Thursday, 24 December 2009

Love Bugs

"Tis the Season..." and so on. At this time the world seems in a precarious state. What with Climate Change and the economies of many countries on the brink, it is somewhat reassuring to observe that life goes on at some levels as it always has. "Love Bugs" are so-called for obvious reasons. These are unassuming little flies in the family Bibionidae. I recall them with pleasant distant memories as a boy in San Francisco when a large species emerged each spring, in March, hence the common name in North America "March Flies". This fly was a "relict" of the sand dune fauna that once existed along the coast in San Francisco. This wonderful habitat is mostly gone now and I suspect one would have to look diligently to find one of these flies today. In the 1940's before the SF sand dunes were eliminated for homes, these flies were known to most residents as they were found on windows and plants in the gardens for a brief period in spring.

We have a dominant species in the northern tropics, Plecia amplipennis Skuse. This species is found on the light sheet most nights and can be seen resting, or mating on vegetation during the day. These flies feed on pollen and nectar and are commonly seen on native and exotic flowers. Their larvae live in the soil where they are part of the "decomposing community". Judging by the numbers of adults, the larvae must be very common in the soil and, as such, are probably important in returning leaves and other biological material back into the soil for use of other members of the community.
Males like the one above have more rounded heads and may not have functional mouthparts. They may not feed at all. Females, like the one on the right in the first photo have elongate mouthparts that enable them to reach deep into flowers for nectar and pollen.

This species exhibits a mimicry pattern that is not uncommon in tropical insects--a reddish orange fore part and a dark or black remaining part of the body. Some species are highly toxic to potential predators such as lizards or birds. This fly may also be unpalatable since it is often left alone by birds that visit the light sheet for their breakfast.

The reference below indicates there is room for taxonomic work in the Bibionidae.

Hardy, D. E. 1982. The Bibionidae (Diptera) of Australia. Invertebrate Taxonomy, 30: 805-855.


Denis Wilson said...

Hi Dave
My brother uses a slightly less polite term for bugs which fly around "joined at the hip" as the old expression is.
Nice post about a fly which I am not familiar with.
Interesting detail about the head shape of the males and females.
Happy New Year and lots of bugs to study on your light sheet.

Camera Trap Codger said...

I don't remember those flies in SF, but back when the sand dunes were being replaced with lawns, I do recall you making a fuss about Australian sod flies. Good post, mann. Keep them coming.

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