PAPILIONIDiE. 
347 
middle, and orange spots on the sides. They change their color at 
each moult and on reaching maturity are light green, with bold black 
bands, which partly enclose a number of bright yellow spots. Upon 
being disturbed, the larva protrudes a forked scent organ from just 
back of its head, which gives off a disagreeable odor. This organ is 
orange in color and by the manner in which it is used, one might 
suppose the insect to be venomous. Except, however, for the havoc 
which the insect sometimes makes in the vegetable garden, it is 
harmless. 
The caterpillars are exceedingly subject to the attacks of para¬ 
sites, and it frequently happens that from one hundred of them, one 
will obtain but half a dozen butterflies. 
An interesting account is given by Mr. Harris in his “-Insects 
Injurious to Vegetation” of the manner in which the larva of this 
species prepares for its change into the chrysalis state and its hatch¬ 
ing into the butterfly. He says,The caterpillars usually come to 
their full size between the 10th and 20th of July and then measure 
about one inch and a half in length. After this they leave off eat¬ 
ing, desert the plants, and each one seeks some sheltered spot, such 
as the side of a building or fence, or the trunk of a tree, where it 
prepares for its transformation. It first spins a little web or tuft of 
silk against the surface wheron it is resting, and tangles the hooks 
of its hindermost feet in it, so as to fix them securely to the spot; 
it then proceeds to make a loop or girth of many silken threads bent 
into the form of the letter U, the ends .of which are fastened to the 
surface on which it rests on each side of the middle of its body, and 
under this when finished it passes its head, and gradually works the 
loop over its back so as to support the bod}^ and prevent it from fall¬ 
ing downwards. 
“ Though it generally prefers a vertical surface on which to fasten 
itself in an upright position, it sometimes selects the under side of 
a limb or of a projecting ledge, where it hangs suspended, nearly 
horizontally, by its feet and the loop. 
“ Within twenty-four hours after it has taken its station, the cater¬ 
pillar casts off its caterpillar skin and becomes a chrysalis or pupa 
of a pale green, ochre yellow or ash gray color, with two short, ear¬ 
like projections above the head, just below which, on the upper part 
of the back, is a prominence like a pug nose. The chrysalis hangs 
in the same way as the caterpillar and remains in this state from 
nine to fifteen days, according to the temperature of the atmosphere, 
