INSECTS AFFECTING PARK AND WOODLAND TREES I71 



and continue their feeding. Stainton observes that at tliis time tiie 

 previously formed case is too small, and as the diameter of the larch \v3.( 

 is limited, the larva is forced to slit down its old case and add thereto a 

 piece of mined leaf, thus affording- necessary space. He also states that 

 there is but a single generation, and this accords with our observations. 



Description. Tiie adult insect can be recognized by reference to plate 

 18, figure 9. It will be seen that it is a modest, gray moth with no very 

 distinctive markings. 



The caterpillar is brown with the head, thoracic shield, small spots on 

 the dorsum and the anal plate black [pi. i8, fig. 7]. The characteristic 

 appearance of a mined leaf, illustrating also the hole through which tlie 

 larva feeds, is shown at plate 18, figure 5. 



The case resembles somewhat that of our cigar case bearer, C o 1 e o- 

 p h o r a f 1 e t c h e r e 1 1 a Fern., being straight and nearly cylindric, though 

 close observation will disclose the ridges caused by the edges of the leaves 

 used in its construction. It is usually a light grayish color with the head 

 end obliquely truncate. 



Distribution. This species is widely distributed, according to Stainton, 

 who lists it from a number of English and Scottish localities, and states that 

 it occurs throughout Germany and has been observed in P'inland, Switzer- 

 land and France. Professor Meyrick states that the larch is not indigenous 

 to Great Britain, and that this insect must have been introduced with its 

 food plant. 



Remedial measures. The larch being frequently used as an ornamental 

 tree, is sometimes quite valuable, and wherever this miner becomes abnor- 

 mall\- abundant, it can probalily be controlled by thorough spraying in 

 early spring with an arsenical poison. This has been found very effective 

 in the case of allied case bearers affecting fruit trees. We suggest that 

 arsenate of lead be used, and that the application be made as soon as the 

 young leaves begin to appear, so as to poison the over-wintering caterpillars 

 before much feeding occurs. Otherwise, it will be almost impossible to 

 destroy the insects, since they do so much of their feeding within the leaf. 



