THE CANADIAN ENTOMOLOGIST. 297 



of any transverse plates or fibres as in S. ovum and S. oviilum. Length, 

 ,75 to 1.5 inch ; diameter, .10 to .25 inch. Very like the Cecidomyidous 

 gall S. nodulus on the same willow (Proceedings of the Phila. Ent. Soc, 

 Vol. 3, page 600), but is much larger, is polythalamous instead of 

 monolhalamous, and occurs near Rock Island, 111., in quite a different 

 locality. Analogous willow galls are made in Europe, not by a Euura, 

 but by several small species of Nematus. (Westw. Introd. 2, p. 105.)" 



Gall S. nodus is very common on Salix longifolia along the streams 

 of northern Colorado. Mr. Walsh was familiar with the male of this 

 insect, but knew nothing about the female. His description of the 

 former is given in a comparative way with reference to Euura S. ovum. 

 In my work with Euura S. nodus, a study was made of the winter and 

 spring stages. 



On the 6th of Jan , '06, a large number of galls were collected along 

 the Big Thompson Creek, in the vicinity of Loveland. These galls were 

 placed in breeding cages and kept in the laboratory of the Entomological 

 Dept. of the Colo. Ag. College. A large number of galls were opened at 

 this time, most of which contained larv», each one enclosed in a delicate 

 cocoon, and from one to three in each gall, but usually not more than 

 one. Both living and dead galls contained perfectly healthy larvae. 

 The first adult emerged on the 22nd of February. They then continued 

 to emerge until the 6th of March, when the last of the lot made its 

 appearance. 



After the emergence of the first adult, a number of galls were cut 

 open and examined for puppe. This stage of the insect was not studied 

 by Mr. Walsh, or not known by him at the time of his description of the 

 adult. As found in the galls, their length varied from .25 to .30 of an 

 inch. 



Many more galls were collected and examined on the 4th of March. 

 All galls which contained insects of the Tenthredinidge family at all, 

 contained them in the larval stage, showing that the unnatural conditions 

 existing in the laboratory caused an early transformation from larvte to 

 adult of the previous lot. The first adult emerged from these galls on 

 April 4ih. There also emerged on this date a small Chalcid parasite. 



On the 26th of March a great many galls were collected along the 

 Poudre Creek, just on the outskirts of the City of Fort. Collins. On the 

 13th of April a couple of Ichneumon-fly parasites were found in the 

 breeding cage, and on the 24th a large number of Euura began to emerge. 



