Backyard and Beyond

Revisiting this large crane fly. Rather prominently on the left side of the fly is a halter (also spelled haltere). The creature has two of them. This is a big fly, so they’re really quite prominent, but every fly has them (plural: halteres). They can be paddle-shaped, drumstick-shaped, even a bit bowling pin-shaped.

Here they’re visible on a Margined Calligrapher fly.

On a something or other, perhaps Sepsis black scavenger fly.

Eudioctria genus robber fly. Halteres are often hard to spot, but these pale ones stick out.

The basic insect pattern is four wings. Think bees, wasps, damsel- and dragonflies, moths and butterflies. Flies have one pair of wings, a fact hallmarked in the name of their order Diptera, which simply means two wings. The halteres are where the hindwings would be on a “standard” insect, and are, in fact, evolved from hindwings. Another order of insects has halteres: the fairly obscure Strepsiptera, the twisted-wing insects, which are mostly endoparasites of other insects. But in their case, the halteres are modified forewings.

The abilities of two pairs of wings in the air are remarkable: just watch a dragonfly. But flies aren’t bad fliers with just their two wings. Not at all. Oh, hell, that mosquito, for instance, knows where and how to go. Halteres help them fly: they are balancing organs that oscillate during flight, on-board gyroscopes.

You want an awkward flier: how about a beetle? In their case, the forewings have evolved into tough elytra, sometimes elaborately patterned or pitted, that have to open like barn doors before the hindwings can get to business. You’ll see beetles walking more than flying.