DIPTERA. 417 



young of some of these insects. Swellings, or galls, as large as a 

 walnut, are often seen on the stems of some of our native Asters 

 or starworts. They are caused by the punctures of a fly, which 

 lays its eggs, singly, in the stem, when the latter is tender. The 

 puncture is followed by a spongy swelling, wherein the maggot, 

 hatched from the egg, lives, and passes through its transforma- 

 tions. The insect finally comes out in the fly state, through a 

 small hole previously made in the gall by the maggot. This fly 

 maybe called the gall-fly of the starwort (Tephritis Asteris). 

 Its body is about one fifth of an inch long ; it is of a light yellow- 

 ish brown color, with paler legs ; the wings are broad, rounded 

 at the tip, and clouded with brown in large spots, forming three 

 wide, irregular bands across them. 



Many of the smallest flies, belonging to several other groups, 

 are placed near the end of the order. One of them has a head 

 like a hammer-headed shark, short and very wide, with large glob- 

 ular eyes on each side of it. This little insect has been found, 

 in considerable numbers, flying near the ground, on the edges of 

 banks. It is the Sphyracephala brevicornis of Mr. Say, and is 

 figured and described in the third volume of his "American En- 

 tomology." The well known cheese-maggots are the young of a 

 fly {Piophila casei), not more than three twentieths of an inch 

 long, of a shining black color, with the middle and hinder le gs 

 mostly yellowish, and the wings transparent like glass. Some 

 minute flies, belonging to a family called Oscinid^:, are found to 

 be very injurious to wheat, rye, and barley, in Europe. One of 

 them (Oseinis frit), a shining black fly, with yellowish feet, and 

 measuring about one tenth of an inch in length, lays its eggs in 

 the blossoms of barley, the grains of which afterwards perish in 

 consequence of the depredations of the maggots of this fly ; and 

 Linnaeus states that a tenth part of the produce of the barley in 

 Sweden is thereby annually destroyed. The larva? or maggots of 

 Oscinis lineata, Chlorops pumilionis, Chlorops glabra, and other 

 flies allied to them, live within the lower part of the stems of 

 wheat, rye, and barley, thereby impoverishing the plants, and 

 causing them to become stinted in their growth. They are rather 

 larger insects than the frit-fly, and they have black and yellow 

 stripes on the thorax. It is highly probable that some of these 



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