THE LOCUSTS 



127 



AUDITORY APPARATUS OF GRASSHOPPER. 



figure showing position of apparatus, a, tympanum . B, external surface of 

 apparatus (.left outer ear) : a, opening of the stigma in the raised rim of the 

 tympanum; 6, the larger horny projection seen through the semi-trans- 

 parent tympanum ; c, the smaller horny projection. 



their companions. The Acridiidse are provided with peculiar organs to which we may with some 

 confidence ascribe auditory functions. These are two apertures of considerable size situated in the 

 first segment of the abdomen, closed by a membrane stretched upon a chitinous ring, and having upon 

 its inner surface certain chitinous pieces, one of which terminates in a delicate vesicle filled with a 

 transparent fluid, and terminating in two branches. A nerve proceeding from the metathoracic 

 ganglion runs to this apparatus, forms a ganglionic swelling in juxtaposition with the membrane, 

 and another in contact with the delicate vesicle, and both these ganglia 

 give origin to fine nervous rods such as are characteristic of sense- 

 organs. From the structure of this complicated apparatus there seems 

 to be no doubt about its function, 

 which, however, was long a puzzle to 

 entomologists. 



The food of the Acridiidse appears 

 to be exclusively of a vegetable nature, 

 and in accordance with this we find that the 

 gizzard is not developed. The insects are, 

 however, exceedingly voracious, and when 

 they occur in great numbers, as in the well- 

 known invasions of Locusts, they do much 

 damage in cultivated ground. They generally 

 possess great leaping powers, and also fly much 

 better than most of the other Saltatoria, 

 although, as a rule, their flights are of short 

 duration. Many of the larger species, however, rise to a considerable height in the air, and fly to 

 greater distances. 



As already stated, the female Acridiidae possess no exserted ovipositors, but they nevertheless 

 deposit their eggs in the ground in regular cavities prepared for their reception, and in the formation 

 of these receptacles the parts homologous with the valves of the ovipositor in the Locustidse play an 

 important part in conjunction with the pair of organs representing the cerci. The former arc 



hook-like pieces turned downwards, and when the insect is about 

 to deposit her eggs she brings these together and forces them into 

 the surface of the ground at the selected spot, and then, by 

 the strong muscular action of the abdomen, aided by these valves 

 and the superior tails, she gradually forms a hole nearly large 

 enough to contain the whole of her abdomen. During this process 

 the insect stands upon the four front legs, the hind legs being 

 lifted up out of the way, and as the abdomen, when being pushed 

 into the ground under these circumstances, is necessarily some- 

 what curved, the cavity formed for the eggs is also curved in the 

 same degree. When the receptacle is completed, the eggs are de- 

 posited in it, together with a quantity of a peculiar frothy secretion, 

 produced by glands at the apex of the abdomen, which afterwards 

 hardens, and forms a sort of packing for the eggs, enclosing each 

 of them in a separate cell. The eggs, which are of comparatively 

 large size, are carefully packed away in their nest in such a 



manner that the heads of the young larvae are directed upwards, and these, when hatched, push 

 their way out either through the spongy material, and so up to the entrance of the cavity or dii'ectly 

 through the ground. 



The British species of this family, although they are able to make the fields vocal during the 

 summer, are not very numerous, nor are they of very large size. On the continent of Europe, 

 however, even in the latitude of England, several larger species occur, and in warmer regions we find 

 quite gigantic forms, some of the Brazilian Acridia reaching seven or eight inches in expanse of wing 

 The species, whose ravages have given the name of Locust an unenviable notoriety, are not, however, of 



FEMALE LOCUST DEPOS1TIXG EGGS. 

 {After Bulletin of U.S. Entomological Com- 

 mission.) 



