PERONBA CRISTANA. 221 



The Larva. 



I should observe that in order to get the larvae fed up before 

 I left home for an engagement early in June I kept both them 

 and the ova indoors, and under these conditions the dates on 

 which they arrived at the various stages would be somewhat 

 more advanced than would be the case if they had been kept 

 out of doors, for of course there are always periods of cold 

 weather in our springs, during which an insect exposed to the 

 elements advances very little, if at all ; and this does not apply 

 to ova kept or larva reared indoors to such a great extent, 

 because the cold snaps are not then so much felt, even though 

 there is no fire in the room, 



A larva kept in a small glass-top tin box from emergence to 

 pupation hatched on April 26th. It was then about 1 mm. in 

 length ; the head and prothorax were black and glabrous ; the 

 remainder of the segments were pale brownish-green, and semi- 

 transparent, the alimentary canal showing plainly. I fed this 

 larva whilst it was in the first instar on blackthorn, transferring 

 it afterwards to plum. The larva on emergence spins the black- 

 thorn buds and flowers to the adjoining stem, and feeds and 

 dwells inside the web so formed ; sometimes it is found within 

 the petals and sometimes between the calyx and the corolla. 



On May 1st this larva had changed into the second instar, 

 and was then about 2 mm. in length ; the head was black, the 

 prothorax was light brown, and both were highly glabrous. The 

 remainder of the segments were light yellowish-green. On 

 May 4th the third instar was reached ; it was now about 3 mm. 

 long ; the head and prothorax were both glabrous ; the head 

 black ; the prothorax was dark brown ; otherwise the colour 

 was the same as in the last instar. The larva was still very 

 transparent and the alimentary canal was plainly visible. 



On May 11th the fourth instar was reached. The larva was 

 now about 5 mm. long ; the head and prothorax were intensely 

 black and glabrous ; otherwise it was very similar to the last 

 instar, except that the divisions between the abdominal segments 

 in the dorsal area are much darker green than the segments 

 themselves. There was no trace of a chitinous anal plate in 

 this or any of the previous instars. 



The fifth and last instar was reached on May 21st. A great 

 change had now taken place in its appearance ; it was about 

 12 mm. long, of average stoutness ; the head was dark amber- 

 coloured, with darker shading around the mouth ; it was highly 

 glabrous. The prothorax was greenish-brown and not very 

 glabrous, with darker shading in front and at the rear ; below 

 the thoracic plate, when viewed laterally, are two large black 

 tubercles on each side ; down the centre of the dorsal area, and 

 commencing at the rear of the prothorax, is a narrow grey-green 



