ARTICULATA. 141 
butterfly, Acherontia atropos (pl. 80, fig. 15), produces a plaintive cry, 
which is said to proceed from the head. We have discovered that a sound 
is made by an American species of Lthos¢a (another nocturnal lepidopter) 
by vibrating the sides of the thorax; and we have heard a very low and 
dull musical sound from the hemipterous genus Belostoma (pl. 80, fig 71), 
produced apparently by a vibration within the thorax, and from the low- 
ness of the note produced, a large portion of the organs must be concerned 
in producing it. 
The relations of insects to man are more numerous and important than 
those of the other classes of animals excepting the domestic breeds, and 
they exceed these in the importance of their history. Almost every year 
new enemies to the various vegetable productions cultivated by the farmer 
and gardener make their appearance, the history of which must in many 
cases be known before the proper means can be taken to prevent their 
increase. Often the noxious insect has a destroyer in some other insect, 
and the latter, being seen about the infested vegetable, is often mistaken for 
the real enemy. Some insects destroy the leaves and blossoms of plants, 
as the larvee of butterflies; the larvee of some Coleoptera, especially those 
of some of the beetles (pl. 81, fig. 1380), are very destructive to the roots 
of grass, which they sometimes destroy to such an extent that the sod can 
be taken up in large flakes. An instance is related of a farmer whose crops 
were entirely destroyed by the larvee of ALelolontha (pl. 81, fig. 130), of 
which eighty bushels were collected. At one time the cultivation of the 
sugar cane had to be abandoned on account of the increase of an ant 
(Lormica saccharwora), which destroyed all the plantations; and on the 
eastern continent large tracts are sometimes rendered desolate by the 
ravages of the large grasshopper, Locusta migratoria. The Curculionide 
(including the weevils) (pl. 81, figs. 67-76) are destructive to various kinds 
of grain and seed; the Cerambycide (pl. 81, fig. 50, &c.) destroy growing 
and dead wood; Lostrichus, &c., perforate the bark; and the Aphides and 
other families suck the sap; so that amongst the various orders, all parts of 
a plant, from the root to the seed, whether living or dead, are subject to 
destruction. 
Insects are frequently useful to plants in bringing the pollen to the 
pistils, and thus securing the continuance of the species in cases where 
this could not be effected except by such extraneous means. The insects 
which feed upon honey and pollen effect this object, not only in cases where 
the stamens and pistils, although together, present difficulties in the mode 
of getting the pollen to the latter, but in those cases where the plants are 
dioicous, when it sometimes happens that the staminate and pistillate flowers 
are several miles apart. Moreover, the stamens and pistils often arrive at 
maturity at different periods in the same blossom, so that the ripe pollen is 
carried upon the hairy body and limbs of the insect to the mature pistils of 
a different tree. 
The predaceous insects are useful in destroying those which feed upon 
vegetables, and they attack both the perfect insects and their larve. The 
parasitic families destroy an immense number of caterpillars, and the larvee 
345 
