BODILY CHARACTERISTICS— INCONSPICUOUSNESS 



297 



stages of their existence. Among our native Moths, for instance, 

 there is one group (Geometers) containing over 200 species, in 

 which the succulent caterpillars move along in a curious way 

 which has earned for them the name of Loopers, and is also 

 the origin of the name of the group. The front part of the 

 body bears three pairs of jointed legs corresponding to those 

 of the future moth, while at the hinder-end are two pairs of 

 sucker-like pro-legs. It is by alternate use of these fore and aft 

 groups of limbs that the characteristic movements are effected. 

 But the larvje in question have also earned the name of Stick- 

 Caterpillars, from the very perfect way in which they simulate 

 resemblance to the twigs of plants on which they live. Holding 

 on firmly by means of its pro -legs, and extending the body 

 obliquely outwards, such a caterpillar remains motionless and 

 rigid for hours, until the cravings of hunger render it necessary 

 to crawl away and take the next meal. Such a severe trial of 

 patience and muscular power are rendered rather less trying 

 by a silken thread attaching the head to a neighbouring twig. 

 A Stick-Caterpillar in the motionless condition harmonizes so 

 perfectly with its surroundings, both as regards shape and colour, 



that it can only be detected by an 

 unusually keen or practised observer. 

 Poulton (in The 

 Colottrs of Ani- 

 mals) describes 

 as follows one of 

 the most remark- 

 able cases: — " I 

 will illustrate the 

 extraordinary de- 

 gree of resem- 

 blance attained 

 in Geometrce by 

 a description of 

 the larva of one ^'* 

 ofour most abun- 

 dant species, the Brimstone Moth {Ritmia cratcsgatd). The appear- 

 ance of the larva when seated among the twigs of its commonest 

 food-plant — hawthorn— is shown in fig. 481- It will be observed 

 that some of the twigs are slightly bent in the middle, and that 



Fig. 481.— Caterpillars of Rrimstone Moih 

 [Rumia cratisgata), in protective attitudes 



,82.— Hinder End of Caterpillar of 

 Brimstone Moth (magnified) 



