268 AGRICULTURAL EXPERIMENT STATION. 



are never very prominent and the darker the general color of the 

 head, the less obvious they appear ; but usually the}^ can be made 

 out. There are four tufts of four or five hairs each on the head, 

 two on each side of the centre, one pair a little ahead of the other 

 and a larger tuft is at the base of each antenna. The antenna is 

 short and slender (fig. 4), light brown in color, paler at the base, 

 set with sparse stout spines and with more numerous very small 

 ones. Viewed from the side the antenna is slightly bi-sinuate, 

 i. e., it makes both an in and out curve on each margin. The tuft 

 is composed of from six to ten long hairs and is situated well be- 

 low the middle. The apex is a long and short spine, two bristles 

 and a little joint, all articulated to the main segment. The eyes 

 are black, of good size, somewhat kidney-shaped, and occupy the 

 widest part of the head. The central hairs of the rotary mouth 

 brushes are very finely comb-toothed or pectinated. The mentum 

 (fig. 6) is very constant, triangular in form, with from twelve to 

 fourteen teeth on each side of the apex, the toothed edges only 

 slightly curved. The mandible (fig. 5) is characteristic in form 

 and best described by a reference to the figure. The maxillary 

 part bearing the palpus has a large tuft of moderately long hair 

 and its inner surface is well clothed with hair arranged in rows 

 and patches. The thorax is angulated at the sides, one and one-half 

 times as broad as long, the dorsum^a little depressed and wrinkled, 

 each of the three lateral angles with a tuft of long- hair arising 

 from a tubercle, and two tufts of two hairs each, at the anterior 

 margin. Abdominal segments one to seven are oblong or sub- 

 quadrate in form, each with a lateral hair tuft which becomes 

 smaller and shorter posteriorly. The eighth segment has lateral 

 patches of from twenty-five to fifty elongated fringed scales (fig. 

 8), forty being the average number, arranged as shown in figure 

 7. These scales are approximately constant in all stages, but are 

 fewer in number and differently arranged in the smaller larvse. 

 The anal siphon is at least three times as long as broad (fig. 7), 

 and has two series of toothed spines (fig. 9), each series ranging 

 from sixteen to twenty-four in number, eighteen being about aver- 

 age. In the mature larva the color is like that of the body, but in 

 the early stages the tip is black. The ninth segment is sub-quad- 

 rate in outline, the dorsal part oA apical margin with two tufts in 

 each, of which one hair is much longer than the others ; the ventral 

 part of the margin with a barred area from which arise ten to 

 twelve tufts of from five to seven hairs each. The anal gills are 

 moderately long and not supplied with obvious trachea in the later 

 staees. 



