Linden Looper Caterpillar (Inchworm)

2008 January 12

S_ found this one back on June 1. It’s been a while, and she forgets the details of how she found it now[1], but she thinks it was hanging by a thread from one of the apple trees[2]. It was a bit over an inch long.


It looks like a Linden Looper, Erannis tiliaria. While the Bug Guide information page has good pictures, so far it kind of leaves us hanging for details about this caterpillar’s lifestyle. So, let’s see what we can find elsewhere:


With a name like Erannis tiliaria, and the common name “Linden Looper”, you’d think that it eats leaves from Linden trees (genus Tilia, commonly known as Basswood in the US). And you’d be right. It turns out that they aren’t too finicky, though, and will also eat leaves from elm, hickory, maple, oak, birch, and apple. Eggs hatch first thing in the spring, about the time the leaf buds start to burst. The caterpillars eat leaves until about July, then they make their way to the ground and burrow down an inch or more to pupate. The adults then emerge in the late summer or early fall, and the females lay eggs in places like bark crevices. The eggs then overwinter, and the whole thing starts over again in the spring. An interesting feature of these moths is that, while the males have wings and fly around normally, the females are wingless. She basically emerges from her pupa, waits for a male to come by and mate with her, and then crawls off to a nearby tree to lay her eggs.

These caterpillars are considered to be a type of “inchworm” or “looper”, and are called that because of the way that they walk:


(sorry about the blurry picture, but it does show the “looping” action pretty well). Unlike other caterpillars, inchworms don’t have any prolegs in the middle of the body, they just have the six true legs at the front and four prolegs in the back. They walk by grabbing hold of something with their front legs, then “looping” their body so that the rear end moves forward. They then let go with the front legs, and stretch out their bodies to grab on again:


On a good surface, they can move pretty fast, and they can reach across fairly large gaps between leaves. Sometimes they lose their grip and fall, but they lay down a silk line wherever they go. If they fall off, they dangle from the tree by the silk line until they can climb up, so it is not uncommon to see these caterpillars sort of hanging in midair with no visible means of support (which is how S_ found this one). There are a lot of species of inchworms, most of which are a lot less colorful than this one (a lot of the other inchworm species are camouflaged to resemble twigs)

[1] And, of course, I didn’t write anything down at the time, trusting to my memory. You’d think I’d know better. I just can’t remember that I can’t trust my memory, maybe there’s a connection . . .

[2] Yes, I know, *again* with the apple trees. Well, to be fair, they are the trees that are nearest the house and that we spend the most time around (it isn’t much fun hanging out under spruce and pine trees, what with the resin and the needles and all). She thinks she was mowing under the trees at the time, and ran into the caterpillar as she was driving under.

6 Responses
  1. February 28, 2008

    i don’t know where you got those pictures, but they are cool.

  2. February 29, 2008

    Thanks. I took them on the kitchen table, on a sheet of paper in natural light, with a Canon Powershot A95 camera in “macro” mode.

  3. May 27, 2009

    As it turns out, I might have some pictures of the adult form too, although its wings are so faded that it is hard to be sure.

  4. Ramsey Piotter permalink
    May 29, 2010

    I found a catipillar like this on my shirt when we were in the woods. Is it rare? What should I do with it? What does it eat? Should I let it go? Please answer my questions!!
    Ramsey Piotter
    PS Is it a catipillar or an inchworm or what??

  5. Ramsey Piotter permalink
    May 29, 2010

    What does it turn into?? A Butterfly??

  6. May 29, 2010

    They aren’t rare, no. I see them pretty often. They are one of a few thousand kinds of inchworms. The caterpillars are the interesting-looking ones, the moths are kind of a nondescript brown.

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