IIYMENOPTERA. 435 



cluster around the small twigs of the white oak, and her junc- 

 tures are followed by the growth of a rough or siiaggy reddish 

 gall, as large sometimes as a walnut. When this is ripe, it is 

 like brittle sponge in texture, and contains numerous little 

 seed-like bodies, adhering by one end around the sides of the 

 central twig. These seeming seeds have a thin and tough 

 hull, of a yellowish white color; they are egg-shaped, pointed 

 at one end, and are nearly one eighth of an inch long. The 

 gall-insects live singly, and undergo their transformations, 

 within these seeds; after which, in order to come out, they 

 gnaw a small hole in tiie hull, and then easily work their way 

 through the spongy ball wherein they are lodged. They are 

 less than one tenth of an inch long, are almost black, or of the 

 color of pitch, highly polished, especially on the abdomen, and 

 their mouth, antennae, and legs are cinnamon-colored. 



It has been observed that no tree in Europe yields so many 

 different kinds of galls as the oak. Those which I have de- 

 scribed are not all that are found on oaks in this country, and 

 they seem to be sufficiently distinct from the galls of European 

 oaks. 



Round, prickly galls, of a reddish color, and rather larger 

 than a pea, may often be seen on rose-bushes. Each of them 

 contains a single grub, and this in due time turns to a gall-fly, 

 which may be called Gijnips bicolor, the two-colored Cynips. 

 Its head and thorax are black, and rough with numerous little 

 pits; its hind body is polished, and, with the legs, of a brown- 

 ish red color. It is a large insect compared with the size of 

 its gall, measuring nearly one fifth of an inch in length, while 

 the diameter of its gall, not including the prickles, rarely ex- 

 ceeds three tenths of an inch. 



Cynips dicJdocerus, or the gall-fly with two-colored antennae, 

 is of a brownish red or cinnamon color, with four little longi- 

 tudinal grooves on the top of the thorax, the lower part of the 

 antennae red, and the remainder black. It varies in being 

 darker sometimes, and measures from one eighth to three six- 

 teenths of an inch in length. Great numbers of these gall-flies 

 are bred in the irregular woody galls, or long excrescences, of 

 the stems of rose-bushes. 



