736 REPORT UNITED STATES GEOLOGICAL SURVEY. 



each side as well as the penultinate, which, with the apex, is covered 

 with radiating bristles. The pupa is li liue loug; it is iuclosed iu the 

 skiu of the larva, and little depressed, aud yellowish-browu ; from the 

 thorax projects a branched spiracle like a buck's horn, aud the tail has 

 a stotit spine. It remains from a week to a fortnight in this state, and 

 the flies are often exceedingly abundant iu the autumn. 



"Two large species of flies belongiug to the family MusciDJE I also 

 bred from a single potatoe, as previously stated. There were forty-eight 

 specimens of one which was named by Falleus — 



"Musca stahuJaus. — The male is 3J lines long, and the wings expand i an inch ; it is of 

 an ash-color, and clothed vrith black bristles ; the feelers are ferruginous ; the anten- 

 na? drooping, five-pointed, and rust-colored, pitchy at the base, third joint elliptical 

 and heavy, except at the base ; the seta black and feathery, the basal joint minute ; 

 eyes large, approximating, naked, and chestnut color, the margins silvery white as 

 well as the face, with a black stripe tapering from the antennie to the three ocelli on 

 the crown ; thorax hoary, with four black longitudinal stripes before, the two central 

 ones the longest, with a spot on each side beyond the center ; scutel hoary, with a 

 dark stripe at the base, ferruginous at the tip ; abdomen ashy-ochreous, shining, the 

 back variegated with brown patches ; wings with the apical cell not angulated, but 

 suddenly rounded, scales at the base with pale tawny margins, and concealing the 

 ochreous-clubbed balances ; legs black, apex of thighs and tibiae ferruginous ; pulvilliat 

 the extremity of the feet elongated. Female similar, but the eyes do not approximate, 

 the face has a yellow tinge, and the stripe on the crown is broad and elliptical ; the 

 abdomen is broader, with an oviduct at the tail, and the pulvilli are small. 



" The maggots had bred aud accumulated among the slimy matter of 

 the rotting potato, just as meat-maggots are found, together with the 

 horny pupte. Indeed, the largest maggots were exceedingly like those of 

 the flesh-flies, being flat aud whitish, the ochreous food aud white lines of 

 viscera shining through the transparent skiu ; the head was pointed 

 with a black proboscis formed of two horny claws, aud the two spiracles 

 at the blunt tail were like two black horny knobs. The tough and oval 

 pupiB were of a bright chestnut color, the segments slightly marked, 

 the head end rounded and wrinkled to a point 5 the tail furnished with 

 two black specular tubes. 



" Of the other fly 1 bred fifty-eight specimens from the same potato in 

 the middle of August. The larvae escaped my notice at first from being 

 so very like the earth in color, and they are still more difficult to detect 

 from their sluggishness. They must be in the greatest force in July, but 

 I have met with them iu rotten potatoes in the end of Kovember. The 

 group of flies with these siugularly spiny larvae have been formed by 

 Bouche into a genus called Homalomia, being ^. section of Ant homy ia. 

 The parent fly of our species is exceedingly like Musca cunicularis of 

 Linn feus ; still there are difterences, and as the larvie are also dissimilar, 

 I have named this potato-fly — 



" Avthomyia tuherosa. — The male'm 2| lines loi g, and expands 5^; it is grayish-black 

 and bristly ; the eyes are chestnut color, naked, approximating on the crown, the inner 

 margin silvery white ; antennte drooping, five jointed, third j(nnt oblong, fourth a 

 slender elongated basal joint to the longish pubescent seta; thorax with five indis- 

 tinct broad stripes down the back, second and third abdominal segments with bright 

 ocherous spots on each side, third rarely with two similar minute spots; wings trans- 

 parent, nervnres dark, the two transverse ones not very remote ; balancei's jtale tawny ; 

 legs black, base of shanks indistinctly ferruginous. Female, ashy slate-color; the 

 eyes smaller than those of the male and remote ; the face not silvery ; thorax with 

 five distinct broad blackish lines down the back ; abdomen ovate-conic, with two indis- 

 tinct ocherous sllghtly-diaphauous spots on the second abdominal segment ; in other 

 respects this sex is similar to the male. 



" The larvce, although indolent, can crawl well ; they are of a dull 

 tawny color, clothed with long bristly spines, somewhat depressed, 

 elliptical, tapering to the head, which is waved about, aud when thrust 

 out is whitish and fleshy, armed with two minute hooks like ebony, aud 



