ORTHOPTERA. 



671 



side and the coxae of the legs are attached to the sides of the thorax, not 

 to the ventral surface. Eight distinct segments can be counted in the 

 abdomen, and behind the last are the organs connected with reproduction. 

 The tegmina are long and narrow ; the hind-wings fold up like a fan and 

 are covered by the tegmina. The hind legs are often very long and 

 powerful and are used for jumping. The well-known noise made by 

 grasshoppers is produced by rubbing a row of minute prominences on the 

 inner surface of the femur of the last legs against certain projecting veins 

 on the outer side of the tegmina. This sound-producing apparatus is 

 better developed in the males than in the females, the last named sex 

 rarely producing sounds audible to our ears. The auditory organs are 

 one on either side of the first abdominal segment ; each consists of a 

 membrane surrounded by a complex rim and well supplied with 

 nerves, muscles and tracheae,. It is well developed in both sexes. This 

 family is remarkable amongst the Orthoptera for possessing spacious 

 vesicles connected with the tracheae, and when these are fully inflated 

 they doubtless serve to lighten the body of the insect during its flights 

 (Fig. 386). The female prepares by means of certain gonapophyses a 

 hole in the earth in which she deposits her eggs and a quantity of a 

 fluid which hardens around them. In this way Caloptenus spretus 

 lays about 100 eggs, in four batches of about twenty-five. The young 

 moult soon after leaving the egg and the last stage, the sixth, is the adult. 

 During the post-embryonic development there is a considerable change 

 of colour as well as an increase in the complexity of parts. The Acridiidae 

 are vegetable eaters, and include most of those insects popularly known as 

 " locusts " which at times do incalculable harm to the plant-world. When 

 for some unknown reason species of this family increase at a prodigious rate, 

 and above all when, as is the case with many species, they develop migratory 

 habits, the vegetation of whole regions may be destroyed. During a 

 single season in the island of Cyprus over 1,300 tons of *' locust " egg- 

 cases have been destroyed and this figure gives some slight idea of the 

 gravity of the plague. The swarms do not necessarily occur every year, 

 in fact there is as a rule some interval between each attack. The pre- 

 disposing cause is unknown. One of the most important migratory species, 

 Pachytylus cinerascens (Fig. 422), is indigenous to Belgium but gives rise 

 to no swarms in that country. The direction of the locust flight seems to 

 depend largely on the wind, and the insects are said to fly at great heights. 

 The migratory instinct is not confined to the winged adult ; the wingless 

 young sometimes jump 

 through the land in count- 

 less hordes clearing off every 

 blade of grass as they pro- 

 gress, and doing perhaps 

 more damage than the 

 winged adults. 



In the Old World, especi- 

 ally in the East, the most 

 abundant " locust " is Pachy- 

 tylus cinerascens, which when 

 dermrWl nf it winox nH Fl0 ' 422. European migratory locust, Pachytylus 



cinerascens ?. From Sharp, 

 legs and fried in butter tastes 



not unlike shrimps and is eaten by the inhabitants of Palestine. P. migra- 

 torius is rather more restricted in range, being limited to E. Europe 



