264 



LEAF-MINING INSECTS 



in New York and Pennsylvania. The eggs are inserted 

 under the lower epidermis and the mines are confined to the 

 lower surface of the leaf. Although the mines may be 

 abundant they are easily overlooked because they are not 

 at all visible from the upper side of the leaf. The mines 

 are shallow, linear, very elongate and often anastomosing 

 considerably to form small blotches or lateral chambers. 

 They are pure white in color, the width of the mine changing 

 very little during its course. The larva transforms at a 

 slightly enlarged chamber at the end of the mine. 



Fig. 84. Mine of Phytomyza lactuca on wild-lettuce. 



The Columbine leaf-miner, Phytomyza aquilegiae, is a 

 common species about Ithaca, New York, and frequently is 

 injurious both in greenhouses and in flower gardens. 



Cory (1916) has some excellent notes on the eggs of this 

 species which we borrow. 



The egg is oblong-oval, slightly longer at one end. It is translucent 

 pale greenish white sub-glossy and bears no surface markings. Length 

 123. X 235 microns. 



The eggs are deposited in the under side of the leaves with the point 

 sometimes directed almost at 90 degrees to the leaf surface and again they 

 may be pushed into the tissues so far that they lie parallel with the leaf 

 surfaces. 



The larvae 3 produce very conspicuous and rather beautiful, 

 long, linear mines. These occur only on the upper side of 



1 The following account has been taken from Frost (1924). 



