February, '17] ZAPPE: diprion oviposition 189 



Hosts for Egg-Laying 



In captivity the female sawflies have laid eggs in several species of 

 pine as follows: 



Pinus excelsa, Japan or Bhotan pine 

 Pinus cembra, stone pine 

 Pinus Jlexilis, limber pine 

 Pinus strobus, white pine 

 Pinus koraiensis, Korean pine 



> Five needles 



Two needles 



Pinus sylvestris, Scotch pine 



Pinus densi/Iora, Japanese red pine 



Pinus montana, mugho pine 



Pinus resinosa, red pine 



Pinus ponder osa, bull pine 



Pinus laricio var. Austriaca, Austrian pine 



Pinus rigida, pitch pine Three needles 



A few eggs were also laid singly on white spruce, although attempts 

 to obtain eggs on hemlock, larch, Japanese umbrella pine, and white 

 fir, failed. Out of doors the sawflies showed a decided preference for 

 the five-needled pines, although larvae have been found feeding on other 

 species. Pinus excelsa seems to be preferred above all others. 



Parthenogenesis 



Copulation was not observed and seems to be whoU}^ unnecessary, 

 as the eggs develop and hatch just the same if males are not present. 

 Apparently it makes no difference as to the number of eggs laid whether 

 or not males are present at the time the females are ovipositing. Some 

 oviposit when males are present, others do not; the same is also true 

 when males are absent. 



In three cases the adults reared from eggs laid by virgin females 

 were all males, but this may not hold true upon further investigation. 

 In fact, some of the second brood 1916 cocoons are of large size and 

 look as if they might yield females. 



Number of Eggs Laid 



The female sawflies usually begin to oviposit about one day after 

 emerging from the cocoons and live for about seven days, while those 

 individuals which do not oviposit die in four or five days. Length of 

 life of males varies, some live longer than the females and some do not. 



Upon dissecting the bodies of females from overwintering cocoons 

 an average of 58 eggs per female was found, while the eggs in a female 



