8 Life History of the Strawberry Tortrix 



and they gradually increased in number until the middle of the month- 

 Most of the eggs in 1917 were laid during the first half of November* 

 as during that time numbers of eggs were laid in the boxes in which the 

 moths were brought from Walton. In 1918 eggs were found on October 

 25th, but owing to the scarcity of moths due to the killing of the larvae 

 by Chalcid parasites, it was difficult to tell how long the moths lived. 

 None were found after the middle of November. 



Two moths were found about two feet from the ground on some sticky 

 bands on apple trees near which some strawberry plants had been 

 heeled in. 



The following table shows the life history of the pest in 1917. This 



seems to be a fairly normal one, but there are seasonal variations as 



mentioned above. 



Length of 

 life of the 

 Stage When found various stages 



Caterpillar Beginning of May — middle of June . 4-5 weeks 



Pupa During June 2-3 „ 



Moth Last week in June — end of July 4 „ 



Egg Last three weeks of July 1 week 



Caterpillar Mid July — beginning of September 4-5 weeks 



Pupa Third week in August — end of third week in September 2-3 ,, 



Moth Second week in September — third week in November about 8 ,, 



Egg Beginning of November — middle of May about 6 months 



The eggs are laid singly usually on the outside of the stipules, but 

 occasionally on the lower part of the petioles. Two or three eggs may be 

 present on one stipule. 



The egg is very flattened, and broadly oval in outline, measuring 

 0-86-0-96 mm. in length and 0-64-0-69 mm. in breadth. The shell of 

 the egg is of a silvery white colour, beautifully sculptured, being covered 

 all over with a raised network which is best seen round the edges while 

 the developing larva is still present (PI. I, fig. 1). The developing larva is 

 at first yellowish, but later assumes a reddish orange colour. The egg is 

 easily seen owing to the whitish rim of the shell which extends beyond 

 the developing larva. 



The larva varies according to its stage of development, so much so, 

 that at first I thought I was dealing with two different species. 



In the young larval stages the head and the first thoracic plate are 

 shining black, but in the older stages they are yellowish. 



I watched a larva about 6 mm. long, with a black head and thoracic 

 plate, in the process of moulting, and found that the head and thoracic 

 plate of the remaining larval stages remained yellow. 



