58 MIMICRY, AND OTHER PROTECTIVE 



dung. Kirby and Spence mention the small beetle 

 Onthophilus sulcatus as being like the seed of an um- 

 belliferous plant ; and another small weevil, which is 

 much persecuted by predatory beetles of the genus 

 Harpalus, is of the exact colour of loamy soil, and 

 was found to be particularly abundant in loam pits. 

 Mr. Bates mentions a small beetle (Chlamys pilula) 

 which was ^indistinguishable by the eye from the 

 dung of caterpillars, while some of the Cassidse, from 

 their hemispherical forms and pearly gold colour, re- 

 semble glittering dew-drops upon the leaves. 



A number of our small brown and speckled weevils 

 at the approach of any object roll off the leaf they 

 are sitting on, at the same time drawing in their legs 

 and antennae, which fit so perfectly into cavities for 

 their reception that the insect becomes a mere oval 

 brownish lump, which it is hopeless to look for among 

 the similarly coloured little stones and earth pellets 

 among which it lies motionless. 



The distribution of colour in butterflies and moths 

 respectively is very instructive from this point of 

 view'. The former have all their brilliant colouring on 

 the upper surface of all four wings, while the under 

 surface is almost always soberly coloured, and often 

 very dark and obscure. The moths on the contrary 

 have generally their chief colour on the hind wings 

 only, the upper wings being of dull, sombre, and often 

 imitative tints, and these generally conceal the hind 

 wings when the insects are in repose. This arrange- 

 ment of the colours is therefore eminently protective, 



