262 BRITISH BUTTERFLIES. 



Habits of Larva. — The newly-hatched larva (September 18th, 1877) 

 is a very sluggish little creature, not inclined to leave the underside of 

 the leaf, where it is hatched ; they betray their whereabouts by the 

 presence of small flesh-coloured spots which appear on the upper dark 

 green surface of the leaves, the spots gradually increasing in size to 

 blotches of irregular figure, and then turn to a rusty pale brown 

 colour ; and seen from beneath against the light they appear 

 semitransparent and colourless, the tiny larva3 appearing as a dark 

 object against the luminous blotch. By the end of October the lower 

 cuticle of the leaves is often eaten away and the leaves turn brown, 

 but the larvae grow so slowly that in six weeks (November 3rd,) they are 

 only 2mm., in length, and soon after this they take up their position 

 on the underside of the leaves ready for hybernation. In early March 

 the larvae commence to feed again on the young shoots of the plant, 

 seeking the tender leaves, eating a little from the underside of one 

 leaf and then moving to another, and still betraying their whereabouts 

 by the blotches made. Through April they feed up pretty rapidly, 

 rarely staying to clear the whole underside of a leaf, and by the middle 

 of May are full-fed. When moulting the old skin is left attached to 

 the plant like an empty shell, not in the least shrivelled, but split open 

 laterally along the ridge above the legs. When in its last instar the 

 long whitish hairs closely resemble those of the underside of the food- 

 plant and add much to the similarity of the larva to its surroundings, 

 and making it specially difficult of detection ; they appear to restrict 

 themselves entirely to the underside of the leaves, to the colour and 

 appearance of which they assimilate excellently (Tutt). 



The larva hatches in from seven to nine days and escapes by eating a 

 large hole in the crown of the egg, commencing about half-way between 

 the micropyle and the outer margin ; before emerging it has demolished 

 about two-thirds of the upper surface including the greater part of the 

 micropylar area. The time occupied in effecting the escape is often of 

 considerable duration, and in one instance a larva which was observed 

 to have perforated the top of the egg-shell on October 18th, at 7.30 

 a.m., did not leave the egg until some time during the following day, 

 and at 8 a.m. on the second day was found to be resting from its 

 labours, although the hole it had made was amply large enough to 

 permit of egress. 



Larva? of this species hatched in September, 1907, fed during their 

 first three stages exclusively on the cuticle of the underside of the 

 leaves of Helianthemum vulgare, and were never observed resting in any 

 position other than the underside of the leaves. The hybernating 

 stage is, in my experience — one brood only — the third instar; the 

 position, low down on the underside of leaves of foodplant. 



The secretory gland on the 7th abdominal segment appears to 

 be well developed in the third instar, and is probably first functional 

 at this stage (Rayward). 



The larvae emerge in from six to fifteen days, depending upon the 

 temperature. They proceed from the upperside of the leaf, on which 

 the egg was laid, to the underside, and feed there. In that stage they 

 are very difficult to see, as the short hairs assimilate closely to the 

 white underside of the rock-rose leaves. In both Scotland and 

 Durham they feed until well on in their second instar, when they retire 

 for the winter and hide under leaves at the base of the stem. Even in 



