Insects on Osiers and Willows, [april, 



some cause galls on the leaves, others at the ends of twigs, 

 others give rise to swellings on very young twigs ; while the 

 species in question attacks thicker branches, up to, it may be, 

 the thickness of one's arm. 



Cecidomyia saliciperda, Duf. — This gall-gnat measures only 

 3 mm. in length and 7 mm. in spread of wing. The insect is 

 dark coloured, and covered with black hairs ; the sides of the 

 abdomen are reddish. The antennas are whitish, and the wings 

 are white and have white hairs, as also have the legs. The 

 larva or maggot is yellowish or orange-coloured. 



Life History. — Eggs are laid in chains on the bark in May 

 in an average season, and the larvae on hatching penetrate 

 below the bark. By the time the cambium has been reached, 

 it has begun to give rise to the new wood of the year; but 

 the irritating presence of the gall-gnat maggots causes it 

 to form irregular growths, through which the maggots make 

 chambers or tunnels. For a time the bark is able to accom- 

 modate itself to the increased growth without bursting, but at 

 last it gives way and peels off or hangs down in strips, exposing 

 the larval chambers in the browned wood. The larvae live in 

 these chambers till they attain their full growth in the month 

 of April of the year following their hatching. When full grown 

 they pupate near the outside of the chamber, and in May 

 for April, according to the temperature,) the adults issue. 



Attack has been noticed on Salix alba, S. viwinalis, S. triandra, 

 S. purpurea] S, caprca ) and on White Poplar, 



Remedial Measures. — I. A careful observer, familiar with 

 the work of the fly, can recognise the swellings before these 

 have burst ; they are recognisable early, especially on willows 

 with lighter coloured barks. The twigs where these swellings 

 are noticed should be cut away. 



2. The attack generally, however, will not have been observed 

 until a comparatively late stage, in which case there should 

 follow a thorough cutting away of attacked branches so as not 

 to leave any of the pests behind. The branches cut away 

 must not be allowed to lie on the ground as the brood may 

 mature in them. 



5. Infected places can be painted over with tar and some 

 sticky material. This will prevent the escape of a new brood. 



