1887.] VALUE OF COLOUR AND MARKINGS IN INSECTS. 239 



can adequately appreciate the meaning of the colours and markings 

 of any animal. 



III. Insects which evade their Enemies. 



We now come to Wallace's converse suggestion — that just as 

 conspicuous forms which court observation will be avoided, so 

 the insects which harmonize with their surroundings, and which 

 evade their enemies, will be greedily eaten when detected and 

 caught. I have adopted Meldola's suggestion that the terms 

 " protective resemblance " should be applied to the appearances 

 which tend to deceive enemies by their resemblance to motionless 

 (vegetal or mineral) surroundings, the term "mimicry" denoting the 

 resemblance to other animals. On entering upon the experimental 

 investigation, I thought that I should have little to record except a 

 complete agreement with everything which has been previously said 

 upon the subject. I was surprised, however, to find some instances 

 which are entirely antagonistic to the principles laid down by 

 Wallace. Unfortunately the instances recorded by other observers 

 are exceedingly few. Jenner Weir evidently experimented with a 

 large number of species, but he gives very few details, and for the 

 most part is content with summing-up his results as favourable, 

 without exception, to Wallace's suggestion, in these words : — " I will 

 now add a few words on those larvae which are eaten greedily by 

 birds, and my remarks on the subject will be brief; it will be 

 unnecessary to detail all the experiments made, as the results are 

 easily generalized. 



" All caterpillars whose habits are nocturnal, dull-coloured, with 

 fleshy bodies and smooth skins, are eaten with the greatest avidity. 



" Every species of green caterpillar is also much relished. 



" All Geometrse, whose larvae resemble twigs as they stand out 



from the plant on their anal prolegs, are invariably eaten 



They eat with great relish all smooth-skinned larvae of a green or 

 dull-brown colour, which are nearly always nocturnal in their habits, 

 or mimic the colour or appearance of the plant 'they frequent." 



Jenner Weir, however, gives details of experiments with other 

 stages of Lepidoptera ; and I am now able to add many valuable 

 details from his experiments upon Lizards in 1886. There are also 

 a few instances to include from Mr. Butler's paper (already quoted) 

 and a few of which I have heard from him by letter. In my experi- 

 ments I chiefly made use of the imagos of Lepidoptera, as I nearly 

 always sought for conspicuous larvae with which to test the sug- 

 gestion previously discussed. 



Other observers having given so little detail, it follows that Wal- 

 lace's converse suggestion possesses extremely little precisely recorded 

 experimental foundation. There is, however, no reason to doubt 

 that Jenner Weir's conclusions will be very generally confirmed by 

 extended experiments, and they doubtless express the results of 

 many observations. But as I have come across a few startling 

 exceptions among the most protectiA'ely coloured forms, it is safer not 



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