IMPERFECT SOCIETIES OF INSECTS. 13 
great supply of food is furnished to those fish in the sea 
itself, which at other seasons ascend the rivers in search 
of them; and this probably is one of the means, if not 
the only one, to which the numerous islands of this globe 
are indebted for their insect population. Whether the 
insects I observed. upon the beach wetted by the waves, 
had flown from our own shores, and falling into the water 
had been brought back by the tide; or whether they had 
succeeded in the attempt to pass from the continent to us, 
by flying as far as they could, and then falling had been 
brought by the waves, cannot certainly be ascertained ; but 
Kalm’s observation inclines me to the latter opinion. 
The next order of imperfect associations is that of 
those insects which feed together :—these are of two de- 
scriptions—those that associate in their jist or last state 
oniy, and those that associate in all their states. ‘The 
first of these associations is often very short-lived: a patch 
of eggs is glued to a leaf; when hatched, the little larvee 
feed side by side very amicably, and a pleasant sight it is 
to see the regularity with which this work is often done, 
as if by word of command; but when the leaf that served 
for their cradle is consumed, their society is dissolved, 
and each goes where he can to seek his own fortune, re- 
gardless of the fate or lot of his brethren. Of this kind 
are the larvee of the saw-fly of the gooseberry, whose ra- 
vages I have recorded before*, and that of the cabbage- 
butterfly ; the latter, however, keep longer together, and 
seldom wholly separate. In their final state, I have no- 
ticed that the individuals of Thrips Physapus, the fly that 
causes us in hot weather such intolerable titillation, are 
very fond of each other’s company when they feed. To- 
@ Vor, I. 4th Ed. 196. 
