THE SPINY OAK-WORM. 125 



Massachusetts. Here the white oaks were untouched and the red oak is not abun- 

 <lant. The food of the caterpillars was almost exclusively the foliage of the black oak 

 (Q. tinctoria), the scarlet oak {Q. coccinea), and the bear or scrub oak {Q. tlicifolia). 

 {See also American Naturalist, xvi, 914.) 



It was also abundant in September of the same year in Sagadahock 

 and Cumberland Counties, Maine, and in Rhode Island. 



The following notes on the egg and freshly-hatched larva are con- 

 tributed by Professor Riley : 



August 1, 1869, received of F. A. Gates, Massillon, Cedar County, Iowa, a ribbed 

 female of Dryocampa senatoria with a batch of over 300 eggs on the underside of a 

 raspberry leaf. These eggs are almost round in outline, depressed, being about half 

 as high as wide, the width across being .04 of an inch. The shell is so very trans- 

 parent that it makes a very good object for watching the development of the em- 

 bryo. The egg is when first laid yellow, with a darker brownish ring above. 



The larva when first hatched is pale yellow, with a large black head, black thoracic 

 legs and two stiff black horns springing with an anterior slant from the top of seg- 

 ment 2, each of which horns terminate in two finer bristles. The rest of the body is 

 covered with pale bristles. (Riley's unpublished notes.) 



Larva. — Head large, fully as wide as the body ; jet black. Body uniformly thick, 

 cylindrical. On mesothoracic segment a pair of long and slender, stiff, black spines, 

 blunt at the end, nearly as long as the body is thick. They stand erect, diverging a 

 little, and arise from swollen bases, connected by a slight transverse ridge. On each 

 succeeding segment there is a transverse series of four small, sharp, simple spines, 

 one or two sometimes ending iu two spines ; and low down on each side, below the 

 spiracles, are three large and a fourth minute short acute spine. 



There are on the hinder part of the back of most of the segments two small black 

 spines. The spines become larger on the last three, especially the penultimate seg- 

 ment. Supra anal plate large and flat, rather rough, ending in two acute spines, with 

 four smaller spines on each side. Abdominal legs larger and broad, with stiff short 

 hairs on the hinder and lower edge. 



Prothorax unarmed, but with a thickened conical plate. Body jet-black, with a 

 double dorsal ocher-yellow-brown line, a narrow subdorsal line, and two wavy lateral 

 lines of the same color. A median ventral ochre-brown band. Length, 42™™, 



Moth. — Male antennje broadly pectinated on basal two- thirds; yellowish-brown; 

 hase, costa, and outer edges bathed in faint purplish ; the hind wings of the male well 

 rounded ; fore wings slightly spotted with dark brown ; a clear large round white 

 discal spot ; an outer oblique distinct brownish line extending from a little beyond 

 the middle of the inner edge to the costa just before the apex. Expanse of wings 

 of male, 42"™ ; female, 57™™, 



169. The spiny oak-worm. 



Anisota stigma Hiibner. 



Eating the leaves in September, in the Southern States especially, a worm like the 

 preceding, but of a bright tawny or orange color, with a dusky stripe along the back 

 and dusky bands along the sides, and with its prickles lengthened into thorn-like 

 points. 



This worm is said by Dr. Riley to be nearly as destructive in the 

 Southern States as A. senatoria is in the Northern. 



According to Abbot and Smith, in Georgia the caterpillar goes into the 

 ground to pupate September 20 and comes forth by the middle of June 



