you used some chemicals on your plants, caterpillars will also absorve them via their food; in this case, you will have the same type of substances in your plants and in the caterpillars that are eating them. Still, nothing to worry about. Don’t worry about your “accident”, but try to avoid it next time. Never smoked a caterpillar, but It has to be an experience. 😉 Thanks for your confidence Casey, Best vibes!

DD 4 NCD 2014-09-24
I harvested and have been plucking off these pesky little buggers. My concern is the crap they do doo on my buds. What does it resemble and is it toxic in any way? The plants really showed little signs of them while alive, but were very prevalent in the manicuring and now drying process. Now rolling into curing process as the moisture is getting depleted, I continue to rearrange and layer my buds in a large chest and continue to find smaller catapillars climbing out to find a new food source. Damn I hate outdoor growing except for the cheap light source. Let me know if you might have info on their little droppings I mentioned. DD

Dani 2014-09-25
Hello DD, Caterpillar frass is fairly inocuous, since it is composed by the green matter eaten by the caterpillar. This is why many growers don’t treat caterpillar pests with chemicals.(check google images for “caterpillar frass”) However, it is strange having them in your dried buds; maybe you stored them too early while they still had little moisture in them. Next time, try to hang your plants for some more days. Notice that certain strains are more prone to get caterpillar pests, so it is advisable to check which varieties will work better in your environment. If you know that caterpillars are common in your area, start treating your plants since the beginning of flowering, never wait to see them to start treating them. You are right about outdoor growing. we have the best possible light source. and free!! 😉 Thanks for your confidence, Best vibes!!

yolanda 2014-09-24
Can u harvest ur plants with little cattipillars I’ve sprayed and sprayed but still have a few IF was told to but in oven or free er over 130.c but my oven goes 170 only.plz help.I haverstef the plant see no more cattipillars but want to make sure there’s no eggs or very small catipillars

Dani 2014-09-25
Hello yolanda, If you harvest your plant with caterpillars in it, once the plant starts drying they will leave it looking for alive green matter to eat. You can see them rappeling down from your buds. What you need to do is looking for the appearance of fungus like Botrytis, often caused by caterpillar bites. If you see any dead part of the plant/bud, carefully remove it so the fungus doesn’t spread. Once the plant is properly dried, there should be no caterpillars in it. These bugs usually put their eggs on the leafs, so we propably won’t find any of them in our buds. A final visual exam of your dried buds before storing them is advisable. Thanks for your confidence, hope it helped!! Best vibes!!

In this post we present you one of the most devastating pests for the marijuana plants, the feared caterpillars which destroy the beautiful buds makin