148 
INSECTS. 
the middle line, and the claws of the tarsi accompanied each by a slender hook, so 
that they appear double. Many of the species possess vesicating or blistering 
properties, and the family is for this reason sometimes known as the Vesicantia. 
The larvae are interesting on account of their habits and the changes of form 
they undergo in the course of their development. These changes are well illus¬ 
trated in the case of the oil-beetles ( Melde ). The larvae of these when first 
hatched from the egg are active little creatures furnished with six legs. They 
climb on to flowers, and wait in readiness to fasten themselves to the hairs of bees 
coming to gather the honey. In this way they get carried to the nest, where they 
devour the eggs of the bee. They now cast their skin, appear as little, maggot-like 
OIL-BEETLES AND LARV.E (nat size). 
grubs, with much reduced legs, and feed on the honey intended by the bee for its 
own young. After a time they change to the form of a pupa, from which, instead 
of the perfect insect, a third form of larva, somewhat similar to the second, 
emerges, while a further change is still required before the true pupal stage is 
reached. Seven species of Melde occur in Great Britain, but, with the exception 
of one or two, are very rare. When handled or irritated they exude an oily- 
looking liquid of a yellow colour from certain of their joints. This secretion, 
to which they owe their name of oil-beetles, has a burning, acrid taste. 
The Stylopidce are remarkable little insects, which live parasitically in the 
bodies of wasps, bees, and bugs, and present a type of structure distinct from 
that of all other beetles. The male is a 
winged insect, with coarsely - faceted 
prominent eyes, large fan-shaped wings, 
and extremely small inconspicuous elytra; 
the first two thoracic rings are very 
short, while the metathorax is greatly 
elongated and covers over the base of the 
abdomen; the hind-legs are placed a long 
way behind the middle pair, and the tarsi 
1, Xenospeckii— male; 2, female. (Both enlarged.) of all the legs are membranous under- 
