246 
HALF HOUES WITH INSECTS. [Packard. 
Fig. 185. 
have become moulded into a comparatively inflexible mode 
of life, when the creature is governed by what commonly 
goes under the name of “instinct,” a term too frequently 
used to cover our ignorance and stifle free inquiry into the 
origin of the different 
psychological traits of 
different races of ani¬ 
mals. 
The leaves of the oak 
are often ravaged by 
the young of the sen¬ 
atorial moth, a gayly 
caparisoned caterpillar, 
with two horns arising 
directly behind the head. 
It is nearly two inches in 
length, black, with four 
yellow stripes along the 
back, and two on each 
side. It lives in clus-’ 
ters on the trees, some¬ 
times well nigh stripping 
them of leaves in Sep¬ 
tember and October, the 
large, handsome moth 
appearing in July. 
Many pretty and curi¬ 
ous moths pass their pre¬ 
paratory stages of existence on the oak, and it is the food 
plant of the American silk worm (Fig. 185). The acorn is 
infested by the grub of a long-snouted weevil, like that which 
infests the chestnut (Fig. 186). Riley finds that in the 
Western States this grub so infests the acorns or mast as to 
diminish seriously the crop which is largely fed to swine. 
To show the economy of nature and her care not to waste 
22 
American Silk Worm. 
