246 



HALF HOUKS 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 frequcntlj' 

 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, 



