IMPERFECT SOCIETIES OF INSECTS. 297 
Bombay, as he was playing at chess one evening with a friend in Old 
Woman’s Island, near that place, witnessed an immense flight of bugs 
(Geocoris@) which were going westward. They were so numerous as to 
cover every thing in the apartment in which he was sitting. When staying 
at Aldeburgh, on the eastern coast, 1 have, at certain times, seen innume- 
vable insects upon the beach close to the waves, and apparently washed up 
_ py them. Though wetted, they were quite alive. It is remarkable, that 
of the emigrating insects here enumerated, the majority —for instance, the 
jady-birds, saw-flies, dragon-flies, ground-beetles, frog-hoppers, &c. —are 
not usually social insects, but seem to congregate, like swallows, merely 
for the purpose of emigration, What incites them to this is one of those 
mysteries of nature, which at present we cannot penetrate. A scarcity of 
food urges the locusts to shift their quarters, and too confined a space to 
accommodate their numbers occasions the bees to swarm ; but neither of 
these motives can operate in causing unsocial insects to congregate. It is 
still more difficult to account for the impulse that urges these creatures, 
with their filmy wings and fragile form, to attempt to cross the ocean, and 
expose themselves, one would think, to inevitable destruction. Yet, 
though we are unable to assign the cause of this singular instinct, some of 
the reasons which induced the Creator to endow them with it may becon- 
jectured. This is clearly one of the modes by which their numbers are 
kept within due limits, as, doubtless, the great majority of these adventurers 
perish in the waters. Thus, also, a 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 {rom our own shores, and fallinginto 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 whicl 
feed together: these are of two descriptions ; those that associate in their 
first or last state ovly, and those that associate in all their states, The 
first of these associations is often very short-lived ; a patch of eggs is glued 
toa leaf; when hatched, the little larvae 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, regardless of the fate or lot of his brethren. Of 
this kind are the larva: of the saw-fly of the gooseberry, whose ravages I 
have recorded before, and that of the cabbage butterfly ; the latter, how- 
ever, keep longer together, and seldom wholly separate. In their final 
state, I have noticed 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. Towards the latter end of last July, 
walking through a wheat-field, I observed that all the blossoms of Convol- 
vulus arvensis, though very numerous, were interiorly turned quite black 
1. the infinite number of these insects, which were coursing about within 
hem, 
But the most interesting insects of this order are those which associate 
