Euura salicis-nodus (Dalla Torre) (Hymenoptera: Tenthredinidae) and its Hymenopterous Parasites Reared from Spindle-galls of Willow

Abstract

In a communication previously published (Judd, 1952) the writer reported upon studies of insects reared from Pine Cone Willow galls collected near London, Ontario in 1951. At the time this collection was made numerous galls of another type were noted on the twigs of a growth of willow shrubs adjacent to those from which the Pine Cone galls were taken. These galls were spindle-shaped swellings of the twigs and branches and were from three-quarters to one and one-half inches long and, at their greatest width, two or three times as wide as the twigs (Fig. 1). They were confined to a growth of willow which formed a straggling band along the edge of a field, the individual bushes being shrub-like in stature, three or four feet tall. This willow was identified as the sandbar-willow (Salix interior Rowlee) by use of a key to foliage of Salix in Fernald (1950). Most of the galls were separate from one another, forming individual swellings along the twigs. Some twigs and branches bore only a few galls but some bore several, there being as many as eight separate galls along one foot of branch. In a few cases two galls were so closely adjacent that they formed a single bilobed swelling of the twig. In the key to insect galls of willow in Felt (1940) they were identified as spindle-galls caused by the sawfly Euura nodus Walsh.