400 INSECTS INJURIOUS TO VEGETATION. 



tennse red, and the remainder black. It varies in being darker 

 sometimes, ad measures from one eighth to three sixteenths 

 of an inch in length. Great numbers of these galls- flies are bred 

 in the irregular woody galls, or long excrescences, of the stems of 

 rose-bushes. 



The small roots of rose-bushes, and of other plants of the 

 same family, sometimes produce rounded, warty, and woody 

 knobs, inhabited by numerous gall-insects, which, in coming out, 

 pierce them with small holes on all sides. The winged insects 

 closely resemble the, dark varieties of the preceding species, in 

 color, and in the little furrows on the thorax ; but their legs are 

 rather paler, and they do not measure more than one tenth of an 

 inch in length. This species has been named Cynips semipiceus. 



Monstrous swellings of buds, and various other kinds of ex- 

 crescences, may often be seen on plants ; but my specimens of 

 the insects producing them are not in a condition to be described. 

 The foregoing account, however, will serve to illustrate the hab- 

 its of some of our most common gall-flies, and explain the ori- 

 gin, forms, .and structure of their singular productions. Such 

 excrescences, as soon as they are observed on plants of any val- 

 ue, should immediately be cut off, and put into the fire. Fortu- 

 nately the parasitical insects, that live at the expense of the four- 

 winged gall-flies, are almost or quite as numerous as the latter, 

 and, as already stated, limit them in their powers of multiplication. 



