546 
HYMENOPTERA. 
icine, are caused by the punctures of the Cynips gallon 
tinctorice on a kind of oak growing in the western part 
of Asia ; and the insect may often he 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 resemble numerous 
small seeds, clustered together in the middle of a fruit. 
Two or three different kinds of insects are often found to 
come from one gall, namely, a few gall-flies, which are 
the lawful proprietors thereof, and more numei-ous four- 
winged flies (Ciiai.cidid.-e), 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 then- 
food, and thereby 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 
(Plate VIII. Fig. 9) 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 
Fig - ^ (Fig 253, magnified) lives in 
the kernel, becomes a chrysalis 
j (Fig. 254) in the autumn, when 
J- 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 Octo- 
ber. The name of this insect is Cynips conftuens.* (Plato 
* Diphkpis conjluentus of my Catalogue, and so named by Sir. Say. 
