|Sawfly larvae - Bob Barker*|
In the Butterfly House at Close Gardens, volunteers bring in a number of butterflies to mate, lay eggs and hatch caterpillars to feed on native host plants and complete their life cycle in the relative security of a nursery. Occasionally a collection of foreign creatures appear, munching on the free food that has been raised for the more charismatic Lepidoptera. They were not the desired species but still are an opportunity to learn about nature. An example was this message to Kevin Firth.
"We just got a call from one of the docents...there are black caterpillars all over the willow tree and no one seems to know what they are. Can you please write what they are into the log book? I do know there are tons of webworm moth cats in the house just running around."Kevin's first response was identifying them as willow sawfly (Nematus ventralis) larvae. "They will not do any harm (except to the willow), and they give us an opportunity to show people how to distinguish between Lepidopteran larvae (caterpillars) and other similar larvae. The key is the number of pairs of prolegs--Lep larvae will have four or fewer pairs, sawflies will have five or more pairs. The sawflies are stingless wasps and are so named for a saw-like organ that the females use to cut into the foliage/twigs of the host plant to lay their eggs."
|Adult Willow Sawfly - Terry Gray|