As promised, I’ll be posting some pictures of flies we caught in and around Tucson, Arizona. But before we can talk about the flies, we need to talk about the local flora. The host plants for these flies serve as a restaurant, discotheque, bedroom, and nursery. In Arizona, those plants tend to be cacti. Below the fold I have posted a picture of a cactus that met a sad fate: it was struck by a bold of lightning. But from the ashes of the dead saguaro came a diverse collection of Drosophilids.
Drosophila are NOT true fruit flies (see here), and they prefer rotting plants to fresh fruit. For this reason, they are not an agricultural pest — the plants they hang out on have already been done in by various microbes, including yeast which ferment the sugar.
Many of the flies in the Southwest United States and Mexico feed, mate, and oviposit in rotting cacti. A cactus may have a gash in which yeast have infected, fermenting the sugar found in the fleshy insides. Or a cactus could be struck down by a bolt of lightning:
When we cut open one of the fallen arms, this is what we found:
As a point of comparison, the flesh of a saguaro is usually bright green or white. This plant has rotted away from the inside, making it a haven for insects of all varieties. In the next post, I’ll show you some of the flies we caught feasting on this banquet of fermenting cactus.