Cattail Seed-Head Caterpillar

2015 July 11

Since December is one of the leanest months for finding insects to post, we decided to make a special effort to find this one on December 21, 2014. There are cattails growing in the swamp north of the house, and some of the seed-heads hang onto their “fluff” as an untidy mass through the winter. This retention of their fluff is because the seed-head is infested with these caterpillars, who bind the whole thing together with silk:

This is almost certainly Limnaecia phragmitella, it appears that they are the only known caterpillars that infest cattail seed-heads this way.

The caterpillars overwinter in the seed head, which probably insulates them from the worst of the cold weather, although they also have pretty good freeze-proofing themselves. The seed head also protects them from predators, as anything that goes rooting through looking for the caterpillars is going to mostly get a huge mouthful of fluff.

I’m told you can find these caterpillars all through the winter, and they don’t pupate until spring.

When they emerge as adults, their common name is the “Shy Cosmet”. They are little silvery tan moths with four spots on the wings. I don’t think I’ve seen any come to our porch light yet, but probably will at some point.

One Response
  1. Carole permalink
    July 11, 2015

    With the heavy rains we’ve been having the last few years we’ve had a lot of storm water run-off into our river with lots of nutrients which has caused the cattails to take off in our river. Send some of those cattail cats our way.

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