Insects, etc.. Injurious to the Gooseberry. 275 



do. The first fly hatched on the 25th of July. Whether this 

 constituted a second brood or a third brood I cannot say. Cameron 

 says there are two generations during the year. 



The larvffi feed on the red currant as well as on the gooseberry, 

 and I have one note of its occurrence on the white currant. 



It appears to be known also under the two following names; 

 Nemahis cathoraticus, Foer, and iV". pehtcri, Andre. 



Eefekences. 



(1) Cameron, P. ' Monograph of British Phytophagous Hymenoptera,' vol. II., 



p. 66 (1884). 



(2) Theobald, F. V. -lournal S. E. Agri. Coll., No. 11, p. 39 (1902). 



THE GOOSEBERRY EMPHYTUS. 



(Emphi/tus r/ros.'i/i/uriw. Kl.) 



This species of sawfly feeds on the gooseberry in England, but 

 is too uncommon to do any harm. 



Parthenogenesis in Gooseberry Sawflies. 



Parthenogenesis frequently occurs amongst the sawflies. It has 

 been observed in N. ribesii, N. conaohriims and others by numerous 

 observers. 



Siebold (Beitr. zur Parth. d. Arth., pp. 107) and Kersler (Die 

 Lebens geschichte von CeutorhyncJuos sidcicollis and Ncmatu^ ventri- 

 cosus. Cassel, 1866) have both observed it. 



"There is not the slightest doubt," says Cameron, "that Nematus 

 ribesii possesses the faculty of laying unfertilised eggs which in- 

 variably yield only males." 



This phenomenon was noticed as long ago as 1820 by Eobeit 

 Thorn (Memoirs Caledonian Hort. Society, IV., pi. 2), but he 

 imagined that male and female larvae copulated. 



The eggs may be laid immediately after the females lea\'e the 

 cocoons and when these unfertilised females have been examined 

 after oviposition no traces of spermatozoa were discovered in the 

 ovaries, while they are easily seen in those that have been fertilised. 

 The first statement made by Cameron was subsequently modified, 

 for in the Appendix to Vol. I. of his ^Monograph (p. 218) he says that 

 the virgin females of Ahia fasciata and N. ribesii yielded males and 

 females. In N. rufa, etc., males and females were also produced, 

 but in Hemichroa rufa, Uriocampa ovata, Nemahis appcndicvlatus 

 and others withoixt exception females only were bred. 



T 2 



