ARTICULATA. 141 



butterfly, AcJierontia atroj^os {pi. SO, fg. 15), produces a j^laintive ciy, 

 which is said to proceed from the head. "We have discovered that a sound 

 is made bv an American species o^ Lithosia (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 {pi. SO, 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 j^roductions cultivated by the farmer 

 and gardener make their apj)earance, 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 desti"oy the leaves and blossoms of plants, 

 as the larvfe of bntterflies ; the larvne of some Coleoptera., especially those 

 of some of the beetles {i^l. 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 np in large flakes. An instance is related of a fiirmer whose crops 

 were entirely destroyed by the larvsE of Melolontlia {pi. '^X., 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 

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

 eastern continent large tracts are sometimes rendered desolate l)y the 

 ravages of the large grasshopper, Locusta imgratona. The CurcuUonidm 

 (including the weevils) {p>l. SI, figs. 07-76) are destructive to various kinds 

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

 and dead wood ; Bostrichus., &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 eflfect this object, not only in cases where 

 the stamens and pistils, although together, present difflculties in the mode 

 of ^tting the pollen to the latter, but in those cases where the plants are 

 dioTCOus, 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 j^istils 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 larvae. The 

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



345 



