227 



NOTES ON GEOMETRA VERNARIA. 

 By G. M. Russell, B.Sc. 



Having recently bred from the egg- state a series of G. ver- 

 naria, I have thought that a few notes on the life-history of the 

 species may be interesting. A worn female, taken in July of last 

 year, having been placed with a few leaves of Clematis vitalba in 

 a box, deposited eggs on the 25th of that month. The greenish- 

 yellow eggs were laid on the leaf stems, and were placed one on 

 the other, forming perfect cylinders standing out perpendicularly 

 to the stems. The batches contained from two to eight eggs, 

 which are remarkable for their geometrical accuracy, having 

 perfectly plane ends at right angles to the curved sides. A 

 cylinder of six eggs was about 2 mm. high; each egg was, there- 

 fore, a right cylinder about J mm. high, and of cross section 

 elliptical; major axis about '8 mm., minor axis "6 mm. 



The larvse emerged on August 9th, without displacing the 

 egg-shells from the cylindrical arrangement, the holes through 

 which they made their exit being in the curved sides, and, in any 

 cylindrical batch, nearly along a generating line. The larvae 

 were pale green in colour, and fed very slowly. About the middle 

 of September, when they had attained a length of 1 cm., they 

 became very sluggish, only fed on warmer days, and began to 

 change in colour, the rather bright green gradually giving place 

 to a dark brown — i. e. the same colour as the dry stalks to which 

 they attached themselves in the usual geometer manner, and 

 were then only distinguishable with difficulty. They remained 

 in this way the whole winter without movement, although if 

 brought into a warm room they soon began to show signs of life. 

 They were first supplied with food on March 12th. Two or three 

 ate very sparingly, but were again quiescent during cold weather. 

 On April 18th a green tinge was observed at the two extremities 

 of the most advanced larva. This colour-change gradually spread 

 from segment to segment, until by May 5th this larva had become 

 wholly green, and by the middle of May all the larvae had re- 

 turned to their original bright green colour. They now fed 

 regularly, although mostly at night, when they were more active. 

 On May 30th they began to spin up, drawing together two or 

 three leaves of the food-plant, fastening them with a few strong 

 threads, and pupating in the space so formed. 



Larva : — Length, when full-fed, 29 mm. Head dark red- 

 brown, cleft at top ; face paler. Second segment cleft, forming 

 two prominent pointed protuberances. General colour green. 

 An obscure pale dorsal line formed by a number of white dots ; 

 a spiracular line, a narrow median line underneath, and another 

 between this and the spiracular line, all formed by white dots. 



T 2 



