142 SOCIAL HABITATIONS, 
Before we close the subject of parasites, it will be 
needful to give a brief account of one or two parasitic 
insects which possess points of peculiar interest in the 
habitations which they make, or in the places wherein 
they find their abode. 
One of these insects is a rather pretty beetle, termed 
Clerus alvearius. In its perfect state it is innocent 
enough, but in its larval state it is so destructive among 
the hives, that all bee-keepers will do well to destroy 
every Clerus that they can catch. It is generally to be 
found on flowers, licking up their sweet juices by means 
of a brush-like apparatus attached to the mouth. The 
wing-cases of most of the species are bright red, barred 
or spotted with purple. 
The larva is of a beautiful red, and is hatched from 
an egg placed in the cell occupied by the bee-grub. 
As soon as it is hatched, it proceeds to feed upon the 
bee-grub, and devours it. Unlike many insects with 
similar habits, it is not content with a single grub, but 
proceeds from cell to cell, devouring all their inhabitants. 
When it has eaten to the full, it conceals itself in the 
cell, and spins a cocoon of rather small dimensions in 
comparison with its own size. In process of time, it is 
developed into a perfect insect, and then breaks out of 
its cocoon and leaves the hive, secure from the bees, 
whose stings cannot penetrate the horny mail in which 
it is encased. 
There is another beetle which is parasitic upon snails, 
and which, in its larval and pupal states, is only to be 
found within those molluscs. Its scientific name is 
Drilus flavescens, the latter name being given to it in 
honour of its yellow-tinted wing-cases, which present 
a pretty contrast with the black thorax. It is a little 
