NOTES ON PIERIS MANNI, MAYER. 39 



with ^ving■s open to the sun, and, should a male approach, she flattens 

 down her wings and raises her body to prevent pairing. 



Egg. — Cylindro-conical like a shell (obus) in shape, resting on a flat 

 base, and sometimes slightly lopsided. Height l-45mm., greatest diameter 

 0-5mm. Colmir and Stirface. — When first laid, the egg is almost white, 

 with only a slight greenish-creamy tinge. On the day following it is of 

 a decided creamy colour, which continues to deepen to a pale yellow on 

 the third day, becoming light yellowish-orange before the emergence 

 of the larva which takes place on the fifth day in the height of summer. 

 Cold weather retards the process as might be expected. Surface 

 shining, pearl-like. Scidptiirin!/: There are as a rule twelve vertical 

 or main ribs, but sometimes only eleven. These rise a little above the 

 actual summit of the egg, forming around it a close palisade easily 

 distinguished from the mass of the egg when it is held up to light. 

 In some eggs a few of the ribs do not exceed the summit, thus causing 

 very slight breaks in the palisade. These main ribs, of a rather 

 lighter yellow than the rest of the egg-surface, are high and wide. 

 The ridges are rounded off, not sharp. On them can be seen with the 

 aid of a lens, numerous and minute transverse ribs, or rather one 

 notices the little incisions, separating these ribs. These secondary ribs, 

 though low, are wide in proportion to the width of the incisions. 

 [These observations were made with a hand lens ; no microscope 

 ■being available.] 



The hatching and habits of young larva. — Eggs laid on Sep- 

 tember 1st and 2nd hatched on the 9th of that month ( = 7-8 days, 

 whereas at the beginning of August the egg-stage lasted but five days). 

 I have not seen a larva in the act of emerging, but I believe it eats its 

 way through the side of the egg, for there is a tear in the egg-shell, 

 showing the trace of mandibles. The shell remains upright, but is 

 considerably shrivelled. The young larva does not eat it, apparently. 

 It soon attacks the parenchyma on the underside of the leaf, eating 

 little holes in it. Although its growth is rapid it is not by any means 

 a continuous eater, nor does it eat much at a time. It feeds by day, 

 and also I believe at night, but T have no absolute proof of this. It is 

 not at all easy to see, and it further protects itself by resting on the 

 undersides of the leaves. It spins a thread of silk wherever it goes, 

 and makes a little carpet for its resting-place, and on this it fixes 

 itself for the moult. Unless it is moulting, it can easily be made to 

 drop from the plant with a sharp tap on the stem (less easily when 

 young). Between September 15th and 17th nearly all the larvfe 

 which hatched on the 9th passed the first moult. By the 21st many 

 had already attained the third stage, whilst others had nearly reached 

 the end of the second stage. The rate of growth dex:)ends to a great 

 extent on the temperature. During the first stage the weather was 

 cold, particularly at night, and progress was therefore less rapid than 

 between the first and second moults, when the weather was warm and 

 damp. The young larvae certainly appear to avoid sunlight. On 

 September 26th several larvfe were lying up for the third moult, and a 

 few were in the fifth stage by October 1st, others passing the fourth 

 moult on the 2nd, 3rd, and 4th. The pupse were formed between 

 October 14th and October 20th. The weather was generally damp, 

 •overcast, and often foggy towards the end of September and in Octo- 

 loer. There was a cold spell on the 9th and 10th, but it was of short 



