August 2nd, 2010


Urban Nature Pictures 7/19; 50 more urban species #21 Tiger Bee Fly

Tiger bee fly, Xenox tigrinus

This large fly is usually met with some alarm, at least until its identity is known. I was among those who noticed its close resemblance to the notorious biting horse fly and deer fly group. As it turns out, this fly is friend, not foe. It lays its eggs in the burrows of the destructive (from a homeowner's point of view) carpenter bee, and the developing maggot feeds on the bee's larva.

On a side note, I like the fact that this animal's common name is three animal names in a row. "Tiger" modifies "bee fly," in this instance--other bee flies (Family Bombyliidae) are fuzzy and resemble bees.

50 More Urban Species #22: American carrion beetle

American carrion beetle Necrophila americana

This is an animal that I associate with my old job at Drumlin Farm. During the summer we would clean the golden eagle cage, and find the remnants of a big white rat that the eagle had eaten only partially. The carcass usually had several of these beetles on it. It was a strangely nostalgic experience to find an American carrion beetle at Franklin Park--this time on a dead white footed mouse.

The American carrion beetle is not to be confused with the American burying beetle, which is likewise found on carrion, but is in fact an endangered species. The carrion beetle is not endangered, but may be on the decline, due to the fragmentation of the forests of eastern North America. The carrion beetle visits carcasses shortly after carrion flies do. The beetles feed on the maggots, as well as the mushy dead flesh of the carcass itself. Their own larvae feed on the carcass and its inhabitants, and the wikipedia entry on the species hints that the beetle's efforts comprise a rudimentary kind of parental care. (In burying beetles, the care is less vague, with the adult beetles hiding the carcass under a layer of soil, staying with it as the larvae develop, and regurgitating food for them.) I expect that the entomologists reading this may clarify the issue--particularly those forensic entomologists I prevail upon so often.

The American carrion beetle is fairly distinct, with yellow and black markings on the pronotum. The abdomen protrudes past the wing covers, as it does also in burying beetles, and the related rove beetles.