324 



ORTHOPTERA 



CHAP. 



I 



apparently in making use, not of a general inspection, but of a 

 scrutiny of the outlines of the leaves and twigs of a tree. By 

 this means, when the eye is accustomed to the task, the Insects 

 can 1)6 detected with comparative ease ; much in the same way, 



M. Boutan says, as a figure, placed 

 in an engraving in such a way as to 

 elude the eye, is appreciated with ease 

 after the eye has once perceived it. 



Some of the Locustidae are pro- 

 vided with means of defence of a posi- 

 tive nature. The Algerian Eugaster 

 guyoni ejects two jets of a caustic 

 orange-coloured fluid from two pores 

 situate on the sides of the meso- 

 sternum, and covered by the anterior 

 coxae. This species is carnivorous as 

 well as herbivorous, and produces a 



sound more like humming than stridu- 

 lation.^ 



We have previously j)ointed out 

 that some of the Acridiidae resemble 

 the stick - Insects rather than the 

 members of their own group ; and 

 similar cases occur amongst the Locus- 

 tidae. Such a resemblance has, how- 

 ever, only been found in a few species 

 of the tribe Prochilides. We figure 

 one of these, Fhasmodes ranatriformis, 

 a native of South - AVest Australia. 

 The very elongate linear form and the 

 total absence of alar organs give this 

 Insect a considerable resemblance to 

 the stick -Insects or apterous Phas- 

 midae. Frochilus australis is allied 

 to this curious Locustid, but the alar organs are present in both 

 sexes, and the Insect bears a great resemblance to the winged 

 Phasmidae. This is due not only to the general form and colour, 

 but also to the fact that the tegmina are very narrow, which 



1 Bonnet anil Finot, Rev. Sci. Nat. (3) iv. p. 345. The word we have translated 

 as hnmmine is ' bruissement." 



Fig. 200. Phasniodes ranatri- 

 formis, iQVLi?i\e. Australia. (After 

 Westwood. ) 



