264 INSECTS AND MAN 



colony. They are provided with relatively enormous man- 

 dibles, set on substantial heads. Should the wall of a 

 termite nest be broken, the soldiers at once run to guard 

 the breach, threatening with their mandibles any and 

 every one who approaches. This defensive attitude they 

 maintain till the workers have repaired the damage. In 

 dealing with termites as household insects, we are but 

 little concerned with their nests, which are exceedingly 

 varied in size and form ; some are mere labyrinths of 

 galleries tunnelled out in the ground, others are huge 

 mounds which may reach a height of twenty feet. 



CRICKETS AND EARWIGS 



Of the other British household insects, the majority are 

 so common that they need little more than passing notice. 

 Besides the cockroach, the order Orthoptera is represented 

 in our houses by the cricket and the earwig. The house- 

 cricket, Gryllus domesticus, is the only member of the 

 family Gryllidce that has assumed domestic habits. Chest- 

 nut brown in colour, winged in both sexes, and provided 

 with well-developed hind legs, the house cricket bears 

 considerable resemblance to a brown grasshopper. The 

 wings are worthy of study for they are sound organs, 

 serving the same purpose as the sound organs of the 

 periodical cicada, though totally different in structure and 

 action. The lower membranous wings are similar in both 

 sexes and have veins radiating from the base, so that 

 they can be folded fan-wise, hence the name Orthoptera 

 or straight wings ; the upper, more rigid wings of the male, 

 however, are peculiar. On the portion of the wing that 

 lies flat on the insect's back, as opposed to the portions 

 that lie against its sides, there are strongly veined areas 

 and also clear ones ; by the former the sound is produced, 

 by the latter it is intensified. When about to make its 

 well-known chirp, the male cricket depresses its abdomen 



