2l8 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



ers were plump and still producing though the older of the 

 progeny were pupae about ready to molt. At this date the 

 migrants in some galls were already winged. At this time 

 most of the galls pop open on one side, a circular hole for exit 

 being thus provided. The opening into the gall from the ven- 

 tral side of the leaf was apparently used for exit in the galls 

 of less vigorous growth which did not split on the side. So far 

 as the examination of many galls revealed all the progeny of 

 the stem mother acquired wings, no apterous form except the 

 stem mother being found in any gall examined. 



The migration took place the last of June and first of July, 

 but the fate of the migrants and their progeny was not ascer- 

 tained. It is probable that they, like the European elm Tetra- 

 neura and Tetranetird graminis, accept some grass species for 

 the summer host and that migrants from grass return to the 

 elm in the fall to deposit the true sexes which consign the win- 

 ter egg to the crevices of the bark. 



Discussion. 



Galls of this species I have collected at Orono, June 30, 1904; 

 July 3, 1905 ; June 26- July 6, 1909, and specimens of galls with 

 winged individuals were sent me from North Berwick, Maine, 

 July 12, 1906. The species of the elm was not recorded except 

 for the 1909 collection which was made from an ornamental 

 elm, Ulmus montana var. Camperdown pendula. 



I do not know that ulmisacculi will prove to be distinct from 

 European species. But the European literature on the Tetra- 

 neura of the elm, — ulmi, alba and rubra, is not definite even for 

 Europe, and it is certainly not desirable to add to the confusion 

 already existing by trying to merge ulmisacculi with any of 

 them unless the identity can be definitely proven. A brief dis- 

 cussion of the difiference between ulmisacculi and the European 

 species is of interest in this connection. 



"Deep red hairy galls"* would be sufiicient to exclude ulmi- 

 sacculi from riibra. Lichtenstein (1880) gives in his table 

 "Insect white, stem mother with 4-jointed antenna," for T. 

 alba, which would exclude ulmisacculi, as this is a decidedly 

 dark and not a pale species. In the same table Lichtenstein 

 gives "Insect black, the stem mother with 3-jointed antenna," 



*Buckton, Vol. Ill, 131. 



