PROTECTIVE COLORATION AND DEFENSIVE STRUCTURES OF LARVAE. 79 



brown hue. The larva also becomes stout, and comparatively short, 

 and its resemblance at this stage to the catkins of the birch is very 

 striking, the green larva? resembling the younger, the brown larvae tbe 

 older, Catkins. Harwood says tbat the brown larvae mature later, and 

 that the larvae found on hazel are somewhat different in appearance 

 from those found on birch. 



Equally peculiar as to the change of colour, only in this case the 

 change accompanies a change of habit, is that of the larva of Emme- 

 lesia unifasciata, which feeds within the seed-pocls of Bartsia odontites 

 when young and the pods are green, and is itself, at that stage, of a 

 green tint, corresponding with that of the seed-pods. It, however, 

 changes its habit by feeding outside, when almost mature, and con- 

 temporaneously with its last change of skin, it changes its tint and 

 ornamentation. 



Miss Gould says that the resemblance of the larva of Rumia lutcolata, 

 in shape as well as in colour, is extremely protective, the angular 

 attitude of the larva at rest, rendering it almost indistinguishable from 

 the twig. In the case of larvae with green surroundings, this likeness 

 is greatly heightened by the touches of red, which exactly match the 

 thorns and one side of the stem of the young hawthorn shoot. 

 Poulton also, referring to this species, says that the resemblance of the 

 larva to a twig of its food-plant is most striking, for the dorsal tubercles 

 which are to be found near the middle of the larva represent very 

 faithfully a superficially similar structure upon many side twigs of 

 the food-plant, and, he further notices, that not only do these pro- 

 jections occur towards the middle of the length of the twigs, but they 

 are situated on the angle of a slight bend, a character which is also 

 produced in the larval form. He further points out that the different 

 forms of the larvae are coloured in almost the same manner as the 

 varying tints of the hawthorn twigs. He considers that the remarkable 

 specialisation of the form and colours of certain larvae to a special 

 food-plant, gives a strong clue to the ancestral food-plant of a species, 

 whose larva now feeds on more than one plant. 



Barrett notes the resemblance that the larva of Eupitliecia extensaria 

 bears to its food-plant, Artemisia maritima, and says : The stems and 

 leaf -stalks of the plant are furrowed and clothed with white down, in 

 such a manner that all appear striped, with alternate green and dull 

 white, and this larva is similarly ornamented with longitudinal stripes 

 of the same colours and of the same width ; the young flower-buds of 

 the plant are tipped with brown, and the front of the head of the larva 

 is coloured in the same manner ; the segments of the leaves are some- 

 what tumid at the tips, and the anal legs or claspers of the larva are 

 swollen or rounded into precisely the same shape. This last adaptation 

 would appear superfluous, if it were not for a curious trick which the 

 larva has, at times, of raising its posterior end stiffly out while holding 

 on by its thoracic legs — thus apparently standing on its head. 



The special resemblance that the full-grown larva of Hybocampa 

 milhauseri bears to a curled oak-leaf, partly eaten and abandoned by a 

 Tortrix (viridana ?) larva has been well described (Entom., xxiii., p. 92) 

 by Chapman. He says : By chance 1 one day brought in with the 

 food for some larvae of this species, so exact a resemblance of the full- 

 grown larva, that there could not be any doubt as to the meaning of 

 all its curious outlines and markings. This was a curled oak-leaf, 



