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Friday, April 03, 2009

Coprosma Leaf with Tachinid: an Appreciation

Some people say these bright shiny coprosma plants are nice--pretty--interesting--but too hard to blend into a garden because the bright shininess doesn't readily harmonize with other plant textures. I think it goes well with succulents, under the lemon verbena tree which has lime green leaves about the same color, with sunset-colored arctotis flowers, and even with dusty miller (Senecio cineraria) in a high-contract kind of way. The plant provides brilliant color without relying on flowers, and has remained cheerfully yellow-ish through the winter.

The fly resting on the shiny leaf is a tachinid. Tachinids are hairy and coarse looking, and may resemble house or blow flies superficially, but their habits are different. Most tachinid larvae (that is, maggots) are parasitoids on a wide range of other insects. The adult flies feed on pollen, nectar, or honeydew from plant-sucking insects. The guys at Natural History of Orange County (Peter J. Bryant and Ron Hemberger) have done a great job of expanding the number of species pictured and identified there, especially among the flies. It is very helpful to have such a resource of locally occuring species for indentification purposes. Based on their information I would tentatively place this tachinid among genus Archytas. Why is indentification important? Once you know the type of insect you're dealing with you might be able to find out how it breeds, what it feeds on in each of its life stages, whether it is beneficial to your enterprise, how to control its spread if necessary, etc; or you might be able to actually contribute to the body of information on the species. Knowledge is power. Thanks, NHOC for your work documenting Orange County insect and spider species!

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