Insects, etc., Injurious to the Plum. 



395 



parts of Britain in 1906 showed the extraoidinary parasitic Procto- 

 trupids of the genus Aphclojms. Tlie infected individual looks as 

 if its alxlomen were bifurcated, for the "gall" produced by the 

 parasite equals or rivals in size the alidomen of the host. 



These " galls," for they are nothing more or less than aviimril 

 galls, have Ijeen previously noticed by (liard (V) in France, and he 

 speaks of thein as " Tlbj/Iaciji." These growths are formed by a 

 gradual dilatation of the skin. This sac is attached to the back of 

 the insect. In it lies the Ajilicloims larva, and here it passes the 

 later stages of its development. 



Frecpiently I have found these sacs Ijreak away nnd fall to the 

 earth ; the homopteron flies on un- 

 concerned, just as it seems to ha\'e 

 been by tins additional load, (.liard 

 states that the host niu)' die. J\Iore 

 often this sac remains attached to the 

 host until the Proctotrupid larva es- 

 capes, and falls either to the ground 

 or on to the liranches. It then pupates 

 in a coarse case very similar to that 

 formed by the Braconidiv. TiM^Aiiliilniiiis 

 lar\a is long, and has a transverse row 

 of long stiff bristles on each segment. 



The effect of these hymenopterous 

 parasites is very marked. (Hard refers 

 to them as causing parasitic castration 

 (Castration parasitaire). They reduce 

 the size of the external genitals, fre- 

 cpiently to such an extent that only 

 vestiges remain, and at the same time 

 alter their form. 



The other important group of parasites are the larva- of the 

 dipterous family of PqmvrnIiJfr. 



Several larva-" were found in CliJorita: sent from Kent belonging to 

 a species of Afdcnvni. In France the species fountl by (.iiard working 

 v\dth the Proctotrupids appears to be Afclmnni .■<jiiirlii, Meigen. The 

 effect of tliese larvie is also to produce parasitic castration. I do 

 not know if any changes take place in the female hop]:iers.* The 

 Atelenura larva lives within the body of the Typhlocybida?. The 

 parasitised abdomen swells to such an extent that it passes well 

 beyond the wings, so that an invaded specimen can at once lie told. 

 * Giard distinctly states so. 



\F. Edenilcii. 



Fir:. 1^(14.— YKI.I.nW LEAF HuPPKU 

 ATTAOKEl' I!V A IMt' ifToTlJUPIi', 

 A, finihina. 



