13 



SOME ACCOUNT OF THE LARV.E OF PCECILOCAMPA 



POPULI. 



By James Douglas. 



Possibly a few notes on the rearing and changes of the larvae 

 of Poecilocampa popidi may be of interest to your readers, espe- 

 cially as most of the text-books give very imperfect descriptions 

 of these larvae. I obtained several batches of eggs in December, 

 1901 ; the females, unlike those of Diloba cceruleocephala or 

 Trichiura cratcegi, being attracted by light. The eggs were kept 

 in a room facing east, with an occasional fire. This proved 

 rather too warm a temperature, for the larvae (then 4 mm. long) 

 emerged from March 2'2nd to April 3rd, to the number of about 

 one hundred. In consequence of this early hatching, and the 

 lateness of the season, I was almost in despair of rearing them, 

 none of their usual food-plants showing even buds ; however, I 

 managed to find a Siberian crab with expanded bracts, and on 

 these the larvae flourished until the apple-trees were sufficiently 

 advanced. The larvae were then of a dark bluish tint, with short 

 dark hairs, the subdorsal lines orange, and the head much nar- 

 rower than the first segment. They grew to the length of 

 10 mm. by April 9th, when they began their first moult. Im- 

 mediately after this the ground colour, including the head, was 

 light ochre thickly sprinkled with dark purplish-blue dots, black 

 spots in pairs on each segment ; subdorsal lines orange, with white 

 spots between the sixth and seventh segments. A few hours later 

 the ground colour became a light bluish grey, and the head 

 black. There were no signs of any red blotches or tubercles. 

 This moulting continued until April 27th, t. e. the last larva did 

 not change until six days after the first had completed a second 

 moult, which began on April 21bt, and continued until May 15th. 

 In the early days of this stadium the colour was similar to that 

 of the previous one, except that the black spots were not so con- 

 spicuous ; size 14 mm. Six days after the moult red blotches 

 described in the fifth stadium began to show signs of appearing, 

 the colour being at first dirty yellow ; curiously enough, six of 

 the larvae showed no signs of this change, the blotches remaining 

 black ; but I was unable to detect any dift'erence in them after 

 the next moult. 



Third moult, May 6th to June 3rd. General colour lighter, 

 and the whole appearance more variegated ; marks on the second 

 segment redder ; the larvae, when at rest, having a curiously 

 flattened appearance. Size, May 6th, 25-26 mm. ; May 11th, 

 32-33 mm. 



Fourth moult, May 15th to June 15th. Ground colour 

 creamy white, thickly speckled with black ; dull red blotch (not 

 tubercle) on second segment on either side of dorsal line ; third 



