MIMICRY. 459 



they wings to escape by flying, and generally go in large bodies 

 easily found and approached." Mr. Belt, however, concludes 

 that the Spider is thus protected against the attacks of small 

 insectivorous birds.* Subsequently, however, Mr. Herbert H. 

 Smith has reaffirmed what Mr. Belt denied — " the Spiders eat 

 the Ants," and "they eat the particular Ants which they mimic. 

 At all events, we verify this fact in a great number of cases, and 

 we never find the Spiders eating any but the mimicked species." f 

 Dr. Scharff thinks "that the colours of Slugs in Ireland are at 

 all ages, as a rule, protective" ;% while Mr. Adams is inclined to 

 think " that climate may be a factor in the matter." He has 

 " taken more brilliant forms, and those more abundantly in the 

 South of England (ivhere the climate is warmer), than in the 

 North." Again, " all along the south coasts of England and 

 Wales, Cardigan Bay, and the west coast of the Isle of Man, and 

 the north coast of Ireland (all of ivhich are noted for a mild 

 climate), I have taken coloured forms abundantly ; while on the 

 coasts of Lancashire and North Wales, and the east coast of 

 England from the Thames to the Tees (where the climate is 

 more bracing), I have no personal records for anything but the 

 type."§ 



In plant-life such resemblances are not uncommon. In para- 

 sitic fungi " the fructification of Polyporus betidinus strongly 

 resembles the whitish bark of the birch, and that of P.fomen- 

 tarius, parasitic on old beech trees, exhibits the same pale grey 

 as does the trunk of a beech." There is a butterfly common in 

 certain parts of the Argentine which Dr. Seitz at first mistook for 

 the European Vanessa (Araschnia) levana 9 so closely does it 

 resemble that butterfly in colour, in the notching of the wings, 



* ' The Naturalist in Nicaragua,' pp. 314-5. 



f ' Brazil, the Amazons, and the Coast,' p. 223. 



J ' Slugs of Ireland,' p. 554. 



§ ' Coll. Man. Brit. Land and Freshwater Shells,' 2nd edit. p. 23. 



|| Kerner and Oliver, ' Nat. Hist Plants,' vol. i. p. 166. 



The genus Volucella comprise large flies which mimic Humble-Bees in 

 colour and form. As observed by Mr. Pocock : " It was long supposed that 

 the females were thus enabled with impunity to enter the nests of Humble- 

 Bees, and lay their eggs amongst those of the proper owners." But these 

 mimics of Humble-Bees also "visit for the same purpose the nests of Wasps, 

 to which the flies bear no particular resemblance." 



