MEANS OF DEFENCE OF. INSECTS. 255 
that this is altogether fabulous, since the animal has not 
the power of moving them?. Their use is still unknown. ° 
Whether the long and often tremendous horns on the 
head, thorax, and even elytra, with which many insects 
are armed, are beneficial to them in the view under con- 
sideration, is very uncertain. They are often sexual di- 
stinctions, and have a reference probably rather to sexual 
purposes and the economy of the animal, than to any 
thing else. They may, however, in some instances deter 
enemies from attacking them, and therefore it was right 
not to omit them wholly, though I shall not further en- 
large upon them.—Their mandibles or upper jaws, though 
principally intended for mastication,—and in the case 
of the Hymenoptera, as instruments for various econo- 
mical and mechanical uses,—are often employed to annoy 
their enemies or assailants. I once suffered considera- 
ble pain from the bite of the common water-beetle (Dy- 
tiscus marginalis, L.), as well as from that of the great 
rove-beetle (Staphylinus olens, F.); but the most tremen- 
dous and effectual weapon with which insects are armed 
—though this, except in the case of the scorpion, is also a 
sexual instrument, and useful to the females in oviposition 
—is their sting. With this they keep not only the larger 
animals, but even man himself, in awe and at a distance. 
But on these I enlarged sufficiently in a former letter”. 
These weapons, tremendous as they are, would be of 
but little use to insects if they had not courage to employ 
4 De Geer, i. 149— 
» Mr. MacLeay relates to me, from the communications of Mr. E, 
Forster, the following particulars respecting the history of Afutilla 
coccinea, L., which from this account appears to be one of the most 
redoubtable of stinging inescts. The females are most plentiful in 
Maryland, in the months of July and August, but are never very nu- 
