THE LIFE-CYCLE OF PENTHINA SOROCULANA, ZETT. 181 



and the lobes were not as prominent as in previous instars ; the 

 antennae were very prominent, although not noticeable 'pre- 

 viously. The frontal plate was lighter in colour than the head 

 itself, and had two black dots near the centre ; there were two 

 other black dots outside the antennae. The segments behind the 

 prothorax were pea-green in colour ; the prothoracic plate was 

 rather lighter pea-green ; the alimentary canal showed as a dark 

 green dorsal stripe, and there were two, in appearance similar, 

 subdorsal stripes above the spiracles. I could not see any 

 signs of an anal plate ; the tubercles were prominent and light 

 coloured ; the spiracles were very small and inconspicuous ; the 

 claspers and prolegs were pea-green without any darker shading ; 

 the spines were light coloured and of about the average length 

 and number that obtain in larvae of the Tortrix group. The 

 larva tapered greatly to anal extremity, and rested with head 

 flattened out. 



On August 16th the larva had increased in length to 16 

 mm,, when it was full grown. Three days later it had not 

 increased in size ; the pea-green colour was deeper, and the 

 stripes were not so prominent. It was evidently commencing to 

 pupate. 



In order to pupate, the larva (in confinement) spins together 

 two birch leaves, and forming a silken lining to the pocket so 

 formed pupates therein. 



The pupa is 8 mm. long, and measures across the dorsum 

 1*75 mm. broad. The colour of the wing-cases and head are 

 dull greenish buff, of the abdominal segments dull brown with a 

 slight green tint, darker on the dorsal area, and with the 

 divisions of segments darker; the covering of the head projects 

 slightly in the shape of a bulb, but there is no trace of anything 

 in the nature of a cocoon opener. The antennae cases project 

 rather prominently from the surrounding portions of the pupa ; 

 each of the abdominal segments has two rows of about a score of 

 spikelets, each pointing rearwards. The wing-cases extend to 

 near the rear of the third abdominal segment ; the abdomen 

 tapers regularly and gradually from the fourth abdominal to the 

 anal segment, which is bent over towards the ventral surface 

 and is furnished with several hooks which keep the pupa in 

 position in the cocoon. The surface of the pupa is not in any 

 way glaucous. 



The imagines emerged in May last. 



Youlgreave, 



South Croydon ; 



July 13th, 1922. 



