552 Insects. 
THE CHEESE MITE. (Acarus siro.) 
These destructive little creatures differ from spiders in 
having the thorax and abdomen united and covered with 
the same skin, though it is contracted in one part. They 
have also, when j T oung, only six legs, though the two 
others appear afterwards ; and their feet are armed with 
strong hooks, which enable them to retain hold of the 
cheese or other food, in which they take up their abode. 
Their bodies are covered with hair, and their mouths 
are furnished with strong mandibles, with which they 
soon hew down huge rocks and mountains of cheese. 
The eggs of these Mites are so small, that it has been 
computed that a pigeon's egg would contain thirty mil- 
lions of them. It must be observed that this Mite is 
only found in dry cheese, in which it looks like reddish 
dust. The cheese-hopper, found in moist rotten cheese, 
is the maggot of a kind of fly. (Piophila Casei.) 
§ IV. Insects. 
Insects have all six legs and two antennas or feelers ; 
and though the transformations they undergo differ 
slightly in the different kinds, the following is the order 
in which they occur : — The perfect insect lays eggs, 
which when hatcheM produce larvae ; and which are called 
grubs when they belong to beetles, maggots to flies, and 
caterpillars to butterflies and moths. These larvae eat 
voraciously ; and as they rapidly increase in size, they 
generally moult, that is, change their skins, two or three 
times. When the larvae are full grown, they go into the 
pupa state, in which they remain torpid and without 
food for a considerable length of time, sometimes first 
spinning a loose covering for the pupa called a cocoon. 
The pupa is generally called a chrysalis ; but it is also 
sometimes called a nymph, and sometimes an aurelia. 
The last transformation is when the insect breaks from 
its covering in a perfect form, when it is called the 
