60 LEAF-MINING INSECTS 



backwardly-directed hooks which serve as an anchorage, 

 and hold in the passage through the cocoon wall. In Erio- 

 crania the structures which accomplish the same ends are 

 chiefly the great mandibles which work back and forth to 

 burst the cocoon and then to dig up through the soil. 



Adults. The adults of leaf-mining caterpillars are nearly 

 all very small. Some members of the genus Nepticula have 

 a wing expanse of hardly 3 mm. (J inch), and the average 

 expanse of wing in the great genus Lithocolletis is between 

 5 and 8 mm. 



But for all their minuteness the "micros" are creatures of 

 exquisite beauty. It is as though having so little area they 

 could be prodigal in decoration of it; they are lavish of 

 silver and gold, of color and design. As Reaumur writing 

 almost two hundred years ago says of them "Nature would 

 have nothing more rich, nothing more brilliant, nothing 

 more beautiful than such moths had they been built on a 

 large scale." Very often the hind wings are very lanceolate 

 with fringes as wide as or wider than the wing. In most, the 

 fore wing is the one on which the color pattern is elaborated. 

 This wing, too, is often very much fringed. In the various 

 families the clothing of the head, the shape and position of 

 the palpi, and antennae, length of the tongue, and especially 

 the venation of the wings varies very much, as may readily 

 be seen from looking over the fine hand-colored plates in 

 Stainton's Natural History of the Tineina, or the line draw- 

 ings in Spuler's Schmetterlinge von Europa; but in this dis- 

 cussion it is with the habits of the larvae rather than the 

 characters of the adults that we are particularly concerned. 



THE MINES 



If individuality is to be found in the forms of these crea- 

 tures in their various stages it is even more apparent in their 

 manner of life. Frequently though the insect itself may not 

 be seen in any stage, chapters of life history written in green 



