CLASS I. INSECTA: ORDEE 1. COLEOPTERA. 
551 
grayish-brown creature, rather more than half an inch long, and quite destitute of wings. The 
male, on the contrary, is active, and 
flies Avell ; and the luminosity of the 
female appears to be intended to at- 
tract her ^'olatile companion. The 
light proceeds from the under part of 
the abdomen and near the tip, and 
the animal appears to have the pow- 
er of varying its intensity. If this 
luminous portion be removed, it re- 
tains its illuminating property for 
some time. If the glow-worm be im- 
mersed in warm water, it emits a bril- 
liant light ; if placed in cold water, its 
light is extinguished. 
The larvae of some species of the 
genns Clerus live parasitically in the 
nests of bees and wasps, feeding upon 
their larvse. 
THE GLOW-WOEM. 
THE HETEEOMEEA. 
THE SPANISH FLY. 
This term is from the Greek heteros, dissimilar, and jnera, divisions ; it includes several genera, 
the spines having four joints in the posterior tarsi, and five in the other four feet. 
THE TRACHELIA. 
The Trachelia are generally active diurnal insects, frequently adorned with gay colors. Their 
bodies are often soft, the elytra flexible, and sometimes much shorter 
than the abdomen. To this tribe belongs the Blister or Spanish 
Fly, Lytta vesicatoria, the important medicinal uses of Avhich, under 
the name of Cantharides, are so well known. These insects are com- 
mon in the south of Europe, and are especially abundant in Spain, 
Avhere they are taken in large numbers, and from which source the 
best are generally obtained. They feed principally upon the ash. 
Many other insects belonging to this tribe, also contain a substance 
which has the efi"ect of raising blisters when applied to the skin ; and 
these are employed in their native countries in place of the Lytta vesicatoria. The species of 
MeloBy several of which are found in Great Britain, possess this property ; which, however, seems 
in all cases to increase in intensity in proportion to 
the heat of the country in which the insects live. 
The species of Meloe are soft, sluggish beetles, 
^-'^ \ I " ■ i '"^^3^*?^'^-=^!^rSfe^^^^^^^ with short elytra and no wings, and may be 
S^, found crawling about among the grass, in v/arm, 
sandy places in the early summer. The young 
larvse, on first leaving the egg, attach themselves 
to wild bees, and it is supposed that they are after- 
ward parasitic upon the bee larvas. In this country 
the Epicauta vittata, often called the Potato Fly, 
as well as other species, have the power of raising 
blisters and may be used for this purpose. 
The curious JRipiphorus paradoxus — a small 
beetle, also belonging to this group — is parasitic iu the nests of the common wasp ; and many 
other species appear to be parasitic in their larva state. One of the most beautiful of the Euro- 
THK PTROCHROA RUBENS. 
