Soundz of Summer

Almost everyone has a sound that they associate with summer. For some it is the call of the cicadas at dusk. For others it may be the tick-tick of the garden sprinkler. For me it is the muscular buzz of the robber fly hurtling past looking to catch its prey on the wing. Robber flies are the terminators of the insect world and though I hear them I rarely see them flying such is their speed.

Recently I heard a buzz almost as powerful. The source was easily seen and luckily landed on a nearby bush. It was a pair of mating March Flies –in this case Yellow Tangle-vein Flies (Trichophthalma sp.), I think.

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Both male and female flies feed on nectar and plant juices. However when the female fly is producing eggs it requires protein which it gets by extracting the blood from warm-blooded animals particularly livestock, domestic pets and humans. The mouth parts are equipped with two knife-like appendages with which to pierce the skin and a sponge to soak up the blood. The sponge can clearly be seen in the photo above. Although the bites may trigger allergic reactions in some people, most only feel a short pain followed by itchiness which is due to the anticoagulant the fly injects to ensure a continuous flow of blood.

This pair sat mating until the camera got too close after which they took off still connected. Because of the difference in wing strength between the two flies they flew off spinning quite rapidly. Mating in the air can be a dizzying experience (I’ve been told).