78^ REPORT UNITED STATES GEOLOGICAL SURVEY. 



" Tho larvae are 2^ lines long, of a whitish color, tapeiiug toward the head, composed 

 of twelve joiuts : on each side of the thoracic segment is a short branching spiracle, 

 and the tail is furnished with four divaricating blunt spines, the edges of the seg- 

 ments being serrated with hooked ones. When full grown this skin becomes horny, 

 changing to a rust color, the maggot is transformed to a pupa within an internal 

 horny shell of a chestnut color, and of course the pupa greatly resembles the larva. 



'' There is also an extensive group of flies called Borbonis, the larvae 

 of which live upon decomposing vegetables, and probably animal sub- 

 stances also; at all events they are generated in fungi. A portion of 

 these flies is now distinguished by Macquart, under the generic name 

 of Limosina ; one of them I have bred from rotting potatoes, and it 

 seems to be identical with that author's — 



"X. genicuJata. — It is only 1 line long, and expands a little more than 2 lines. It is 

 black ; the head is moderately large, with an ample cavity beneath to receive the 

 mouth; the eyes are hemispheric and rust-colored, and there are three minute ocelli 

 on the crown ; the face is concave, with two little horns in the center, the third joint 

 orbicular, with a tomentose seta; thorax broader, very convex; scutel semi-orbicular 

 and flat ; abdomen very short, the segments equal in length ; wings rather small, 

 smoky, nervures pitchy ; costal the strongest ; submarginal cell not extending to the 

 apex, second and third longitudinal nervures united at the middle, third and fourth 

 forming a looj) with two minute branches at the extremity ; balancers small and ocbre- 

 ous; legs pitchy; hips ochreous, as well aa the tips of the anterior thighs and the 

 base of the shanks ; hinder with a few spines outside ; feet long, live-jointed, especially 

 the hinder, which are slender and longer than the shanks ; dull ochreous, basal-joint 

 very long and pitchy, terminal one very short, and furnished with short claws. 



"M. Rayer also observed a species in the infected potatoes which has 

 been named by Gu6rin Limosina payenii, and it is not improbable that 

 it may be the male of Macquart's species, for it agrees very well with our 

 fpuiale, except in the color of the wings and the structure of the hinder 

 feet. 



" With the foregoing Diptera I often bred a parasitic insect in consid- 

 erable numbers, but to which it is attached, or whether to any of them, 

 I am unable to ascertain. It belongs to the order Hymenoptera, the 

 family Proctotrupid^, and the genus Cerapsilon, which has been 

 divided by Mr. Westwood into three genera, one of which is called 

 Faramesius, and to that section our insect belongs. It is included by 

 Nees ab Esenbeck in the genus Biapria^ and has been named by him — 



"P. brachialis. — The male is scarcely 1 line long aud expands If; it is very glossy 

 black ; the head is globose, the face short, ovate, and at the bottom are attached the 

 autennai, which are nearly as long as the body, ferruginous and fourteen-jointed, basal 

 joint long, second short, obovate, third notched or comma-shaped, remainder short and 

 obovatc, apical joint conical; eyes small, lateral, with three ocelli on the crown in a 

 triangle ; thorax very globose, scarcely larger than the head ; scutel small, semi-oval, 

 deeply hollowed at the base ; metathorax ferruginous and uneven ; petiole forming a 

 ferruginous knob, woolly behind ; abdomen small, ovate-conic, pitchy, base ferruginous, 

 with four longitudinal channels on a very large segment, apical segment very short; 

 fore wings dusky and pubescent, with a few nervures at the base of the superior, 

 forming an elongated cell ; six legs short, slender, and ochreous, pitchy at the base; 

 thighs thickened, as well as the anterior shanks, and pitchy at the middle ; feet slender, 

 tive-jointed, tips dusky. Female: Above 1 line long, aud expanding If; this sex is 

 not only distinguished by its larger size, but the horns are shorter, with only twelve 

 joints, the third being simple like the second; and the extremity of the abdomen is 

 acuminated, and very acute. 



"This insect belongs to a family which is very serviceable in keeping 

 down wire-worms and other subterranean larvse, as will be seen by a 

 reference to a former chapter and the Gardener's Chronicle. Nees also 

 says that the Diaprice breed in the subterranean larvae of TipulWj or 

 gnats. 



" I must not omit to record another fly, called Biloplms febrilis^ which 

 is exceedingly abundant every year, the larvae causing much mischief 



