Hover flies, Syrphidae

Right, and below are hover flies (family Syrphidae).

There are 6 000 species world wide, and over 236 species in the U. K. Note the the aristate antennae and huge eyes typical of the more "advanced" flies. Adult hover flies feed on pollen and nectar. Many mimic the colouration and/or hairiness of social bees and wasps. This enables them to avoid attack by predators who believe they might be able to sting. This form of mimicry is termed Batesian mimicry. Many Hover fly larvae are slug-like and eat aphids (see below left), others are scavengers. Flight speed has been recorded as 3.5 metres per second with a wing beat of 120 per second. Compare this with other insects. Hoverflies are valuable pollinators.

Below left is mate seeking behaviour. The male hoverfly generally has two strategies in seeking a mate. 1) He patrols around oviposition sites. The female will have already mated if she is seeking a site to lay eggs. But if the male can persuade her to mate again his sperm will have precedence. 2) He patrols over flowers. This is shown below. He will investigate anything that

The African water lily on its first day of blooming has hundreds of showy stamens and a nice bright flower. This attracts hover flies. On day 1 in the centre of the flower is a pool of poisonous liquid that looks like nectar. When the hover fly lands on the stamen it falls into this liquid as the stamen are very smooth and overhangs the pool. The hover fly cannot climb out as there is nothing to get a grip on. So the hover fly dies in the poisonous liquid. At night the flower closes and the liquid washes pollen from day two water lilies off the body of the dead hover fly. This pollen fertilises eggs at the bottom of the liquid. On day two it is quite safe for hover flies to visit the lily as the stamens no longer hang over a poisonous pool as the pool has gone. The hover flies will gather pollen on their bodies, but will pay with their lives if they then try to do the same to a day one flower.

On the left is Piophila casei, the cheese fly, cheese skipper, in the Piophilidae family. The larva are called cheese skippers or hoppers. They get this name because when disturbed they can flex their bodies to cause them to jump as much as 15 cm. They do this by using their mouth hooks to latch on to their rear end, then flexing their body and letting go. They will also feed on ham and bacon.