Diptera are fascinating insects – diverse, bizarre, economically and medically important – but underappreciated by most people other than dipterists. We launched this series in an earlier post with a selection of five randomly selected reasons flies are great. In this installment, we bring the total up to a nice round ten reasons (but the master list currently stands at 35 reasons and counting, so there will be more posts to come).
Without further adieu, we present reasons 6 – 10:
6. Bee riders. Braula is one of the most non-fly-like flies on the planet. Adults look more like spiders or mites than flies. Their natural history is almost as bizarre as their appearance. Braula larvae spend their lives inside honey bee hives, where they tunnel in wax cells and feed on pollen and other materials in the cells. The adults force their way out of the cells and attach themselves to an adult bee with specialized claws, clinging to the bee like a tiny rider on an enormous horse, and feeding on liquids from the bee’s mouthparts.
7. Spider hunters. In the age-old interaction between spiders and flies, spiders usually win, but not always. Pseudogaurax is a genus of chloropid flies that specializes in turning the tables on spiders. An adult female Pseudogaurax lays eggs in or on the silk-wrapped egg case of a spider and the newly-hatched fly larvae crawl into the mass and start eating the spider eggs until the case contains nothing but flies. They sometimes pupate inside the egg mass, concealed from predators, and emerge through the silk wall as adult flies.
8. Strange flowers. The standard public perception of a flower is that they are pretty, and smell nice. This is not always true – some flowers stink. They smell like rotten meat, or dead animals, or dirty laundry. “Who would pollinate such a thing?” we may ask. “Flies” is usually the answer. The southeast Asian flower Rafflesia is often considered the world’s largest flower. It looks, and smells, like rotting meat. And it is pollinated by carrion-feeding flesh flies. In Central America, on a walk through the forest you will sometimes be convinced that you are approaching a very dead large animal. Instead you turn the corner and discover the source of the smell – the bizarre, beautiful flower of Aristolochia. Like Rafflesia, these flowers are pollinated by flies, but they go a step further and have an elaborate trap built in that imprisons the flies, who wander around inside the flower, becoming covered with pollen until the flower begins to wilt and the flies are released, carrying pollen that will then be delivered to the next Aristolochia they visit. Without these “filthy” carrion-feeding flies, many of these wonderful flowers might have a very bleak future.
9. Polar explorers. The farther north one goes the more dominant flies become. In the high arctic, familiar groups like grasshoppers, true bugs, most beetles and ants are minor players, or even completely absent. They simply do not seem adapted to life in a place where summer lasts only a few cool windy weeks and the ground is permanently frozen. Flies, on the other hand, seem to easily take over the roles abandoned by these “lesser” orders, becoming the dominant insects in just about every trophic group in the arctic. In the north, every food web on land or in freshwater runs through Diptera.
10. Stalk-eyes and antlers. In battles between males for potential mates, most people imagine deer or sheep smashing horns or antlers together, or overgrown seals fighting for dominance of the beach. Some entomologically-inclined individuals think immediately of enormous scarab beetles using their horns to push or throw each other off logs. Few people get low enough to the ground to notice the flies engaged in epic battles of their own. Several species in many families (Diopsidae, Drosophilidae, Clusiidae, Tephritidae, Richardiidae and more) have a bizarre assortment of elongated eye-stalks (or even elongated eyes), antlers, horns, or cheek projections that are used in male-male combat over control of prime mating sites. These tiny dances on a dead log are every bit as exciting as bighorn sheep on a mountain ridgetop.
Next time: five more reasons, including the CSI effect, bird feeders, and glow little glowworm . . .