220 



FOREST ENTOMOLOOxY. 



The moth (tig. 219) may be described as follows : Fore wings long 

 and narrow, glossy dark -grey, with several wavy black transverse 

 lines. Basal and first lines preceded by a white fascia ; first line very 



distinct on costa ; second 



line angulated and bordered 



on its outer margin with a 



white line ; an indistinct 



shaded grey line between 



it and the hind margin ; a 



pale central spot on disc of 



wing. Hind wings concol- 



orous. Length 22 to 25 mm. 



This species belongs to the 



family of Crambites, and typical moths of the same may be seen ily- 



ing, or rather leaping on the grass fields, in a summer evening walk. 



Fig. 219. 



-Dioryctria abietella (full size). (Drawn by 

 P. J. Browu.) 



Family TORTRICID.E. 



The moths of this family are comparatively small, and some natur- 

 alists have proposed for systematic considerations, as regards external 

 anatomy, to merge it with the Tineidpe. This suggestion, however, 

 has not met with much support, and from an arboreal point of view 

 the two families should be considered as quite distinct. The name 

 Tortricidae refers to the general habit the larvae of those moths possess 

 of rolling up leaves, or twisting and distorting shoots and buds. The 

 mode of rolling leaves by small larvae has been much discussed, and 

 is probably due to definite operations of the larvae, together with 

 assistance derived from silk threads spun by themselves. These silk 

 threads are rolled round the leaves, and they harden and contract 

 from exposure to the air. After the leaf is thus bound by the tiny 

 thread, the roll is still further perfected by the growth of the vege- 

 table organism accruing from the interference of the caterpillar agency 

 acting within the prescribed limits of the silken thread. 



As a great many species of this family are arboreal feeders, a large 

 field for investigation is presented to the student of forest insects. 

 The prospective interest is still further intensified, as their life-history 

 is involved in considerable obscurity, more especially in the egg 

 stage, inasmuch as the moth often effectually conceals her eggs. The 

 injuries are done just when growth is most active, and it is obvious, 



