THE CELERY CATERPILLAR. 
21 
The larva. — The young stages of the larva are totally dissimilar 
to the mature ones. Five distinct stages are recognized, the second 
of which is illustrated at e, figure 5. This caterpillar is shown, 
lateral view, in figure 5, a. It is usually green, sometimes yellowish, 
and strongly ringed with velvety black and spotted as figured. 
Another caterpillar is shown at b to illustrate the appearance of the 
head and the peculiar yellow scent organs (osmateria). These are 
protruded when the insect is disturbed, and they exhale a pungent 
odor, similar to that of the bruised leaves of their food plants but of 
greater intensity and very disagreeable. 
The adult. — The parent insect is one of the swallowtail butterflies 
known by various names, but more commonly as the black swallow- 
tail. The ground color is velvety black, relieved by yellow bands in 
Fig. 5.— The celery caterpillar (Papilio polyxenes): a, Full-grown larva, side view; b, view showing 
head with extruded osmateria; c, male butterfly; d, egg in profile; e, young larva; /, suspended chrysalis. 
All about natural size, except d, which is much enlarged. (Original.) 
the male, as shown in the illustration (fig. 5). The hind wings are 
ornamented on the inside by eyelike markings resembling those of 
the male peacock, and they terminate in the " tails," from which the 
insect derives its common name. The female (fig. 6) is of larger 
size, somewhat faded black, and in every way of a more somber 
appearance than her spouse — a rule which holds good for most 
butterflies. Many of the yellow spots, particularly those arranged 
in the form of bands, are wanting, and the hind wings are ornamented 
with pale blue scales on the posterior half. This species is subject 
to every conceivable variation in color. The wing expanse is usually 
3 inches or a little more. 
The chrysalis. — The chrysalis is of a dull gray color, mottled with 
black and brown, and measures a little less than 1^ inches (see fig. 5,/). 
