GENERAL 



15 



through which they thrust out all their frass, keeping the 

 interior clean and white. Most mines are closed. Those of 

 the Buprestid beetles have the hole through which the larva 

 enters capped with the empty egg shell glued down so securely 

 that it remains in place through the season. 



Those unspecialized leaf -mining larvae that wander from 

 leaf to leaf making new mines as they choose, must needs 

 make an opening when they enter; but it is often no more 

 than a slit through the epidermis, and the edges of the slit 



L0W2R SUBFACELi 

 MINE 



Fig. 8. Diagrams of cross sections of three leaf mines that differ as to 

 depth. 



close behind them. The common mode of entrance for all 

 the better leaf -miners is through the attached surface of the 

 egg, leaving no hole for unwelcome bacteria and spores to 

 enter. 



4. As to distribution, mines often take a definite position 

 or course on the leaf surface, along the margin or along the 

 midrib, originating at the edge and proceeding inward or 

 following between parallel veins (see fig. 11). They may 

 be greatly elaborated, they may take a more or less regular 

 appearance and become star-like or linear mines may curve 

 upon themselves in concentric arcs (see fig. 18). Their 



