FAM. 75. CANTHARIDAE OR MELOIDAE (_Blister-beetles_, _Oil-beetles_).-_-Head with an abrupt neck; elytra and sides of the abdomen without any coadaptation; each claw of the feet with a long appendage closely applied beneath it._ This distinct family consists of Heteromera with soft integument, and is remarkable for the fact that many of its members contain a substance that when extracted {270}and applied to the human skin, possesses the power of raising blisters. The life-history is highly remarkable, the most complex forms of hyper-metamorphosis being exhibited. The species now known amount to about 1500; there can be no difficulty in recognising a member of the family by the above characters, except that in a very few cases each claw bears a projecting tooth, instead of an elongate appendage parallel with itself. The penultimate tarsal joint scarcely ever broader than the preceding; the colour and style of markings are extremely varied. There are two very distinct sub-families, Cantharides and Meloides; the former are winged Insects, and are frequently found on flowers or foliage. The Meloides are wingless, and consequently terrestrial; they have a very short metasternum, so that the middle coxae touch the hind; and they also have very peculiar wing-cases, one of the two overlapping the other at the base; in a few Meloids the wing-cases are merely rudiments. The post-embryonic development of these Insects is amongst the most remarkable of modern entomological discoveries. The first steps were made by Newport in 1851,[140] and the subject has since been greatly advanced by Fabre, Riley, and others. As an example of these peculiar histories, we may cite Riley's account[141] of _Epicauta vittata_ (Fig. 140), a blister-beetle living at the expense of North American locusts of the genus _Caloptenus_. The locust lays its eggs underground, in masses surrounded by an irregular capsule, and the _Epicauta_ deposits its eggs in spots frequented by the locust, but not in special proximity to the eggs thereof. In a few days the eggs of the blister-beetle hatch, giving rise to little larvae of the kind called triungulin (Fig. 140, A), because each leg is terminated by three tarsal spines or claws. In warm, sunny weather these triungulins become very active; they run about on the surface of the ground exploring all its cracks, penetrating various spots and burrowing, till an egg-pod of the locust is met with; into this the triungulin at once eats its way, and commences to devour an egg. Should two or more triungulins enter the same egg-pod, battles occur till only one is left. {271}[Illustration: FIG. 140.—Hypermetamorphosis of _Epicauta vittata_. North America. (After Riley.) A, Young larva or triungulin; B, Caraboid instar or second larva; C, coarctate larva, or instar between the Scarabaeoid and Scolytoid larva; D, Scarabaeoid larva, from which the Scolytoid, or sixth, instar differs but little; E, pupa; F, imago.]