188 HOUSE, GARDEN, AND FIELD 



All leaping insects do not adopt the method of the 

 cricket ; the click beetles, lying on their backs, first arch 

 the body, and then suddenly reverse the curve, so that 

 the elytra strike the ground with a smart blow ; the spring- 

 tails leap by straightening a forked tail, which was pre- 

 viously bent forwards beneath the body, and in many cases 

 secured with a catch ; the cheese-hopper (larva of the 

 cheese-fly) grasps the end of its body with a pair of strong 

 hqoks borne on the head, and having thus bent itself 

 double, suddenly lets go, and forcibly straightens the 

 body (see p. 114). Hardly any order of insects can be 

 mentioned which does not include some that leap either 

 as larvae or adults. The Mexican jumping bean is well 

 known to owe its amusing movements to the activity of a 

 caterpillar. 1 



The mouth-parts of the cricket are so like those of the 

 cockroach that anybody who knows the one can easily 

 understand the other. There is indeed a striking uni- 

 formity of mouth-parts throughout the Orthoptera 

 striking because the common plan is by no means a simple 

 one, but an aggregate of many parts, each prone to assume 

 special adaptations. 



If we take a fresh cockroach and strip off the labium, 

 which forms the floor of the mouth, we shall find on its 

 surface a tongue-like projection, which is very likely used 

 somewhat like the human tongue, to mix up and moisten 

 the particles of food. Beneath this tongue is the large 

 single opening of the salivary duct, which, when followed, 

 can be seen to divide into the two ducts of the salivary 

 glands. The microscope shows that the salivary ducts of 

 the cockroach have a ringed appearance, like the air- tubes 

 of an insect. Stiff threads, which branch frequently, are 

 wound about them, and keep them from collapsing, acting 

 indeed just like the spiral threads of an air- tube, which 

 they closely resemble. A tongue and a salivary duct are 



1 The caterpillar is that of a small moth (Graptolitha sebastianse) ; the 

 "bean" is the fruit of a spurge (Sebastiana). 



