674 



CLASS IV. INSECTA. 



Both in the ovipositor 

 and in the position of the 

 auditory and phonetic or- 

 gans the Gryllidae or 

 Crickets come close to the 

 Locustidae, the chief 

 divergences between the 

 families resting in the 

 arrangements of the teg- 

 mina, the usual number 

 of the tarsal joints and the 

 development of the un- 

 jointed cerci anales. The 

 shrill note of the Gryllidae 

 is caused by the rapid 

 vibration of the tegmina, 

 " the edge of one acting 

 on the file of the other." 

 The hind wings are usually 

 longer than the tegmina 

 and often than the body. In the abdomen the pleura are markedly large 

 and the abdominal stigmata correspondingly conspicuous. Crickets have 

 but little beauty of shape, colour or voice. They seldom leave the 

 ground, though the tree-crickets climb on to plants ; with the exception 

 of the Gryllotalpinae they are herbivorous, and are very cosmopolitan 

 in their distribution. 



The Gryllidae are divided into seven sub-families : 



1. Tridactylinae. This sub-family departs from the usual rule in- 

 asmuch as its antennae are short, of some ten joints, and there is 

 no ovipositor. Their wings also differ from those of other Gryllidae, 

 and they have no auditory organ on the legs. On the whole their 

 affinities are doubtful. Tridactylus South European ; Rhipipteryx 

 South American. 



2. Gryllotalpinae. Gryllolalpa (mole-crickets) burrows underground 

 by means of stout fore-legs, which by a shear-like action cut through 

 roots, and thus causes some damage to crops. It is largely carnivorous. 

 Gfvulgaris, now becoming rare in England, lays 200-400 eggs over 



FIG. 4.21.Gryllus campestris 



FIG. 425. Cryllotalpa vulgaris. 



which the mother watches carefully. These hatch in a month and 

 the female feeds the larvae until they undergo their first moult ; on 

 the other hand the male occasionally devours them. Cylindrodes is 

 an Australian genus, very destructive to plants. 



3. Myrmecophilinae. Myrmecophila. 



4. Gryllinae. Gryllus campestris is the field cricket, G. (Acheta) 



