DIPTERA. 485 



of Say, which is somewhat like the last, but has yellow hairs 

 on the tliree middle segments of the hind body, and on the 

 shanks of the anterior and middle pairs of legs, and measures 

 about an inch in length. These insects belong to a family 

 called AsiLiD.E, from Asiliis, 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 con- 

 siderable mischief, as proved to be the case with some that 

 were sent to me last May, by the Rev. Thomas Hill, of Wal- 

 tham, who found them devouring the roots of the tart rhubarb. 

 They v^ere yellowish white maggots, about three quarters of 

 an inch long, not perfectly cylindrical, but a little depressed, 

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

 partially draw^n within the first ring, and was provided with 

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

 pores on the first ring, and another pair on the last but one. 

 These maggots were transformed in the earth to naked pupse, 

 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 pupse 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 tlie fore part of July, there issued from these pupae some 

 long-bodied flies, which proved to be of the species called 

 Asilus sericeus, by Mr. Say. The body of this insect is slen- 

 der and tapering, and measures from eight 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 yellow to brown, and with a broad brown 

 stripe on the top of the thorax. The wings are smoky brown, 

 with broad brownish yellow veins, and expand one inch and a 

 quarter, or more. We have several other kinds of Asi/us, some 

 larger, and others smaller than the foregoing, of whose history 

 nothing is known, except their predaceous habits in the winged 

 state, which have been often observed. There are also several 



