108 ORTIIOPTERA. 



is not strong, so that the four parts may be readily sep- 

 arated. The abdomen also bears two caudal setae {se). 



The mole-cricket {Gryllotalpa boi-ealis) offers a 

 most instructive example of the effects of the habit 

 of burrowing upon structure. The search for food, 

 such as the roots of plants, worms, and grubs, and the 

 habit of living in the earth, has led this animal to 

 excavate sul^terranean galleries ; and in so doing it 

 has modified the structure of its fore limbs till they 

 have become stout, strong, and efficient digging im- 

 plements. A similar adaptation is seen among Ver- 

 tebrates in the foot of the common mole, the animal 

 whose name has been given to the insect. Living 

 underground, the mole-cricket has no need of leaping- 

 legs, and therefore the third pair of legs are not 

 greatly enlarged. 



LOCUSTID.^. 



The characteristics of these insects have been briefly 

 stated on p. 9. 



After the structure and habits of the locust become 

 familiar to pupils, a very instructive lesson may be 

 given on the meadow grasshopper, Orchelimum vid- 

 gare (PL IV., Fig. c^g $ ; Fig. 6o9 ). This grasshop- 

 per lives among the grass and green plants of moist 

 fields and meadows, and its near relatives, the katy- 

 dids,^ among the leaves of shrubs and trees. The col- 

 oration of each species is admirably adapted to its 

 habitat, the grasshopper and katydid being surrounded 

 by foliage, and on green stems are a lively green ; 



1 For figures and descriptions of different species of katydids, 

 see Riley, Sixf/i Report N'oxiotis and Beneficial Insects of Mis- 

 souri, 1874, pp. 150-169. 



