HYMENOPTERA. 397 



round, and the thick, fringe-like projections on their surface short- 

 en, and take the appearance of leathery prickles. They have been 

 given as a medicine to expel worms ; and their efficacy, if they 

 really have any, probably depends upon the resin and oil pecu- 

 liar to the tree, which gives to the galls, even when dried, some- 

 what of a turpentine' smell. The round and hard Aleppo galls, 

 or nutgalls of commerce, used in the making of ink, in coloring, 

 and in medicine, are caused by the punctures of the Cynips gallon 

 tinctoricB, on a kind of oak, growing in the western part of Asia ; 

 and the insect may often be found in those which are not pierced 

 with holes. Some galls contain only a single insect, lodged in a 

 little cavity in the centre ; other kinds are inhabited by several 

 grubs, each in a cell by itself, and the cells not unfrequently re- 

 semble numerous small seeds, clustered together in the middle of 

 a fruit. Two or three different kinds of insects are often found 

 to Gome from one gall, namely a few gall-flies, which are the law- 

 ful proprietors thereof, and more numerous four-winged flies 

 (Chalcidid^), with elbowed antennae. The latter are bred 

 from grubs, which devour the grubs of some of the gall-flies, or 

 starve them by eating up their food, and therfeby contribute to 

 check the too great increase of the gall-flies. 



The largest galls found in this country are commonly called 

 oak-apples. They grow on the leaves of the red oak, are round 

 and smooth, and measure from an inch and a half to two inches 

 in diameter. This kind of gall is green and somewhat pulpy at 

 first, but, when ripe, it consists of a thin and brittle shell, of a 

 dirty drab color, enclosing a quantity of brown spongy matter, 

 in the middle of which is a woody kernel about as big as a pea. 

 A single grub lives in the kernel, becomes a chrysalis in the au- 

 tumn, when the oak-apple falls from the tree, changes to a fly in 

 the spring, and makes its escape out of a small round hole which 

 it gnaws through the kernel and shell. This is probably the usual 

 course, but I have known this gall-fly to come out in October. 

 The name of this insect is Cynips conjluentus.* Its head and 

 thorax are black, and rough with numerous little pits and short 

 hairs ; the hind-body is smooth, and of a shining pitch color ; the 



* Diplolepis conjluentus, Harris. " Catalogue." 



