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Milkweed Tussock Moth Caterpillars Feeding

milkweed tussock moth2 038Female milkweed tussock moths lay their eggs in masses on the underside of milkweed and dogbane leaves, which their larvae will eat. The hatching caterpillars are gray and hairy, but in no time they have developed the tufts of hairs that give them their name and make them resemble little mops. When still fairly young, the siblings stay together, skeletonizing the leaves they consume, leaving only the strongest veins that contain sticky latex. As they mature, the caterpillars tend to wander, and it’s unusual to find large groups of them on a single leaf. At this point they often cut through a vein in order to prevent the latex from reaching the area of the leaf where they are feeding. (Older monarch caterpillars use this same tactic.) Like monarchs, milkweed tussock moths, because they’ve consumed the cardiac glycosides contained in milkweed and dogbane leaves, are toxic to predators.

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5 responses

  1. mmwm

    Is it normal/usual/OK for so many to still be here, as caterpillars, as the first frost quickly approaches? My yard in central NH is still filled with them.

    September 15, 2014 at 2:33 pm

    • It does seem late, but most of the ones I am currently seeing are older individuals, close to pupating. (Today’s photograph was taken a couple of weeks ago.)

      September 15, 2014 at 2:58 pm

  2. Pat

    I just photographed a leaf full of these in the last few days too and posted images to Facebook. It’s fun to see how we are seeing the same things. And often I get a new bit of info from your posts, which makes it all the better!

    September 15, 2014 at 2:58 pm

    • I saw them, Pat — smart minds think (and observe) alike!

      September 15, 2014 at 3:17 pm

  3. Susan McCoy


    September 17, 2014 at 1:46 am

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