33 



bers, at intervals every year. This is the more reniarkal)!*^ in that the 

 species has pi'actically l)ecome an indoor one so far as we know, and 

 the individuals found from time to time are therefore evident!}' survi- 

 vors of the original lot first introduced in a previous year. 



The length of life of the mature sawfly is only a matter of three or 

 four day«. It was noticed of the adults that were transferred to new 

 quarters for oviposition, when first issued, that they died in this time. 

 One that was found just casting ofi' its last pupal skin June 10 was 

 isolated on a potted violet on the 11th, was observed living as late as 

 noon of June lo, and was foiuid dead and dry on the morning of the 

 15th. It had evidently lived an active life of only three or four days. 



PARTHENOGENESIS. 



The material received in October, 189T, was taken in charge b}^ Mr. 

 Pratt and confined with potted violets, surrounded b}' a glass cylinder, 

 resting l^pon a base containing sand, which was kept moderately moist, 

 as the plants did not retpiire a very great degree of moisture. Upon 

 this sand there was placed a stem of sunflower, containing pith, and in 

 this the larv?e constructed their cocoons. The first adult was observed 

 March 17, 1898, its appearance l)eing nearly coincident with the 

 blooming of its host plant; a second and third appeared about April 

 7, a fourth April 18, and a fifth was found May 2. All of the imagoes 

 reared were females. 



April 7 the writer noticed young sawfly larvie feeding on the leaves 

 of the plants used in these observations. This was prior to the appear- 

 ance of an}^ except the first issuing adult, and is proof conclusive of par- 

 thenogenesis in this species — a not unusual occurrence in Tenthredi- 

 nidfe, but more commonly met with in certain other families of 

 Hymenoptera, and particularly well known in CVnipida?.^ 



April 16 at least two new broods of the larvavwere observed, the 

 progenv of the females that were found dead April 9, and yet another 

 brood was obtained from the female which issued late in April, fur- 

 nishing still further evidence of parthenogenesis. 



All of the flies reared in May and June were females. A portion 

 were placed with two pots of violets, but not carefully watched, as it 

 was not deemed necessary to do so with this generation, it being the 

 intention merely to note from the time of first egg-laying to the issu- 

 ance of the first fiy of the next generation, and then to follow this last 

 closely, to obtain all stages of the midsummer generation. Only a few 

 larva? hatched, and it was then found that the plants were dying from 



^Parthenogenesis in the Tenthredinid genus Emphytus has been recognized by 

 tiie distinguished zoologist, C. Th. E. von Siebold. In Entoniologische Nachricliten 

 (Vol. X, p. 95), published in 1884, lie records the fact that eggs laid by virgin females 

 l)roduced males in the European species I'J)iqihi/liis ciiirtKs L. and TJ. viemunisln Schr. 



3253— No. 27— (II 3 



