814 INSECTA. 
element more suited to their future existence. The coccenelfe and others fix 
themselves by the anus under leaves or twigs; others suspend themselves by 
a silken thread; and a very great number enclose themselves in cases or 
cocoons composed of silk and other materials, to undergo their final change. 
The second form in which insects appear is the pupa or nympha state. In 
this, the number of the exterior organs of the animal is augmented or 
developed anew. lLinneus presents the forms under which insects appear 
in this state under five heads. The whole, however, may be reduced under 
two heads: first, those in which the transformation is partial ; and secondly, 
those in which it is complete. 
The influence which the partial metamorphosis exercises on the body is not 
sufficiently powerful to destroy the typical form proper to the species, and is 
modified only by slight alterations. An experienced eye which has seen the 
animal in its first stage of life, can still recognise the individual. The prin- 
cipal change takes place in the exterior members, and particularly in the 
organs of locomotion; but the animal retains its habits and activity. In 
the perfect or complete transformation, on the contrary, the larva is so 
different from the perfect animal, that nothing but ocular evidence of the 
change can convince of its identity. The pup of this metamorphosis, 
although their forms are shortened, and somewhat similar to those which 
they are to acquire in their last change, take no food, remain immoveable. 
and give no external sign of life. The term chrysalis is applied by mant 
writers to insects in the pupa state. The period insects continue in the 
pupa state is various. Some species remain only a few days und>r thie 
form, others as many months, or even years. Each, however, has in gene 
ral a stated period, which is seldom or never exceeded. As Lamarck has 
observed, there seems between the insect races and -the vegetable kingdon 
a correspondence of developement. The larve areproduced from the ove 
when the food of many, the leaves of plants, begin to appear; and the per 
fect insect from the same larve, as in a great portion of some orders, appears 
in its changed form, when food adapted to the animal is prepared in the nec- 
taries of the expanded flowers. The duration, however, of the pupa state, 
may be prolonged in certain cases, beyond the average term. Thus it has 
been found, that according as the insect becomes a pupa at an earlier or 
Jater period of the season, it will remain in this state for a few weeks or 
several months, according to circumstances. 
The caterpillar of the Papilio machaon, one of those which have a double 
brood in the year, if it becomes a pupa in July, the butterfly will appear in 
thirteen days; if not until September, it will not make its appearance unt. 
June, in the following year. The same is the case with a vast number of 
other insects, and their developement has been thus discovered to depend 
much on the temperature of the season, or, which is the same thing, on the 
developement of plants destined to afford them protection and support. In 
the month of Januiwy Reaumur placed several of the pupe of moths and 
