INSECTS. 281 
and tlie covering with which it surrounds itself a pupa- 
case or cocoon. It then undergoes a wonderful change, 
becoming the full-formed insect or imago — the ugly 
worm, that a short time previous had surrounded itself 
with a silken cocoon, bursting its case and flying off a 
gay, attractive and resplendent butterfly. From crawl- 
ing meanly over the ground or the foliage, leaving a 
slimy streak behind, or horrible with a greenish smooth 
body and clinging feet, or disgusting with innumerable 
bristles, it soars away, its gay plumage glittering in the 
sunlight as it flits from flower to flower, the envy and 
admiration of the human female sex. How much is 
there not in beauty ! 
Many insects live for years as worms, and but a few 
hours in their perfect state. The ejpJiemercB^ so called 
from appearing in the morning and dying before night, 
often do not reach half that age, although if the sexes 
are separated they will sometimes attain the great age 
of several weeks. They may be regarded as sacrificing 
their lives for the tender passion. They cover our waters 
in Summer, warmed into existence by the sun's rays, flit- 
ting in a graceful but inefficient way from place to place, 
or floating calmly upon the surface, dropping back into 
nonentity with the departing sunlight. They are some- 
times, especially in the southern country, quite large, and 
include what among fishermen are known as the May- 
flies. 
In some classes the change from the larva is not so 
remarkable, the worm having much of the appearance, 
and many of the distinctive marks of the perfect fly, 
as for example the bee ; in these the metamorphose is 
