T.. W. Harris on the Seventeen-year Locust. 221 
which the insects are subject, during the long period of their sub- 
terranean confinement, is an increase of size, and the more com- 
plete development of the four small scale-like prominences on their 
backs, which represent and actually contain their future wings. 
s the time of their transformation approaches, they gradually 
ascend towards the surface, making in their progress cylindrical 
passages, oftentimes very circuitous, and seldom exactly perpen- 
dicular, the sid@s of which, according to Dr. Potter, are firmly 
cemented and varnished so as to be water-proof. These burrows 
are about five-eighths of an inch in diameter, are filled below 
with earthy matter removed by the insect in its progress, and can 
be traced by the color and compactness of their contents to the 
depth of from one to two feet, according to the nature ef the soil ; 
but the upper portion to the extent of six or eight inches is emp- 
ty, and serves as a habitation for the insect till the period for its 
exitarrives. Here it remains during several days, ascending to 
the top of the hole in fine weather for the benefit of the warmth 
and the air, and occasionally peeping forth apparently to recon- 
-hoitre, but descending again on the occurrence of cold or wet 
weather. 
During their temporary residence in these burrows near the sur- 
face, the Cicada grubs, or more properly pupee, (for such they are 
to be considered at this period, though they still retain something 
of a grub-like form,) acquire strength for further efforts by expo- 
sure to the light and air, and seem then to wait for only a favor- 
able moment to issue from their subterranean retreats. When at 
length this arrives, they issue from the ground in great numbers 
in the night, crawl up the trunks of trees, or upon any other ob- 
Ject in their vicinity to which they can fasten themselves securely 
by their claws. After having rested awhile they prepare to cast 
off their skins, which, in the mean time, have become dry and 
of an amber color. By repeated exertions a longitudinal rent is 
made in the skin of the back, and through this the included Cica- 
da pushes its head and body, and withdraws its wings and limbs 
from their separate cases, and, crawling to a little distance, it 
leaves its empty pupa-skin, apparently entire, still fastened to the 
tree. At first the wing-covers and wings are very small an 
opake, but, being perfectly soft and flexible, they soon stretch out 
to their full dimensions, and in the course of a few hours the su- 
perfluous moisture of the body evaporates, and the insect becomes 
strong enough to ‘ly. ry j : 
During several successive nights the pupe continue to issue 
from the earth; above fifteen hundred have been found to arise 
beneath a single apple tree, and in some places the whole surface 
of the soil, by their successive operations, has appeared as full of 
holes as a honeycomb. In Alabama the species under considera- 
tion leaves the ground in February and March, in Maryland and 
Pennsylvania in May, but in Massachusetts it does not come forth 
