210 



KNOWLEDGE & SCIENTIFIC. NEWS. 



[Sept., 1904. 



insects resembls more or less closely those objects by 

 which they are habitually surrounded — the protection 

 becoming more certain in proportion to the completeness 

 of the likeness. But with warning colours, exactly the 

 reverse is ^the case. Insects assignable to this class are 

 not coloured to be hidden, but in order that they may 

 readily be seen. 



It is believed — and in many instances this is definitely 

 known to be the case — that such conspicuously coloured 

 insects possess some hurtful (|uality which renders them 

 inedible, and that their showy livery acts as a warning 

 to insectivorous creatures in general. The reason why 

 warning colours are thought to benefit a species is 

 explained in the following manner. Insects are, for the 

 most part, very frail creatures, and one peck from a bird 

 bent upon testing the edibility of (say) a caterpillar, 

 would, in all probability, result in the creature's death. 

 Thus, the mere fact of its being unsuitable for food 

 would be of no avail in savins; its life. But if the cater- 



I— i/.;.i.inia ,h„rith„,:vi. 2—HeluuJ,ifi,iu,iina. Ex Trop. South America. 

 The Heliconiida; have all dark brown or black wings, lined or 

 spotted with very brilliant colours. 



pillar were coloured in a manner sufficiently striking to 

 become impressed upon the mind of the bird, a distinct 

 advantage to the species might be expected to result. 

 For the bird, presuming it to be capable of learning a 

 lesson, would give up " experimental tasting " in so far 

 as insects coloured in a similar manner were concerned. 

 As an example of a warning colour combination by 

 no means uncommon in the insect world, the caterpillar 

 of the Cinabar moth [Euchclia jacobacT) which is zebra 

 striped in alternate bands of black and yellow, may be 

 cited. This larva has been proved to be nauseous in 

 taste, and to be rarely eaten by birds or other insecti- 

 vorous creatures old enough to have gained experience 

 in " the ways of the world." The same yellow and 

 black striping is to be seen upon the bodies of many 

 species of wasps and bees— insects which would prove 

 very unsatisfactory eating on account of their poisonous 

 stings. 



The theory of warning coloration was first suggested 

 by Dr. A. R. Wallace to account for the extremely 

 bright colours exhibited by certain caterpillars. It has 

 since been applied to whole tribes of insects, of all 

 orders ; and so strong is the evidence in its fa\-our— the 

 result of systematic experiments conducted in various 

 latitudes with birds, lizards, and other insect-eating 



creatures — that what was originally a theory may now 

 fairly be regarded as a well-established fact. Indeed, so 

 distinct are the colours and colour combinations possessed 

 by inedible species, and so unlike are they to the colours 

 of insects which do not possess noxious qualities, that 

 the student is frequently able to tell at a glance whether 

 a given species is an example of warning coloration or 

 not, even though he may never before have seen it. 



Amongst butterflies, the examples of warning liveries 

 are particularly striking. 



.Icrat'd sp. Ex Sierra Leone (fore wings sooty, black spots; hind wings 

 brick red, black spots .) 



In South America, the "protected" species — as those 

 which possess some noxious quality are usually termed — 

 are exceedingly numerous, and are well typified by such 

 genera as MdJwma, Mclinca, and Hcliconiiis. These 

 butterflies are rendered inedible by the acrid or evil- 

 smelling juices contained in their bodies. Even in the 

 case of long-dead specimens which have been temporarily 



Aiii'iini^i ochl<a. Ex 5outh Africa iblackish = brown, with white areas}, 



relaxed for setting, the unpleasant odour of these juices 

 is very apparent, resembling the scent which is left upon 

 the fingers after handling a ladybird beetle. Such 

 butterflies, in common with other evil-tasting species in 

 other parts of the world, are slow and measured in their 

 flight, fluttering in an unconcerned manner from flower 

 to flower as though experience had taught them that 

 they have little to fear from birds, reptiles, monkeys and 

 other enemies to insect life. 



Although the species of warningly coloured butterflies 

 are exceedingly numerous in the New World, tliey arc 



