32 2 Insects and their Surroundings 



ing closely resemble wasps. Drone-flies (Eristalis) bear 

 much resemblance to bees. Such likeness is known as 

 " mimicry," and it is believed that the moths and flies 

 secure immunity from attack through being mistaken for 

 the stinging insects. In the same way tropical butter- 

 flies of the sub-families believed to be noxious — the 

 Danainse, Heliconiinae, and Acrjeinge — are "mimicked" 

 by butterflies of other groups. In South America 

 many species of Pieridae are found whose wing- 

 patterns, quite unlike those usually characteristic of 

 their family, show staring contrasts of yellow, black, 

 and red, in close imitation of various species of Heli- 

 coniinae. A very common North American Danaine 

 butterfly — ^nosia erippus — whose wings are tawny 

 brown with black veins and margins, is closely 

 mimicked by a Nymphaline, Limenitis mis'ippus, which 

 belongs to the same genus as our graceful and 

 delicately tinted "White Admiral." In some cases 

 the female of a species is a "mimic" while the male 

 retains the normal livery of his group. There are two 

 Indian Nymphaline butterflies, HypoUmnas holina and 

 H. misipptis, whose males are similar to each other, 

 both having black wings with central white violet- 

 tinted spots. The female of H. bolitm has blackish 

 wings with whitish marginal spots and is an imperfect 

 mimic of the common Danaine butterfly, Etiploea core. 

 The female of H. misippus, altogether unlike her 

 mate, has tawny brown wings, the fore-wings with a 

 white apical patch ; she is an extremely perfect mimic 

 of another common Danaine, Limtias chrysippus. Such 

 strongly marked divergence between the two sexes of 

 a species is surprising, but the varieties of H. holina 

 go far to bridge over the gap, the females showing 

 the gradual growth of the tawny colour from a small 

 basal spot to a large suffusion of the wing-area. It is 

 hard to suggest what first led to the development of 



