44 



Priophorus cequalis, Nort. — This is quite a small species, the perfect fly being hardly 

 one-quarter of an inch in length. The larvae, however, sometimes occur in sufficient 

 abundance to seriously affect the foliage. They are of a pale yellowish colour, with the 

 back greenish. The head and last segment are black and there is on each side a row of 

 black spots, eleven in number. Upon the back and on each side are two rows of small 

 tubercles, bearing long white hairs. Ihe species is apparently double-brooded as from 

 larva? obtained in June the flies appeared a month later, and I have observed similar 

 larvae in August and September. Late last August I saw a small poplar nearly defoliated 

 by larva? apparently of this species, and two or three weeks later, found similar ones on 

 willows. (Note. In the Fifteenth Annual Report I referred to this species as Cladius 

 isomera, Harris, but further examination seems to refer it to P. cequalis. The larvae of 

 C. isomera, which also occurs here are, however, of very similar appearance and habits. 

 The European species of this genus are recorded as feeding on willow, poplar, cherry, etc.) 



Dolerus arvensis, Say. — One-third of an inch long of a shining blue-black colour, ex- 

 cept the partly red^horax ; wings smoky. Larvae 22-footed grubs feeding in June. 



Cephus integer, Nort,, is an insect having the abdomen more compressed, and of a 

 more generally elongated shape, which has been figured and described by Prof. Riley, 

 (Insect Life, vol. i., p. 8) as injuring the young shoots of various species of willows in 

 and near Washington. The female inserts the egg a few inches below the tip of the 

 shoot, and afterwards girdles the twig. The larva? bore down through the pith. The 

 ravages are indicated by the wilting of the twigs, and a scorched appearance of the 

 plants. The insect occurs in Canada but I have seen no mention of any attack by it. 



For much of our knowledge, of the species of saw-flies forming galls, or subsisting 

 upon the galls of some other insects, we are indebted to "Walsh, who bred many of the 

 species, and described them in a paper published in the Proceedings of the Entomological 

 Society of Philadelphia, Vol. V, page 284. He enumerates about a dozen species belong- 

 ing to the genera Euura and Nematus. The galls produced by the former genus are upon 

 the twigs, being usually enlargements or deformations of the buds, and may be readily 

 found on examining our native willows Salix cordata and Salix humilis. 



Upon the leaves of the same willows during the summer may sometimes be found in 

 great numbers small galls varying in shape, but generally spherical or oval, which on being 

 opened are found to contain small green larvae, and which are produced by different 

 species of Nematus. These insects, however are so much alike that any satisfactory de- 

 scription of them would be far too long and technical for the purposes of this paper. They 

 are, however, closely related to the saw-fly so destructive to the currant and gooseberry 

 bushes, and differ chiefly in being smaller and less robust/ 



There are also several species which are known as inquilines, or "guests," because 

 they do not produce galls themselves, but subsist upon those formed by the species above 

 named, or by certain small flies which will presently be mentioned. 



There is another gall, not mentioned by Walsh, which is very abundant, not upon 

 our native willows but upon S. alba, the common white or European willow. Sometimes 

 nearly every leaf will be attacked, and perhaps will be almost covered by oval, or oblong 

 sessile galls, which become reddish as they mature. They produce a very small fly, about 

 one-sixth or one-fifth of an inch in length, and which is apparently the species called 

 Messa hi/alina, Norton. (Probably a European Nematus.) 



DlPTERA. 



The insects belonging to this order, which are found injurious to various species of 

 willows, are all minute forms, such as are known as gnat-flies or midges, and the majority 

 of them belong to Cecidomyia, to which extensive genus belong, also, the destructive 

 clover-midge, Hessian-fly, etc. There are, however, several species of Diplosis, another 

 group of midges, among which is found the wheat midge, which are uninvited guests of 

 the Cecidomyia^. 



Everybody must have observed the large swellings at the tips of willow twigs, which 

 bear so much resemblance to the cones of pines, or spruces. These are the result of the 



