Caterpillars On Marijuana Plants

April 21, 2021

Caterpillars love marijuana plants! Corn Borer and Hemp Borer are the two most destructive caterpillars. These pests will diminish the strength of your plant by eating away at the marrow inside the stalk causing stem cankers to form. If the plant is really infested it will break down.

Read this article and learn how to identify caterpillars on your marijuana plants and how to get rid of them.

Download my free Grow Bible to learn more about dealing with pests on your marijuana plants.

What’s even worse is that the hole Corn Borers carve into the stems creates an open doorway for other pests that will completely suck the life out of your marijuana plants. Hemp Borers will damage the buds (see picture).

Signs caterpillars cannabis

Stem boring caterpillars do their damage from the inside of the plant so, they can go undetected until it’s too late and the harm is done.

How to get rid of caterpillars

You can simply rely on nature to eradicate caterpillars by having parasitic wasps around. Mostly likely they will come all on their own as soon as the sense caterpillars are nearby. These wasps will lay eggs on the caterpillar’s body and when they hatch, the caterpillar becomes food for them.

Another way nature can assist you with this is the praying mantis. These insects love eating caterpillars and will remain until all of them are fully devoured.

Get rid caterpillars weed

When it comes to stem borers the only way to really get rid of them is to cut them out of the plant. If the plant doesn’t revive itself, then completely remove it by doing a clean cut at the bottom of the train. This will guarantee no further damage.

A complete plant defense system can help protect your crop from diseases and harmful pests. Grab our Plant Protector set today!

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Neem oil spray is excellent for caterpillar control. Use this once the sun has gone down or on an overcast day. The sun will make the solution useless. Spraying the tops and base of the plants. Don’t overdo it, just cover it really good.

Making your own neem oil spray is easy, just pour 1 to 1 ½ teaspoons liquid dish soap into one gallon of warm water. Pour in one ounce of neem oil and shake well. This concoction will lose its strength after 4-8 hours, so it’s pointless to keep what you don’t use. Do this once a week until all caterpillars are gone. You can buy neem oil at a nearby garden center or get it online at this link here.

List of marijuana plant symptoms

  • Holes with brown trails around them
  • Chew marks on the leaves
  • Yellowing on the top leaves
  • Holes and damage to the stems
Marijuana plant symptoms
Marijuana plant symptoms

Remember caterpillars are marijuana lovers! If you see any signs of these, you definitely want to do something about it immediately. These pests will destroy and potentially suck all the life out of your plant.

Plants with strong genetics have less chances of getting sick and are less vulnerable to pests and diseases. Make sure you buy weed seeds from a trusted seed bank.

Buy Marijuana Seeds

FAQs About Caterpillars on Cannabis Plants

What are some ways to eradicate caterpillars on cannabis plants?

Having parasitic wasps or a praying mantis around the plant, cutting the affected stems, or spraying with neem oil are some effective ways to deal with caterpillars on your weed plants.

How many caterpillars does it take to take down a marijuana plant?

All it takes is about five to ten caterpillars to demolish your plant.

What plant symptoms should I look out for to know that my plants have been infested with caterpillars?

Some of the most common caterpillar symptoms include chew marks on the leaves, holes and damage to the stems, and yellowing on the top leaves.

Practice and learning are all you need to grow marijuana like a pro! Let my blog help you get started.

Have you had caterpillars on your marijuana plants? Please share your experience or leave questions in the comments.

Happy growing!


The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]


