26 May 2009

That's One Big Silk Moth!

While I was in East Lansing, Michigan on Sunday for the annual Michigan Botanical Club Spring Foray, Lindsay was at home adding to our yard list. As she was riding her bike down the driveway, she saw this dead moth.
This is a Cecropia Moth (Hyalophora cecropia), also known as a Robin Moth. This species is a member of the Giant Silkworm Moth subfamily of the Wild Silk Moth family. Adults of this species typically only live for 2 weeks. One of the largest species of moth in North America, Cecropia Moths can have a wingspan of up to 6 inches. They can be found throughout much of eastern North America, and in scattered locations throughout the western United States as well. These giants are nocturnal and are most often found in or near hardwood forests. Cecropia Moth caterpillars feed most frequently on apple, ash, box elder, cherry, lilac, poplar, sassafras, and willow, but can also be found feeding on birch, elm, larch, and maple.
Unfortunately, Cecropia Moth populations are apparently in decline as a result of introduction of a predatory non-native tachinid fly introduced to control gypsy moths (Lymantria dispar). Like the introduction of the Asian Lady Beetle (Harmonia axyridis) to control crop pests, this is another example of the best of intentions turning into ecological disaster.
As is the case for other members of the Giant Silkworm Moth family, male Cecropia Moths are drawn to females when the females emit pheromones, a period referred to as "calling time." Studies have shown that males can find females that are several miles away as a result of their sensitivity to these pheromones. "Calling time" for Cecropia Moths is from 3:00 AM until sunrise. It is said that males use their enormous, plumose antennae to sense the pheromones given off by females.

Butterflies and Moths of Missouri by J. Richard and Joan E. Heitzman
Caterpillars of Eastern North America by David L. Wagner
Field Guide to Insects and Spiders of North America by Arthur V. Evans

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