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Aphid predators
Most plants in gardens and glasshouses can be attacked at some time by aphids, which suck the sap and distort growth. Fortunately, several naturally occuring predatory insects keep their numbers down - including ladybirds, lacewings and hoverflies. Although the adults of these insects may be familiar to most gardeners, their larvae are less well known.
Ladybird larvae are up to 12mm (0.5in) long and are greyish-black with variable amounts of orange-red or white markings. Some species of ladybird larvae have spiny bodies. Many ladybirds prey on aphids but some specialise in eating scale insects, red spider mites or even powdery mildew spores.
Hoverfly larvae are legless maggots with flattened, relatively broad bodies up to 12mm (0.5in) long. They often have semi-transparent bodies so internal structures, such as the gut, can be seen. There are 265 hoverfly species in Britain and just under half have larvae that feed on aphids.
Lacewing larvae eat aphids and other small insects, which they seize with their curved jaws. They are up to 8mm long with tapered rear ends. Some lacewing larvae camouflage themselves by placing sucked-out aphid skins among the bristles on their upper surface.
Andrew Halstead