250 
H E MIP T E R A . 
the head upwards, and sticking by their flattened inferior 
surface closely to the bark. On attempting to remove them 
they are generally crushed, and there issues from tlie body 
a dark-colored fluid. By pricking them with a pin, they 
can be made to quit their hold, as I have often seen in the 
common species. Coccus Hesperidum^ infesting the myrtle. 
A little later the body is more swelled, and, on carefully 
raisino; it with a knife, numerous oblono; e^ss will be dis- 
covered beneath it, and the insect appears dried up and 
dead, and only its outer skin remains, which forms a convex 
cover to its future progeny. Under this protecting shield 
the young are hatched, and, on the approach of warm weath¬ 
er, make their escape at the lower end of the shield, which 
is either slightly elevated or notched at this part. They 
then move with considerable activity, and disperse them¬ 
selves over the young shoots or leaves. 
The shape of the young Coccus is much like that of its . 
parent, but the body is of a paler color and more thin and 
flattened. Its six short leo-s and its slender beak are visible 
O 
under a magnifier. Some are covered with a mealy powder, 
as the Coccus Cacti^ or cochenille of commerce, and the 
Coccus Adonidum^ or mealy bug of our greenhouses. Others 
are hairy or woolly; but most of them are naked and dark- 
colored. These young lice insert their beaks into the bark 
or leaves, and draw from the cellular substance the sap that 
nourishes them. 
Reaumur observed the ground quite moist under peach- 
trees infested Avith bark-lice, Avliich Avas caused by the drip¬ 
ping of the sap from the numerous ^junctures made by these 
insects. AVhile they continue their exhausting suction of 
sap, they increase in size, and during this time are in Avhat 
is called the larA^a state. When this is completed, the in¬ 
sects Avill be found to be of difterent magnitudes, some much 
larger than the others, and they then prepare for a change 
that is about to ensue in their mode of life, by emitting from 
the under side of their bodies numerous little AA'hite doAvny 
