48 



LEAF-MINING INSECTS 



The females of a few of the most primitive genera are 

 equipped with an ovipositor by means of which they are 

 able to make punctures and to insert their eggs into the 

 leaf tissue. We cite two of the best known examples. 



The egg of Eriocrania semipurpurella is described by 

 J. D. Hood as being cylindrical, twice as long as broad and 

 rounded at the ends at the time of laying. Afterwards the 

 egg swells and comes to fill the pocket in which it is, thus 

 losing its symmetry. He gives the measurements of T. A. 

 Chapman which show the ratio of the cubic contents at the 



Fig. 20 Fig. 21 



Fig. 20. The ovipositor of the moth of the maple casebearer. (From 

 Herrick.) 



Fig. 21. The egg of maple casebearer in pocket on the under side of a 

 leaf. (From Herrick.) 



time of la}dng to the cubic contents on the fourth day 

 thereafter to be as four is to eleven, the length at the time of 

 laying being 0.0141 inch. 



The eggs of the maple case-bearer Paraclemensia aceri- 

 foliella and the manner of their deposition are described 

 and illustrated by Professor G. W. Herrick as follows: 



The female moth deposits her eggs in tiny pear-shaped pockets 

 in the tissues of the leaf just beneath the lower epidermis. The 

 female has a complicated extrusile ovipositor. There are four 



