I02 YORKSHIRE NATURALISTS' UNION. 



species of different form and shape, and the larva only pro- 

 truding- the head and jaws for purposes of feeding-. The various 

 species of Tinea feed on our furs, hair cushions, wool, clothes, 

 etc., the large g^roup of Elachista nearly all mine the various 

 species of grasses and rushes ; LitlwcolletidcB and Nepticiilce 

 find their entire world often beneath the cuticle of a single leaf, 

 the former genus makings unsightly brown blotches on the 

 leaves, the latter long- tortuous mines ; they are so minute too, 

 that as the late Mr. Stainton said "a nut leaf containing from 

 twenty to thirty larvae of Nepticiila niicrotheriella is no unusual 

 sig^ht." 



But it is in the larvae of the great g-roup of the Geometrae 

 that such intense interest has centred with so many of us of 

 late years. A¥ith a very few exceptions the larva; of the group 

 feed quite exposed, consequently have to rely on their colour 

 and attitude for protection agfainst enemies. Hence they have, 

 far more than those of any other group, provided evidences of 

 mimicry ; and the diversity of their ways, together with their 

 perfect assimilation in appearance to their food plants is 

 marvellous. Examine the larvae of the extensive family of the 

 EiipithecicB or ' Pugs ' as we familiarly call them. Exclusive 

 in their habits, each species, speaking- generally, confining- 

 itself to one plant, and then often to the flowers or seeds only, 

 some of them having- towards a dozen different varieties ; and 

 yet although we may know there are nvimbers of them feeding 

 on a flower head, how very few we can see. Half a dozen 

 varieties, totally different in colour, for the flower feeders are 

 generally of several colours, though the pattern is usually the 

 same, but all equally inconspicuous on the flower. Tap the 

 plant sharply over a net or inverted umbrella, and they fall into 

 it in numbers, and are then striking and conspicuous enough. 

 On the flower head, the green forms were resting- on the green 

 under parts, the yellow with red or purple lozenge-shaped 

 marks, among- the fresh, brig-ht, or partially withered flowers 

 as the case may be ; the varieties of different shades of brown 

 among- the unripe, or further advanced seeds, etc. This of 

 course is in the daytime, when the larvae are usually at rest and 

 absolutely quiet ; at night they might all be seen with the aid of 

 a lamp, feeding on the flowers, and lively enough, but at that 

 time there are no birds on the look-out for them, and they are 

 comparatively out of danger. The pretty caterpillar of 

 Ejipithecia nanata, the ' Pug ' we are so familiar with on our 

 Yorkshire heaths, is a good example ; it has t\vo very distinct 

 forms, the more nvu-nerous being bright pinkish-purple and 

 white, exactly like the ling flowers on which it feeds ; the other 

 green and white, assimilating just as closely with the leaves. 

 But the most striking example I know among the EiipithecicB is 

 in the case of the very local Eupithecia extensaria, which is 

 only known in Britain as occurring on a small area on the 

 Norfolk coast, near Hunstanton. It feeds on the Arte?nisia 



