April 1904] 



KNOWLEDGE & SCIENTIFIC NEWS. 



53 



Kallima niachfs. India. Two Specinjens at rest among leaves. 



or grey colouring. Moreover, this deception is materially 

 heightened by the unique attitude of repose obtaining 

 among these caterpillars, which differ from most lepidop- 

 terous larva; in possessing only two instead of five pairs 

 of pro-legs. These are placed at the extreme posterior 



riul 111 the body, while the three pairs of true legs at the 

 other extremity arc usually exceedingly diniinuti\e. 'l"he 

 perfect stick-likeness is gained in the following manner. 

 The caterpillars of the GconulridfC usually feed at night. 

 When daylight comes, or under Ihe stimulus of alarm, 

 they take a tirm hold upon ilic iwig with their four pro- 

 legs and stretch out their cylindrit al body stiff and 

 straight at an acute angle. In this position they are 

 capable of remaining, absolutely motionless, for liours 

 together. But to counteract the terrible strain which the 

 attitude would impose u])()ii the body of the caterpillar, 

 each usually spins a strong, though practically invisible 

 silken thread from its mouth to the twig fin which it rests. 

 A family of insects remarkable above all otliers for the 

 almost universal protective resemblance of its members 

 is the Phasmida. In order to understand these creatures, 

 which are numerous in all tropical countries, it is neces- 

 sary to know something of their habits, llnlike their 



Three Caterpillars ol Hemerophila abruptaria. l-.iifilaml 



ClitumnuA Sundaicus. Stick-hke I'h.isiiiiil, 



near relatives, the Mantidce or " praying insects," which 

 are voracious insect eaters, the Phasmida' are exclusive 

 vegetarians, feeding greedily upon the leaves of the plants 

 which form their resting places. In movement, Phasmids 

 are extremely sluggish, and many of the species — being 

 apterous or possessing, at most, only rudimentary wings — 

 are incapable of flight. Thus, they are much exposed to 

 the attacks of birds and other insectivorous creatures — 

 have been so, in all probability, forages past. This per- 

 secution might be supposed to foster any variation in 

 shape or colour likely to be of protective value. And, as 

 a matter of fact, the whole of the Phasmidce, almost with- 

 out exception, have undergone striking modifications in 

 the direction of special resemblance. 



As a rule, the bodies of these insects have become 

 greatly lengthened, while the legs are long and slender. 

 Those known popularly as " walking sticks," of which 

 the Cliluinnus sundaicus shown in the accompanying photo- 



