144 LEAF-MINING INSECTS 



The adult. They are plain little moths, whose wing 

 markings are limited to dustings of lighter and darker 

 scales. In expanse of wings they measure usually less than 

 half an inch. 



This genus has considerable economic importance. The 

 destructiveness of the group would be much less were it 

 not that all the larvae hibernate in a late stage of develop- 

 ment and in very early spring are ready to do their most 

 destructive feeding just as the host plants are beginning to 

 put forth leaves. At this season those attached to fruit 

 trees, for instance, burrow into leaf and fruit buds or into 

 succulent young growing twigs and in this way cause con- 

 siderable injury. Fortunately, they are of very small size, 



Fig. 46. The work of the larch base-bearer, Coleophora laricella. (After 

 Herrick.) 



have but one generation a year in most cases, and, despite 

 their protective coverings, are attacked by various hymen- 

 opterous parasites, by predacious insects and by birds. In 

 orchards, where artificial measures are practicable, arseni- 

 cal sprays applied to the foliage or lime-sulphur wash 

 applied before the buds expand diminish their numbers very 

 greatly. 



The larch case-bearer, coleophora laricella, now very com- 

 mon in the eastern parts of the United States and Canada, 

 has been imported from Europe where it is apparently 

 native. It was doubtless introduced here with the Eur- 

 pean larch. Larix europea, but it has spread to our com- 

 mon native, Larix americana. On this continent it was 

 first reported in 1886 from Massachusetts by Dr. Hagen. 

 Now it is found from the Atlantic seaboard inland at least 



