A taste of honey

Aphids might be the bane of gardeners' lives, but they act as pastry chefs to yellow meadow ants and are the favoured snack of both ladybirds and lacewings, finds Ian Morton

ONE is a compact beetle with a hard, brightly coloured dome marked by black spots, the other is a flimsy phantom with a translucent lime-green body, orange compound eyes and four oversized diaphanous wings fit to carry a fairy skyward. The tenacious ladybird and the ephemeral lacewing have nothing in common by way of appearance, but both hibernate and both produce overwintering eggs, which hatch into horror-film larvae with a voracious appetite for the same prey. The larval stage of the rotund ladybird deservedly gets widespread credit for chomping 200 aphids a day and the adult culls a further 50 or so. The larva of the fragile lacewing, emerging from individual eggs suspended on fine hairs attached to the food plant, is equally active against the garden pest, but has never attracted the same recognition or respect. Its method of feeding is also different. No grabbing and munching for this little predator: it pierces its prey with a hollow head-mounted maxilla (or needle), injects a fluid that dissolves the aphid's innards, then sucks the soup back through the needlea process that takes a mere 90 seconds. It gets through some 100 aphids a day and the adult lacewing mops up more, using its mandibles. Little wonder that, among entomologists, the lacewing has two graphic nicknames, aphid lion and aphid wolf, whereas the ladybird enjoys a genteel identity linked to the red of the Virgin Mary's cloak in medieval paintings.

The lacewing can also claim a particular distinguishing feature-it can hear. Tympanal organs at the base of the radial vein in each forewing, the smallest known in Nature, can detect the ultrasonic signals emitted by bats, so the lacewing aloft in the evening closes its wings and drops to safety. In addition, scolopidial organs on the insect's legs pick up low-frequency sounds produced during courtship, inviting contact with a partner. By contrast, in typical beetle fashion, the ladybird is deaf.