REPORTS BY THE HONORARY SCIENTISTS. 211 



ing to the species, e.g., under bark, in fungi, in flowers and fruits, 

 and in galls on leaves or stems. Some of the best known and 

 most injurious are not found in marked swellings or galls, e.g., the 

 Hessian fly maggots, so destructive to the stems of wheat and 

 barley, and the maggot of the wheat midge, injurious to the young 

 grain. The gall-making species are the commonest, and the 

 galls inhabited by the maggot are to be found on many different 

 plants, both herbaceous plants and trees. More than one species 

 may attack the same tree, and it is not common for the same 

 species to lay on plants far apart in relationship. 



Of the gall-gnats whose galls are found on trees, several are 

 not uncommon on the willow, the galls being found on the 

 youngest shoots, or in two-year-old and older twigs, or in the 

 bud at the apex of the twig, or on the willow leaves, or on 

 willow flowers. The galls examined in the specimens sent in, 

 were all terminal. The galls contained small maggots. I bred 

 out the adult insects from the galls, and they proved to be 

 Cecidomyia heterobia, as determined by Kieffer. I also bred out 

 along with the gall-gnats a number of beautiful little four-winged 

 Chalcis flies. These latter lay their eggs in the galls, and their 

 maggots on hatching feed off the maggots of the gall-gnat. 



The attack of this gall-gnat on willows that were being 

 grown for wicker-work was very severe, and the money loss 

 was considerable. 



As to the plants attacked, Mr M'Rae wrote me : " Attack is 

 entirely confined to our best hard brown-skinned varieties, viz.. 

 Black Norfolks, Black Mules, and Spaniards, and these sorts, 

 especially Norfolks, are the very best osiers grown for buff 

 wicker-work." These are all varieties of Salix triandra, well 

 known in basket-making. 



Later Mr M'Rae wrote me as follows : " We cut the whole 

 crop down early in the summer, and burned it. The plants 

 threw up a fairly strong second growth, and they were also badly 

 affected, but not quite to the same extent as the early crop." 



Pupation in the case of some species of the gall-inhabiting 

 maggots is in the ground, but, as I have written above, the 

 pupal stage of C. heterobia is passed inside the gall. The 

 remedy, therefore, is to cut away the galls and burn them before 

 the maggots have come to maturity. Mr M'Rae has fought 

 this pest strenuously, and it will be interesting in another year to 

 see whether the infestation repeats itself. 



