GENERAL 



33 



the species, of both the host plant and the insect mining 

 the leaf. A thin sheet of celluloid may be placed over each 

 of the mounts. Most of the herbarium specimens show very 

 clearly the arrangement of the frass within the mines, the 

 exit holes of the larvae, and other characters of interest. 

 Photographs have the advantage of being more durable 

 than the herbarium records, but they are far from being 

 as accurate and as rich in minute details. 



Fig. 16. Diagram illustrating head form in two orders of leaf -mining 

 larvae. A, a sawfly larva (Hymenoptera) ; B, a beetle larva (Coleoptera). 



How to identify leaf-miners. First collect them, and get 

 the name of the plant on which you find them. Then look 

 in the list on page 302 to see what insects are known as 

 miners in the leaves of that species of plant and of others 

 near akin to it; that is, in members of the same plant family. 

 Among these you may find your specimens described; so 

 note carefully the form and depth and spread of the mine, 

 the presence and distribution or absence of holes, silk and 

 frass, and the form and structure of the larva within it. 

 The table on page 35 may then be used to determine the 



