2 90 ORTHOPTERA chap. 



is the perfect Insect, with the alar organs free and large, the 

 prothorax much changed in form, the colour different. From the 

 above it will be seen that the chief changes occurred at the third 

 and fifth ecdyses, after each of which a considerable difference in the 

 form of the Insect was revealed. In the first three instars the 

 sexes can scarcely be distinguished, in the fourth they are quite 

 distinct, and in the fifth coupling is possible, though usually it 

 does not occur till the final stage is attained. 



The discovery that Orthoptera change their colours in the 

 course of their development, and even after they have become 

 adult, is important, not only from a physiological point of view, 

 but because it throws some light on the questions as to the 

 number of species and the geographical distribution of the 

 migratory locusts, as to which there has existed a great confusion. 



The Acridiidae are considered to be exclusively vegetable 

 feeders, each individual consuming a very large quantity of food. 

 The mode in which the female deposits her eggs has been 

 described by Eiley,-^ and is now widely known, his figures having 

 been frequently reproduced. The female has no elongate ovi- 

 positor, but possesses instead some hard gonapophyses suitable for 

 digging purposes ; with these she excavates a hole in the ground, 

 and then deposits the eggs, together with a quantity of fluid, in 

 the hole. She prefers hard and compact soil to that which is 

 loose, and when the operation is completed but little trace is left 

 of it. The fluid deposited with the eggs hardens and forms a 

 protection to them, corresponding to the more definite capsules of 

 the cursorial Orthoptera. 



The details of the process of oviposition and of the escape of 

 the young from their imprisonment are of much interest. Accord- 

 ing to Klinckel d'Herculais ^ the young Stcmronotus maroccanus 

 escapes from the capsule by putting into action an ampulla 

 formed by the membrane betw^een the head and the thorax ; this 

 ampulla is supposed to be dilated by fluid from the body cavity, 

 and is maintained in the swollen condition by the Insect accumu- 

 lating air in the crop beneath it. In order to dislodge the lid of 

 the capsule, six or seven of the young ones inside combine their 

 efforts to push it off by means of their ampullae. The ampulla 



^ Rep. Ins. Missouri, ix. 1877, p. 86. 



^ Bull. Soc. ent. France (6), x. 1890, p. xxxvii,, and CE. Ac. Paris, ex. 1890, 

 p. 657. 



I 



