Spathegaster tricolor. 25 



particularly at the tips ; basal joints of the antennae 

 pale ; male and female similar. 



Experimental breeding. I made, in 1875, some ob- 

 servations on the manner in which this species pricks 

 the buds. On July 17 I found several females busily 

 hunting about on the under surfaces of the oak leaves 

 which they finally began to prick, and during the month 

 of August the galls of Neuroterus fumipennis developed 

 on the pricked leaves. I have not made any further 

 experiments with this species. 



[The hairy pea gall is found in June on Quercus pedunculata and 

 Q. sessilijlora. 



Inquilines. Synergus albtpes, S. facialis, and 5. thautnacera all in 

 June and July. 



Parasites. Eurytoma rosae and species of Toyyuius and Pteromahis 

 in July. This gall is often found on Lammas shoots.] 



The Neuroterus and Spathegaster forms just de- 

 scribed had formerly been considered as belonging to 

 different genera, because it was not known that they 

 were alternate generations of the same insect. This 

 view was perfectly justifiable since very important 

 differences exist between the two generations. A com- 

 parison of the galls of the two generations would not 

 lead us to associate the two species with each other, for 

 the difference between them is often much greater than 

 between two wholly distinct species, such as Neuroterus 

 lenticularis and Neuroterus numismatis. I will refer 

 later to the important distinction that the flies in the 

 one generation belong to both sexes, and in the other 

 exclusively to the female sex. The parthenogenetic 

 propagation of Neuroterus is constant, and is now so 

 satisfactorily established that it requires no further proof. 



