ARTICULATA. 141 



butterfly, AcTierontia atropos {pi. SO, fig. 15), produces a ])laintive crv, 

 which is said to proceed from the head. We liave discovered tliat a so^^nd 

 is made bj an American species of Lithosia (another nocturnal le[>idopter) 

 bj vibrating the sides of the thorax ; and we have heard a ^'ery low and 

 dull musical sound from the hemipterous genus Belostorna {jjl. SO, Jig 71), 

 l)roduced apparently by a vibration within the thorax, and from the lov;- 

 ness of the note produced, a largo portion of the organs nu^st 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 

 thej exceed these in the importance of their history. Almost every year 

 new enemies to the various vegetable j^roductions 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 larvffi of butterflies ; the larvie of some Coleopfe7'a, especially those 

 of some of the beetles (j:)!. 81, fig. 130), 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 ftirmer whose crops 

 were entirely destroyed by the larvjB of Mdolontha {pi. ^1., fig. 130), of 

 which eighty bushels were collected. At one time the cultivation of the 

 suo-ar cane had to be abandoned on account of the increase of an ant 

 {Fopinica saccharivora)^ which destroyed all the plantations ; and on the 

 eastern continent large tracts are sometimes rendered desolate by the 

 ravages of the largo grasshopper, Locusta migratoria. The CurculionUIce 

 (including the weevils) {p>l. SI, figs. 67-76) are destructive to various kinds 

 of grain and seed; the CerambycidcB {pi. 81, fig. 50, ifec.) destroy growing 

 and dead wood ; BostricJius., &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 wheB^ 

 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 nseful in destroying those which feed upon 

 vegetables, and they attack both the perfect insects and their larva?. The 

 parasitic families destroy an immense number of caterpillars, and the larvag 



345 



