24 DECIDUOUS FRUIT , INSECTS AND INSECTICIDES. 



paper on the Tineida' infesting the apple trees at Ithaca, X. Y., 

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

 in apple leaf. A more extended account is given bv 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 Gl (1898), page :3ir.,\uid later (1903), by Wash- 

 burn, in INIinnesota Bulletin 84, page GG. In Bulletin 180 of the 

 Michigan Experiment Station (1900), page 1:25, and Special Bulletin 

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

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

 Lowe in Bulletin No. 180 of the Xew York Agricultural Experiment 

 Station (1900), page 134. In 190G brief mention is made by C. P. 

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

 Delaware 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 writer has been able to determine." 



DESCRIPTIVE. 



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

 leaves, beginning at the point of deposition of the Qgg 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 PI. V). Completed mines var^^ much in shape and 

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

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

 larity in the feeding habits of the larvcT, and l)lotch mines are often 

 l)roduced, the narrow linear portion being frequently more or less 

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

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

 Unless held to the light the mine is scarcely noticeable from the lower 

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

 color from whitish to dark l)rown, 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 vcink^s, extending more or less parallel with them. 



Tlie e(/</. — The eggs of Tischeria maJifoJielht are regularly elli})- 

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

 uiargin, which area is more or less wrinkled. AVhen first laid thev 



" Since this .ii'ticlo was preparefl this species has liooii well treated by Mr. 

 ('. I >. .Inivis, in I'.uilotin 4.^» of the Storrs, Connecticut, atxri cultural experiment 



station. 



