Insect of the Week - Syrphid Flies

Before moving on to this week's insect, let's first reveal last week's mystery insect. All the images of the insects shown in last week's post were flies. That's right, flies!

The fly shown below is a deer ked (Lipoptena depressa), which is a type of Hippobiscid fly. These flies are external parasites that feed on the blood of birds and mammals. Highly specialized claws help them cling to the hair or feathers of their particular host species. Deer keds have wings when they emerge from their puparium, but lose their wings once they find a host.

Photo: Alex Wild (www.alexanderwild.com)

Most of us have seen a house fly (Musca domestica) more times than we'd like, but I bet you haven't seen one emerging from it's puparium. That's what's happening in the photo below. Pretty cool, huh?

Photo: Alex Wild (www.alexanderwild.com)

Many species of flies use their wings for communication. The Ulidiid fly pictured below sports both pigmented spots - visible in the wing silhouetted by the flower petal - and rainbow reflections, visible in the wing against the dark background. Ulidiid flies are sometimes referred to as picture-winged flies because many of them have patterns of bands or spots on the wings. Flies have only two wings as an adult; the hindwing has been reduced to small knobs, called halteres. In the photo below, you can clearly see the haltere, which is the small knob-like structure seen behind the forewing.

Ulidiid fly (Photo: Alex Wild, www.alexanderwild.com)

Adult hover fly visiting a flower
(Photo: Alex Wild, www. alexanderwild.com)

Now on to this week's insect - the syrphid fly. The other two images seen on last week's post were both photos of syrphid flies. These flies are also commonly referred to as hover flies or flower flies. As the common name suggests, adult hover flies can often be seen hovering or "nectaring" at flowers.

Syrphid flies are a large group of medium to large flies, ranging from 1/4 to 3/4 inch long. Most adult syrphid flies are black or brown with yellow banded abdomens and body markings (see photo at left). Many have dense hair covering the body surface. At first glance, these flies often resemble bees and wasps. However, syrphid flies have only two wings, while bees and wasps have four wings. Also, flies have very short antennae that may be difficult to see; the antennae of bees and wasps is longer and more conspicuous.

A predatory syrphid fly larva feeding on an aphid
(Photo: Alex Wild, www.alexanderwild.com)

Syrphid flies are beneficial insects, especially in the garden. Adults feed on the nectar and pollen of flowers, and pollinate plants. The larvae of some species are predaceous, feeding on aphids and other soft-bodied insects (see photo at right).