THE FOUR-WINGED GALL-FLIES. 543 



The outer side of the fourth and fifth joints of her antennae, 

 her knees, and a line on the outer edge of her shins, are 

 white. Her feet are dull red. Her wings are clear and 

 transparent, with a broad, smoky-brown, transverse band, 

 beyond the middle of the first pair. Her body measures 

 nearly six tenths of an inch in length. 



The dark-colored Oryssus is probably the same as one 

 described by Mr. Westwood, in 1835, in the fifth volume* 

 of " The Zoological Journal," under the name of Oryssus 

 Sayii, in honor of the late Mr. Say, who sent him the insect. 

 It is of a deep black color, rough before and smooth behind, 

 and is marked with white on the antennae and legs, like 

 the red-tailed kind, with the addition of two short white 

 lines on the forehead, between the lower corners of the 

 eyes. The feet are black. The wings have a smoky band 

 beyond the middle, which, however, fades away towards 

 the inner margin. I have seen only females of this species, 

 and they measure from four to five tenths of an inch in 

 length. 



It is possible that my Oryssus affinis, which is a male, 

 may be the mate of the foregoing dark-colored species, from 

 which it differs in having reddish feet, and in wanting the 

 two white spots on the forehead. It measures four tenths 

 of an inch in length. 



From this somewhat extended account, it is evident that 

 we have very- little power over the insects of the foregoing 

 family. The most that we can do towards checking their 

 ravages will be to destroy the females, whenever they are 

 found laying their eggs. 



The four-winged gall-flies have very little outward resem- 

 blance to the saw-flies and horn-tailed wood-wasps. They 

 agree with them, however, in boring into plants, and in 

 laying their eggs therein. Vegetation does not often suffer 

 much injury from their attacks, and it is only on account 

 of the very singular productions, called galls, arising from 



,* Page 440. 



