Currently viewing the category: "moth caterpillars"

It has been raining for days and the leaves toward the bottom of my tomato plants are starting to look yellow. Then I saw what I thought were tiny little white bugs and figured I could just pluck them off. Much to my surprise they were part of, or attached to, a very large slug like creature that had suction cupped itself to the plant. What the heck is it, or are they? What can I do to get rid of it? I also found a smaller orange like slug that I smushed. Again, what is it and what do I do about it? And then, because things come in threes, I found droppings, on the leaves, that were the size of a small childs fingernail bed. hard to tell if it is bird poop or otherwise. This is the first time I am growing vegetables and these plants were hand cultivated by good friends. I want to make sure I do the right thing…too embarrassing to let their hard work, and mine, go to the bugs.
Please help.
Many thanks!
Risa Hochroth

Dear Risa,
I wish you had sent a photo. The tiny white bugs you found were doing your job for you. It is perfect bio-warfare. They are the pupae of a type of parasitic Braconid wasp. The female wasp lays her eggs inside (using an ovipositor) the larva of a tomato hornworm, a common pest on tomatoes. It is the green sluglike creature you found. The larvae of the wasp eat the hornworm inside out, then pupate on the outside, the stage you discovered. The caterpillar then dies and the wasps mature and begin a new cycle. The Tomato Hornworm >is the caterpillar of a large moth, Manduca sexta or Manduca quinquemaculata. The larvae are identified by the horn at the posterior end and they attain a length of four or more inches and a girth equal to a human finger before burying into the ground to pupate. While in the caterpillar form, they can defoliate entire branches of a tomato plant as well as nibbling on the still green tomatoes.

Thank you.
So, if I have handpicked the two I saw, what should I do to prevent others from appearing and destroying the plant. I assume if there were 2 there are more, yes? I sprayed insecticidal soap on the foliage, but I am wondering if there is more I should do other than just keep looking for them and handpicking them off. On the web I read that I should not have killed the hornworm with the wasps, which is consistent with what you have said, but should I have left it there to have the wasps potentially kill other worms. I thought leaving them would just give them more time to eat the foliage and the tomatoes that they have already munched on. Also, once I harvest the last tomatoes, isthere anything I need to do to the soil to make sure that they are not going to be there next year?
Risa Hochroth

Hand picking is, in our opinion, the best means of control. Watch for the telltale signs, nibbled leaves and droppings, then search for the grazer. You can sift through the soil to locate the large pupae, but adults can just fly in and lay eggs. A dilligent eye is the best form of control since we do not endorse undue use of pesticides in the garden, especially on produce meant for human consumption.

I have grown tomatoes for many, many years and this is a first for me. I have enclosed a picture. Can you identify the larva/pupa? that is building the cocoon on my tomato? Good bug – bad bug? Thanks so much for your help.
Pat in Ida

Dear Pat,
That is one beautiful tomato. The caterpillar might be an Omnivorous Looper, Sabulodes aegrotata which matures into a medium sized rather pretty moth, however they are still garden pests. They defoliate my mint plants every year and also eat the leaves from my roses. As their name implies, they eat most any plant. They are very abundant in city gardens. During the day, the caterpillar hides in a loose webby shelter that they spin in a leaf fold, or between leaves, or in your case, on a ripe tomato. They will probably not chew the tomatoes, just the leaves.

Hi. Digging in the dirt where I usually plant my tomato plant, I discovered a cocoon the size of my thumb. It is brown and like I said, it is the size of my thumb. Any ideas what it may be? I put it in a jar with some of the dirt from where I was digging. I hope it will live. I can send a picture If will help you identify it.

Dear Michelle,
Did it have what looks like the handle on a jug? If so, it is the pupa of a Tobacco Hornworm Moth (Manduca sexta) which in its larval, caterpillar form is the dreaded Tomato Hornworm, a four inch long behemoth that devours the leaves of tomato plants, sometimes leaving them defoliated. The larva eventually buries itself in the dirt to pupate without spinning a cocoon, leaving its bare pupa to mature. The handle of the jug is actually the place where the long proboscus, a tubelike mouth that the moth uses to gather nectar from deep throated flowers. We would love a photo.

Hi Daniel. Thanks for getting back to me. I have attached a photo, but I’m afraid it’s not a very good one. It sounds like your know your bugs. My next question is, how do I get this thing to hatch? Is the moth beautiful? I would imagine that it is. I currently have it in some soil in a jar without a lid. Should I keep it out side or in the house? Let me know.


Dear Michelle,
The moth is large and mottled grey with very elongated wings. There are a series of yellow spots along the body. They are very strong fliers. While not traditionally beautiful, they are truly awesome. They are very similar to the moth used in the “Silence of the Lambs” advertisements, and you can also see a swarm of them crawling on Patsi Kensit (spelling?) in the totally awesome movie” Angels and Insects”. You are doing the right thing as far as getting the pupa to metamorphose. Do not let the soil either dry out or get too wet. Keep it out of the direct sunlight.

Thanks again for your time and the information. I hope I get to see him. I think I forgot to ask if you know how long it could take? Do you know?

Dear Michelle,
Normally they overwinter as pupa and then metamorphose in the spring. I’m guessing your specimen has passed the necessary time underground and it should be happening soon.
Good luck.

Caterpillars Second submission, once again from Hickory, NC. These caterpillars were all over town a week ago, but now they seem to either died or cocooned. Please identify and provide some background. Thanks!
Gene Annas

Hi Gene,
The website Caterpillars of Eastern Forests has a photo which identifies your caterpillar as an Orange-striped Oakworm (Anisota senatoria). The site says it is: “Charcoal black with orange-yellow stripes that fade appreciably in prepupal individuals. Head black. Second thoracic segment with long, black spinulose horns. Abdominal spines relatively small. Gregarious in early instars, then solitary. Occasionally reaches outbreak densities. One related species occurs in southern Ontario, and another in Florida and Georgia. Food: oaks and chestnuts. Caterpillar: August to October; 1 generation.” The adult moth is a pretty orange color.