216 MEANS OF DEFENCE OF INSECTS. 



I. The principal passive means of defence vvitli which 

 insects are provided, are derived from their colour and 

 form, by which they either deceive, dazzle, alarm, or an- 

 noy their enemies; or from their substance, involuntary 

 secretions, vitality, and numbers. 



They often deceive them by imitating various sub- 

 stances. Sometimes they so exacdy resemble the soil 

 which they inhabit, that it must be a piactised eye which 

 can distinguish them from it. Thus, one of our scarcest 

 British weevils {CurcuUo nebulosus), by its gray colour 

 spotted with black, so closely imitates the soil consisting 

 of white sand mixed with black earth, on which 1 have 

 always found it, that its chance of escape, even though 

 it be hunted for by the lyncean eye of an entomologist, 

 is not small. Another insect of the same tribe [Thylu- 

 citcs scabriculus), of which I have observed several species 

 of ground-beetles, {Harpohis, &c.) make great havoc, 

 abounds in pits of a loamy soil of the same colour pre- 

 cisely with itself; a circumstance that doubtless occasions 

 many to escape from their pitiless foes. — Several other 

 weevils, for instance Chlorima ?iivea and cretacea, resem- 

 ble chalk, and perhaps inhabit a chalky or white soil. 



Many insects also arc like pebbles and stones, both 

 rough and polished, and of various colours ; but since 

 this resemblance sometimes results from their attitudes, 

 I shall enlarge upon it under my second head: whetlier, 

 however, it be merely }iassive, or combined with action, 

 we may safely regard it as given to enable them to elude 

 the vigilance of their enemies. 



A numerous host of our litde animals escape from 

 birds and other assailants by imitating the colour of the 

 plants, or parts of them, \\ hich lliey inhabit; or the twigs 



