On this page, Overview - mimicry - food and behaviour - hover fly eggs - hoverfly larvae - related pages
There are 6,000 species of hoverfly world wide, and 281 species in the U. K. Adult body length ranges from 0.4 mm - 2.8 mm worldwide. The adults are often brightly coloured attractive flies. Note the the aristate antennae (see photographs below) and huge eyes typical of the more "advanced" flies. In most U. K. species the eyes of the males meet at the top of the head, but are separated in the females. It is usually the in adult stage that we most commonly see hoverflies, but this stage may last only a few days, or at most a few weeks. The main function of the adult is to mate, and for the female to lay eggs.
Below is the wing of a typical hoverfly. Note that many of the veins do not reach the edge of the wing.
Hoverfly larvae are maggot-like without legs. Predatory larva are blind and rely on chemical clues and touch to locate their prey. Once the prey item has been located the larva pierces the skin with its mouth hooks and sucks out the contents of the prey body. A fully grown or almost grown larva can eat an aphid in less than two minutes.
Above is an aphid-eating hoverfly larva. It has stuck the skins of sucked-dry aphids to its body - they are the little white things on the centre of its body. A larva like this can eat 50 aphids a day.
The pupal stage can last for just a few weeks to several months, depending on the species. Pupation sites are usually near the larval habitat, or in species that overwinter as pupae, they tend to be well hidden. When the larva pupates the pupa is brown and stuck to the plant or some other surface, see the photograph below.
There are also aquatic larva, like the rat-tailed maggot below, they tend to pupate near the water.
The eggs are usually white. Eggs that hatch into carnivorous larvae are usually glued singly to plants amongst or near their prey. Eggs of non-carnivorous species are usually laid in batches on or near the larval food.
Many hoverflies 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. See page 2 for photographs.
Many Hover fly larvae are slug-like and eat aphids (see above), others are scavengers.
Adult hover flies feed on pollen and nectar, so are valuable pollinators. The female hoverflies (in common with many other female insects) need the protein in pollen for egg production. They prefer open flowers where the nectar and pollen are easy to reach, such as umbellifers, especially with white or light coloured flowers, so daisies, hogweed and thistles are popular. Most hoverflies do not have specialised mouthparts, as they are not needed to feed from these types of flower.
Flight speed has been recorded as 3.5 metres per second with a wing beat of 120 per second. Compare this with other insects.
The photograph on the below shows mate seeking behaviour. The male hoverfly generally has two strategies in seeking a mate. Mating usually lasts just a few minutes.
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.
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