THE SILKY ASILUS. 605 



These insects belong to a family called Asilid^, from 

 Asilus, the principal genus. In the larva state, those of the 

 Asilians whose habits are known live in the ground upon 

 the roots of plants, and sometimes do considerable mischief, 

 as proved to be the case with some that were sent to me last 

 May, by the Rev. Thomas Hill, of Waltham, who found 

 them devouring the roots of the tart rhubarb. They were 

 yellowish-white maggots, about three quarter^ of an inch 

 long, not perfectly cylindrical, but a little depressed, and 

 tapering at each end. The head was small, brown, and 

 partially drawn within the first ring, and was provided with 

 two little horny brown hooks. There was a pair of breath- 

 ing-pores on the first ring, and another pair on the last but 

 one. These maggots were transformed in the earth to naked 

 pupae, having the limbs free. The pupa was brown, and 

 had a pair of short horns on the forehead, three spines on 

 each side of the head, a forked tail, and a transverse row 

 of little teeth across the middle of each ring of the hind 

 body. When about to undergo their last transformation, 

 the pupsB work their way to the surface of the ground by 

 the help of the little teeth on their rings. I have repeatedly 

 seen the empty pupa-shells sticking half-way out of the 

 ground around rhubarb plants. In the fore part of July, 

 there issued from these pupa3 some 



T Fig. 265. 



long-bodied flies, which proved to 

 be of the species called Asilus se- 

 riceus (Fig. 265) by Mr. Say. 

 The body of this insect is slender 

 and tapering, and measures from 

 eiffht tenths of an inch to one inch 

 and one tenth in length. It is of 

 a brownish-yellow color, covered 

 with a short silky down, varying 

 in different lights from golden yel- 

 low to brown, and with a broad brown stripe on the top 

 of the thorax. The wings are smoky brown, with broad 



