212 Observations on Pim})la pomoriim 



blossoms" be opened the small white apodous larva of the weevil will be 

 found in the centre. In many cases the larva of the weevil will be found 

 to be dead, or weakly, and accompanied by a smaller larva not very 

 unlike it in appearance. This latter larva in most instances will prove to 

 be that of Pimpla poniorvm, which forms the subject of the present 

 investigation. 



During the past year I have carried out a preliminary investigation 

 of the parasites which attack the apple blossom weevil, in the belief that 

 a possible method of control might eventually be afforded by the utiliza- 

 tion of these natural agencies. In this connection it is noteworthy that 

 Marchal (1907, p. 15) quotes the experiments of Decaux who was im- 

 pressed by the multitude of ichneumon flies, or Braconids, which came 

 out of apple buds attacked by A. pomorum. Instead of immediately 

 burning these buds as was usually done, Decaux preserved them in boxes 

 covered with gauze, raising the latter from time to time to allow of the 

 escape of the parasites. In 1880 he put this method into use and collected 

 in Picardy five hectolitres of buds from 800 apj)le trees. By this means, 

 it is stated, that more than a million Anthonomi were destroyed and 

 about 250,000 parasites liberated w^hich, in the following year, were 

 valuable aids in the destruction of the weevils. The orchards treated 

 were surrounded by cultivated fields and consequently isolated from 

 neighbouring fruit plantations. It sufficed to repeat the same operation 

 during the following year, in order to prevent serious damage from the 

 weevil during the succeeding ten years, so thoroughly had the parasites 

 done their work. 



The results obtained during one year's preliminary investigation con- 

 firmed my surmise that the apple blossom w^eevil is, in certain localities, 

 at any rate, in this country, equally heavily parasitised. Owing to the 

 great difficulties in obtaining labour entailed by the War, it has not been 

 found possible to prosecute these investigations any further at present, 

 as very considerable quantities of affected blossoms are needed from 

 various parts of the country. Nevertheless, the facts already observed 

 are, I think, of sufficient importance to merit publication. I must express 

 my indebtedness to Mr Claude Morley, who examined a pair of the adult 

 ichneumons submitted to him and identified them as belonging to the 

 species Pimpla pomorum Ratz. 



2. THE FEMALE. 



This species was first described by Ratzeberg (1848, p. 96) from 

 females bred by Reissig from Anthonomus pomorum in pear blossom 



