42 



tibiiiG ut apex furnished witli two dark spurs. Wings hyaline, veins 

 fulvous, stigma basally fulvous, terminally inclining more to ximber, 

 costa same, third submarginal cell nearly square, the nervures sepa- 

 niting the three, whitish. Average length 7 mm., wings 5 mm. 



Imarjo. — ^ . Differs from $ by being smaller. Head with eyes larger- 

 Abdomen nearly black. Posterior legs with the femora testaceous 

 throughout, tarsi darker than in ? . Wings with veins more deeply 

 marked, as also the stigma. Average length 6 mm. 



Habitat. — Peoria, Illinois, on Salix alba. Described from twenty 

 bred specimens. 



Natural History. 



EUUEA SALICICOLA. 



This species is found only on new limbs of the Sali.c alba. The 

 matured insect is seen flying about the willow trees the latter part 

 of April, and at this time the eggs are inserted in the tender bark 

 of the young shoots, both those growing out of the trunk and from 

 the top of the trees. The female makes longitudinal slits in tlie 

 bark and inserts an egg in the cavity. The larva bores into the 

 center of the limb and subsists upon the pith, pushing back the 

 sawdust like substance not digested. It progresses about an inch 

 during the summer and upon the approach of winter turns about, 

 facing the direction from which it first entered and spins around 

 itself an oval silken cocoon of a yelloAvish color. Inside this cocoon 

 •the larva remains during the winter months, changing to a pupa 

 the following April. In a trifle less than two weeks after it has 

 entered the pupa state, it emerges as a perfect insect through the 

 same place it first entered as a larva. The puncture of tlie bark by 

 the female causes no gall-like swelling or elevation, but the presence 

 of the insect is determined by a discoloration of the Ixirk. 



PARASITE. 



The larvae of Enura saUclcola are parasitized by the larva of 

 Eurytoma sfudiosa Say (according to the determination by E. T. 

 Cresson). The kirva and pupa are undescribed and I append tlie 

 following, together with a reproduction of Say's description of the 

 imago. 



Larva. — Color milk white, l)ody uniform, head inclining to umber ; 

 length 5 mm. 



The presence of the parasite is determined by a dark spot upon 

 dorsal side of the larva of its victim; the Imago emerging from the 

 pupa. 



