100 More Species #27: Ommatius Robber fly

Robber fly, family Asilidae
EDITED TO ADD: Ommatius sp.

Robber flies are predatory flies often seen feeding on other flies. Some robust species are adapted for hunting bees, and some are themselves bee mimics. Most of the time people encounter them perched, as the individual pictured here is. The posture is distinctive, and reveals their long legs, which are used to catch prey in mid flight. Once the prey is captured the robber fly feeds in a matter similar to a spider: it injects a paralyzing neurotoxin and digestive enzymes, then drinks the insect dry. Robber flies will perch on humans harmlessly, but if you try to catch one in your hand it may bite you. These photos have been at Bugguide for over a week, but no robber fly specialist has made a more specific identification. There are over a thousand species of robber flies in North America.

EDITED TO ADD: My pic on bugguide was moved to genus Ommatius on 6/17/2013.

100 More Species #28: Silver-spotted skipper

Silver-spotted skipper Epargyreus clarus

The silver-spotted skipper is one of the largest most conspicuously-marked of this family of small fast-moving butterflies. The body can be a much darker chocolate brown (in fact, the illustration in the Audubon Guide to New England is so dark that the animal is hard to recognize) but the silver spot on the wing is consistent--irregular, but consistently so. The larva of this butterfly is nocturnal and feeds on leguminous plants that are easy to come by in the city and suburbs, like locust trees, and groundnut, and wisteria. I learn from the caterpillar guide we use, that the larva is anatomically adapted to expel a fecal pellet up to 38 body-lengths away from itself. THAT'S going in the podcast.

3:00 snapshot #1017

4th of July cookout at friends house in Jamaica Plain!


The traditional American dish of steak and tofu with avocado sauce, mushrooms, and fruit salad.

Five years ago today:


My dear friend rockbalancer at Drumlin Farm is happy to take over ownership of my cockroaches as I depart to work at the zoo. These days she blogs about urban nature in Los Angeles!