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  1. By Marijuana Pests & Bugs – Control And Identification ,10 Jul 2015
    […] Unfortunately, even caterpillars that stay on the exterior of your plant can still ruin your crop. Caterpillars are strongly attracted to cannabis, and they will actively seek it out as a food source. Outdoors, you can get help from […]Read More
  2. By Symptom Checker – Identify Marijuana Plant Problems ,20 Jul 2015
    […] Caterpillars […]
  3. By Pests And Bug Control For Outdoor Marijuana Plants ,03 Aug 2015
    […] under control. The insects that you’ll want to pay the most attention to are slugs, snails, caterpillars, leaf-eating insects, and beetles. There are a few different means by which you can control these […]
  4. By John ,17 Sep 2015
    My plant is infested with baby caterpillars. They are eatin my crops & idk what to do.
    1. By Mike Cicchino ,20 Sep 2015
      Hey john, my plants were hit by caterpillar's as well! It has been a nightmare on the east coast this year, we are down about 7 inches of rain. We had many day's of temps in the mid to high […]Read More
  5. By Luv2gro ,20 Sep 2015
    I have had a terrible time with caterpillars in the past. This year I have been using Safer brand caterpillar killer...bacteria BT that targets only caterpillars. I apply in evening apx every 10 days...not a single caterpillar this season!!
    1. By Terrance Hirchag jr ,28 Jun 2018
      Whats the name of the product you are using to rid yourself of catapillars ???
  6. By latewood ,21 Sep 2015
    Best thing to do about "Caterpillars"; Immediately remove by hand. In some cases an insecticidal soap can work to stifle the production of further generations. It may take 2-3 applications, spread out over 304 weeks to catch up with larvae, […]Read More
    1. By Jay ,01 Sep 2020
      Hi! I noticed some bud-Rot developing at a lightning-fast pace on my plants the last week of August, and remembered my friend telling me that he had bud-caterpillars on his crop, and used Thuricide on them. I did some research, […]Read More
  7. By Stop Bud Rot On Marijuana Plants Now! ,01 Dec 2015
    […] your plants, their stems might have cracks that mold could travel through. Any damage caused by caterpillars, snails, worms, mildew, or other pests can also create a “tunnel” of sorts for gray mold to get […]
  8. By Art ,06 Jul 2016
    Last year I lost all four of my plants due to caterpillars damage. So this year I brought a mosquito netting to cover my plants. All six of my plants are budding nicely and no sign of caterpillars. YEAH!!!!!
  9. By Darcy ,23 Sep 2016
    Is it ok to use spinosad on flowering plants about to be harvested?
  10. By latewood.ILGM ,24 Sep 2016
    Spinosad is an ingredient in approximately 80% of all pesticides. When using a produvt such as Spinosad; It is advisable to read and follow the directions on the bottle. Each pesticide is different. If you cannot figure out from the […]Read More
    1. By latewood_ILGM ,02 Jul 2018
      Terrance. No you do not rinse off the neem oil. It will dissipate over time. I hope it all works out for you. Thanks for sharing. :)
  11. By J.Sr ,30 Dec 2016
    I had a bad problem with those bud eating caterpillars they got inside the biggest buds I have ever grown 19inch buds and when I noticed some parts of the buds didn't look right i touched it to feel it […]Read More
    1. By Roy ILGM ,30 Dec 2016
      Ouch that's harsh, sorry to hear J!
  12. By MAGGIE ,19 May 2017
    Does anyone know if the birch borer will attack marinara plants? I have a lovely birch that I suspect may be infected and it is pretty close to where I would plant my plants outside
    1. By latewood.ILGM ,25 May 2017
      Maggie, Best thing you can do is to monitor the plants and be ready with insecticidal soap or some other safe option. Happy growing :) – I❤️GM
      1. By latewood.ILGM ,25 May 2017
        Maggie, You could also be proactive by dusting the area with Food grade CODEX Diatomaceous Earth. – I❤️GM
        1. By jim byrd ,10 Sep 2018
          can I dust the plants with food grade D.E. or just the ground around the plants. cause i dont want to make a huge mistake.
  13. By Jeff Jackson ,28 Aug 2017
    Is there any guides just for pray mantas
  14. By Terrance Hirchag jr ,29 Jun 2018
    Well i picked off all the catapillars i could find on my plants then sprayed it down with the soapy water then rinsed it down then waited till this evening to spray it down with the neem oil spray. I […]Read More
    1. By latewood_ILGM ,03 Jul 2018
      I already answered this somewhere but, here goes. No. Do not rinse off the organic and dissipating neem oil. It might be OK to give the plant a tepid shower at harvest time as long as you have 4-6 fans […]Read More
  15. By Ryan ,12 Sep 2018
    Anyone using Spinosad? Sounds very promising. I talked to an extension agent in the middle west who said corn earworm were HORRIBLE this year. I got them first time ever in over 30 years of outdoor projects.
  16. By Mary J. Flores ,21 Sep 2018
    How much time should there be between spray (Safer Caterpillar Killer) and harvest? A week a couple of days?
    1. By latewood_ILGM ,26 Sep 2018
      Mary J., Read the directions. There will be a paragraph that tells you how long before harvest that you can use the spray. :)
  17. By T ,21 Sep 2018
    How often can you spray the plants with need oil soapy spray?
    1. By latewood_ILGM ,26 Sep 2018
      T, Once every week depending on the pest. Never use Neem oil in late flower or buds will taste like "poop" :)
  18. By T ,21 Sep 2018
    Please help!!!! My whole crop is infested with tiny caterpillars. We're picking them out one by one and sprayed neem soap spray. Do you also need to cut out brown spots as well? Can you still smoke or is it […]Read More
  19. By latewood_ILGM ,26 Sep 2018
    T, You would be helped in real time by joining our support forum at: There are many other options aside from Neem oil.
  20. By Ronald M ,19 Aug 2019
    Mahalo for writing this, got awesome info. Came in handy. Mahalo from da Hawaiian kingdom.
  21. By sandy wilson ,16 Sep 2019
    it is almost harvest and signs of caterpillers are appeariing in my outdoor garden. .tiny ones in the buds killing them off. huge ones...several all sizes and you have to Practically destroy the bud to find them. what can i […]Read More
  22. By Tommy ,24 Sep 2019
    What to do once your hemp is harvested and then the budwormshatch in hemp
  23. By Rox ,27 Sep 2019
    Found one caterpillar on one plant Searched for 3 hrs. To rid of anymore. Have to clean leaves of poop. Second plant has signs of poop but no sigh of caterpillar What do I do with my buds to protect?
  24. By Oscar ,18 Apr 2020
    I thought I had caterpillars as all my nodes grow and then disappear some of the leafs look like they are holding on by a thread I need help no one seems to no what’s happening
  25. By Nathan ,05 Sep 2020
    olive oil works great also as a replacement of neem oil
  26. By Sara ,14 Sep 2020
    Will 'mildew cure' help with these borers? I've read that most pests dont like garlic.
  27. By Melissa ,03 Oct 2020
    Hi Robert! My plants are only a couple of weeks away from harvest, and the caterpillars are out of control! How late can you spray before harvest? I'm trying to grow everything in the sun and organic.
  28. By Aprende a identificar las plagas en cultivo de cáñamo con estos interesantes consejos – Casanare Positivo para Hemp ,19 Feb 2021
    […] pero también pueden funcionar en interiores con cierta preparación. Otras intervenciones incluyen el uso de un producto como el spray Bug Blaster o el aceite de neem (que puedes hacer […]
  29. By David ,28 May 2021
    I had small 1 inch long caterpillars or army worms or borers, anyway, I did not see any sign of them until the tops of some colas dried out. The top simply came off and you could see a hollow […]Read More

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