24 DECIDUOUS FEUIT INSECTS AND INSECTICIDES. 



l^aper on the Tineidse infesting the apple trees at Ithaca, N. Y., 

 gives an account of the insect with figures of moth, larva, and mines 

 in apple leaf. A more extended account is given by Dr. C. M. Weed 

 in the Fifteenth Report of the Illinois State Entomologist (1889). 

 pages 45-50; and it is mentioned by Lugger in Minnesota Experiment 

 Station Bulletin 61 (1898), page 31G, and later (1903), by Wash- 

 burn, in ]\Iinnesota Bulletin 84, page G6. In Bulletin 180 of the 

 Michigan Experiment Station (1900), page 125, and Special Bulletin 

 24 of the same institution (1904), page 22, the species is the subject 

 of short illustrated articles by Pettit ; and it is also discussed by 

 Lowe in Bulletin No. 180 of the New^ York Agricultural Experiment 

 Station (1900), page 134. In 1906 brief mention is made by C. P. 

 Close of the occurrence of this species in central Delaware (Bui. 73, 

 DehiAvare College Agric. Exp. Station, p. 18), where it is said to have 

 been increasing for several years past. 



The above includes the important references to this species so far 

 as the Avriter has been able to determine." 



DESCRIPTIVE. 



The mine. — Tlie mines occur exclusively on the upper surface of 

 leaves, beginning at the point of deposition of the egg as a narrow, 

 often curved line, gradually or suddenly enlarging in isolated and 

 typical examples, and finally having the outline of a trumpet or 

 mussel shell (see PL V). Completed mines vary much in shape and 

 size, but will average, perhaps, in the more typical examples one-half 

 inch long by one-fourth inch wide. There is considerable irregu- 

 larit}^ in the feeding habits of the larva?, and blotch mines are often 

 produced, the narroW' linear portion being frequently more or less 

 obliterated. In many mines crescent-shaped patches of white cross 

 the linear portion, extending often Avell into the body of the mine. 

 Unless held to the light the mine is scarcely noticeable from the low^er 

 surface of apple leaf, but above the blistered epidermis varies in 

 color from whitish to dark brown, and the spotted appearance of 

 badly infested leaves is noticeable some distance from the trees. 

 Injury is confined principally to the palisade layer of cells immedi- 

 ately below the epidermis of the upper surface of the leaf. The posi- 

 tion of the mine on the leaf is quite variable, but it does not usually 

 cross the larger veinlets, extending more or less parallel with them. 



The egg. — The eggs of Tischeria malifoliella are regularly ellip- 

 tical in outline, somewhat convex centrally, but flattened around the 

 margin, which area is more or less wrinkled. When first laid they 



n Since this article was prepared this species has been well treated by Mr. 

 ('. I). .Jarvis, in Bulletin 45 of the Storrs, Connecticut, agricultural experiment 

 station. 



