214 



INSECT LIFE. 



made by gall-flies (family CynipidcE). The student 

 should learn the different species of oaks that grow 

 in the locality, and should always label the galls col- 

 lected with the name of the particular species of oak 

 on which they were found. The particular time of 

 the year in which the galls are developed should be 

 determined, and an effort should be made to breed 

 the adult gall-flies. Many species of gall-flies under-' 

 go their transformations within their galls, while in 

 other species the full-grown larva leaves the gall and 

 enters the earth to transform. In the former case 

 the adults are most surely obtained by leaving the 

 galls on the trees and inclosing each in a little bag of 

 Swiss muslin. And in the latter case care must be 

 taken not to collect the galls before they are mature, 

 else they will wither and the contained larvag perish. 

 In breeding species that pass the winter in their galls, 

 the galls should be left out of doors till spring to pre- 

 vent the galls becoming too dry and hard.* 



In the study of galls made by plant-lice, select 

 some common species of gall, so that specimens can 

 be cut open and examined at frequent intervals. 

 Note carefully by this method what goes on within 

 the galls, and observe the spreading of the young 

 from the galls and the formation of new galls. 



* For a thorough study of this subject, see the following : — Alternating 

 Generations : A Biological Study of Oak Galls and Gall-flies. By Her- 

 mann Adler. Translated and edited by Charles R. Straton. Published 

 by Macmillan & Co. Price, $3.25. 



