SUPERFAMILY TINEOIDEA 115 



goes its first moult within the leaf and Miss Braun's state- 

 ment that B. crescentella, which makes trumpet-shaped mines 

 marked with a central line of frass in leaves of various com- 

 posites, does no external feeding. On the other hand, we 

 lack any definite information that B. canadensisella, the birch 

 leaf skeletonizer, is a miner at any stage and this despite 

 repeated notice in connection with conspicuously severe 

 outbreaks in northeastern North America. Probably it 

 resembles related species and mines in the first instar but 

 of the scores who have observed its moulting and pupating 

 cocoons and the effect of its external feeding on the leaves, 

 the late James Fletcher alone makes any statement of ob- 

 serving mines in the leaves. He found small mines which 

 he supposed had been made by the caterpillars in their first 

 stage but he did not actually find larvae of B. canadensisella 

 in the mines. Neither he nor any other observer record 

 observation of the eggs. From the time of spinning its 

 first moulting cocoon on the leaves it resembles the ribbed 

 cocoon maker of the apple in habits. 



GRACILARIIDAE 



This is the great family of leaf -miners. Within it are en- 

 rolled about as many species as of all the other lepidopterous 

 miners taken together. In numbers of individuals they are 

 dominant in whatever places of the earth the leaf-mining 

 habit has been particularly observed. The family seems 

 to be cosmopolitan in distribution. The species have been 

 studied particularly in Europe and North America, but there 

 are scattering life-histories published from India, Japan, 

 Hawaii and elsewhere. 



Yet despite the countless millions of these little larvae, 

 taking each its tiny portion of the herbage of the world, but 

 few indeed of the species are accounted as pests. Not only 

 does their minute size partially excuse them, but in feeding 

 habits most of them are very precise and economical of 



