Sycamore Specialties, Part 1

Right across the road from those mud-covered eggs in Kentucky, there were some tiny poop-covered eggs waiting to be discovered.  I might have just passed them off as droppings if I hadn’t seen the associated larvae that had hatched from some of them.  They were the eggs of Neochlamisus platani, the sycamore leaf beetle.  This species is one of the case-bearing leaf beetles (Chrysomelidae: Cryptocephalinae), whose larvae begin life carrying around the shell of excrement that covers the eggs they hatch from, adding their own excrement as they grow.  This particular species feeds on sycamore (Platanus occidentalis), and its larval case is distinctive because it is covered with the trichomes (hairs) from the underside of its host tree’s leaves.

Excrement-covered egg of a sycamore leaf beetle (Neochlamisus platani; ~1.3 mm). The strand of silk is probably the dragline of a spider that walked over the egg.

On this empty egg case, the short silken stalk that attaches it to the leaf is plainly visible. I presume an ant or some other predator ate the egg, since the beetle larva should have walked away with the egg case.

A young larva in its case. I believe the uniformly dark band at the rim is the larva's excrement, which it has added onto the egg case from which it hatched.

An older larva, which has begun covering its case with sycamore trichomes.

In For Love of Insects (and in this paper), Thomas Eisner writes about a green lacewing larva (Chrysopidae: Ceraeochrysa lineaticornis) in Arizona that similarly covers itself with sycamore trichomes.  He suggests that the trichomes are a plant defense–impeding movement and feeding of herbivorous insects, as well as slowing evaporative water loss from the leaves–that the larva is appropriating for its own defense, as well as for camouflage.  Clearly, the leaf beetle larvae are doing the same thing.  There is at least one other kind of larva that protects itself with sycamore trichomes, but I’ll save that for Part 2.

An adult Neochlamisus also looks a lot like poop. This one is not N. platani but the very similar N. bebbianae, which I found in Ohio the day before I took the above photos. These and other beetles in the tribe Chlamisini are known as the "warty leaf beetles."

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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4 Responses to Sycamore Specialties, Part 1

  1. Pingback: Sycamore Specialties, Part 2 | BugTracks

  2. Thank you so much. I turned over a sycamore leaf yesterday and discovered a whole new world, but I didn’t know what in the world I was looking at…you helped me understand. This is a fabulous coverage! Here’s a link to what I was viewing; this is a video of ants crawling over the case of a warty leaf beetle larva on a sycamore leaf.

  3. Pingback: Monthly Mystery #24: Magnolia Fuzz Harvester | BugTracks

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