Hover-flies
These flies belong to the family Syrphidae, within the large order of
insects called Diptera, and most are easily recognised by their
generally bright colours and hovering ability. The adult flies spend
much of their life on flowers, feeding on pollen and nectar, and thus
play an important role in the pollination of many wild and cultivated
plants. However, the adult flies are perhaps best known for their mimicry
of various wasps and bees. Although quite harmless, they no doubt get some
protection from would be predators, like birds, by copying the bold yellow
and black warning colours of their genuine stinging models. An obvious
question for most people is how to distinguish between a hover-fly and a
wasp or bee? This can prove difficult without some knowledge of insect
behaviour and morphology, but perhaps the most obvious difference (if you
can get close enough!) is that hover-flies, like all Diptera, have only
one pair of wings, whereas wasps and bees have two pairs. Aphid-eating
hover-fly larvae are rather flattened, legless and maggot-like.
Most are greenish or brownish in colour and well camouflaged, and largely
go unnoticed as they crawl over foliage in search of their aphid prey.
Lacewings
Lacewings belong to an order of insects called Neuroptera. The most
familiar members of the group are the green lacewings (family
Chrysopidae), which often find their way into houses after dark,
attracted by room-lights. A typical example of one of these insects is
pictured above. The other members of the group are the so called brown
lacewings (family Hemerobiidae). These insects are smaller than their
green cousins, and the adults have brown or greyish bodies and brownish,
often spotted wings. The adults of some lacewings frequently come indoors
or seek shelter in outhouses and garden sheds during the autumn, for
winter hibernation. All lacewings, both as adults and larvae, prey on
aphids and other soft-bodied insects. Lacewing larvae are rather
similar in shape to those of ladybirds
and, like the latter, have three pairs of well-developed legs. However,
most are coloured a sombre brown, mottled with darker spots and markings.
The larvae of some species augment this camouflage-colouring by also
covering themselves with the dried remains of their prey, so that each
one looks like a small mass of debris rather than a living insect.
Lacewing larvae have unusual sucking mouthparts, with a pair of extremely
long, slender and conspicuous mandibles (or jaws) that curve forward from
the front of the head. The mandibles are tubular structures, rather like a
pair of hypodermic needles, which are sunk into the victim's body and then
used in the manner of 'drinking straws' to suck out the body fluids of the
prey. |