• 32 Comments

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 breakdown.

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

Signs of caterpillars

Signs caterpillars cannabis

All it takes is about five to ten caterpillars to demolish your plant. What’s even worse is that the hole Corn Borers carve into the stems creates an open doorway for other pests that will complete suck the life out of your marijuana plants. Hemp Borers will damage the buds (see picture).

You can easily identity their damage by the chew marks left on the leaves.

Download my free marijuana grow guide at this link for more growing tips

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. Observe the plants stems to see if there are holes with brown trails around them. If you notice visible holes on your plant, then you most likely have a problem.

Not sure if caterpillars are causing the damage to your marijuana plants? Check the article Marijuana pest and bug control for a list with pictures of all pests and bugs

How to get rid of caterpillars

Get rid caterpillars weed

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.

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.

Download my free marijuana grow guide at this link for more growing tips

A commercial product like Bug Blaster will always to the job. If you want to be sure to kill them all buy something like Bug Blaster.

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

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.

Remember that plants with strong genetics have less change of getting sick and are less vulnerable for pests and diseases. So make sure you buy your weed seeds from a trusted seed bank.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible

Robert

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
  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: support.ilovegrowingmarijuana.com 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

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