Friday, June 20, 2014

Caterpillar Season

A few days ago it was unbearably hot and humid out, but I was enjoying it nonetheless because this seemed to bring out all the ants and other bugs of interest. There were so many types of ants wondering all over my plants that I was tempted to make a video about them all but the mosquitoes got the better of me.

One thing I had to photograph was this patch of caterpillars on my Persimmon tree. My assumption was they were some type of giant silk moth but I don't believe that to be the case.

Unfortunately they were all dead the next morning. No doubt a large black carpenter ant, Camponotus pennsylvanicus, came along and chewed them all up into mush as there were several of those out on the tree. The whole clutch of them could have fit on a quarter, they were that tiny. I'm kicking myself for not removing the leaf and placing them into the butterfly cage.

I've no idea what they were, other than they were on Native Persimmon, they're were sort of hairy, and that I live in New Jersey. If anyone out there wants to take a crack at identifying them, be my guest. 

So I then realized this week, there are a lot of caterpillars in my yard! 


The Eastern Redbud has Fall Webworm, Hypantria cunea, which are poorly named because it's clearly the start of summer.

The tree also has treehoppers and a few aphids which are attracting ants that are supposed to help prevent insect herbivores or at least discourage and harass them onto other plants. It's not a perfect system but it does have an effect.

Fall Webworms get around this though by sticking together in a small group and forming webs around the leaves they eat for protection.

They do this until they're big enough to take on a few ants or develop other defenses. I'm not sure what they are for this species but I know long hairs, tasting bad, chemical weaponry, are a small taste of what some caterpillars do for protection. It's the early instars when the caterpillars have basically just hatched and don't have these defenses when they're picked off by everything, like the ones I found on the Persimmon tree.


The Eight-Spotted Forester is a day-flying moth (not quite a butterfly) that hosts on grape vines. The adult has black wings and eight cream/white or pail blue spots on the wings, hence the name.

Caterpillars are somewhat colorful looking and are in the habit of jumping ship upon disturbance, often leaving a silk lasso behind so they can climb back up. Grape Vines are very aggressive growing and often the caterpillars don't effect the yield of the crop.

Now I tried looking up what young Eight-Spotted Foresters look like, and I don't think these are them. What interests me is that the grape vine doesn't have any pores that produce extra floral nectar or attract aphids and other insects to do that for the plant. So that means the only ants walking over the plant are simply foraging for the sake of it, meaning fewer ants compared to a plant that's gushing out food to encourage them. So I'm curious to see how far these guys get.

And lastly the False Indigo Bush, Amorpha fruticosa, has not only eggs but fully grown caterpillars on it.

Silver Spotted Skippers, Epargyreus clarus, forage at night, making them hard to spot. During the day they stay inside a small "shed" of leaves they've woven together to hide from birds. Smaller caterpillars simply chew a section of a single leaf and fold it over with silk.

This is another case of the plant not attracting ants, other than letting them steal nectar from the flowers, but even this isn't a popular practice compared to other plants.

The caterpillars are a decent size and employ an additional tactic to hide from ants. One of the things ants look when hunting is insect frass; when they find it they know an insect can't be far. In this case though the caterpillars actually launch their frass pellets several feet away from them. They also lay silk down on just about everything they walk on to discourage ants from following them.

1 comment:

  1. How far did those little green caterpillars on the grape vine get? I found a couple hundred that looked exactly like those a week ago on my vine. The images I see for Eight-Spotted Forester caterpillars don't look anything like those guys, so I'd like to know if that is in fact the correct ID.

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