74 LEAF-MINING INSECTS 



European microlepidopterists before him, judged the larva 

 to be coleopterous and so gave it scant attention. He did, 

 however, take some notice of its behavior. He says that it 

 mined in half circles of about 10 mm. diameter using the 

 point of the anal segments as a pivot on which to swing, 

 that it ate rapidly, and wriggled about very much if dis- 

 turbed. The mines occupied sometimes the whole end of a 

 leaf or half of one side of the midrib. 



About the first of June he put some of the leaves in a 

 container with some soil and a bit of moss and noticed that 

 in a few days the larvae left the leaves and went into the 

 soil. Afterwards reading in Stainton's Natural History 

 of the Tineina he found a clue to their real identity and, 

 returning with some avidity to the container, he found in the 

 soil the tough typical cocoons and within them some dried up 

 larvae and pupae but some living pupae also. These last he 

 was able to identify with certainty by a comparison with 

 Packard's figure of Eriocrania purpurella of Europe. He 

 was, however, unable to breed the perfect insect and so to 

 state with certainty its species. This Busck accomplished 

 later. 



The period of mining is very short. According to Busck 

 and Boving the larva of E. auricyanea is full-grown about ten 

 days after the hatching of the egg. It then cuts a small 

 semicircular slit in the upper epidermis of the leaf and leaves 

 the mine, dropping to the ground, where it at once digs down 

 until it finds a suitable place in which to make its cocoon. 

 Normally this is attained within a few inches or even less 

 from the surface of the ground, often next to a stone, and 

 there are records of depths as great as 8-10 inches. There 

 the larva bends itself into a circle and pushes the soil aside 

 to make a small firm cell in which it then spins its very strong 

 oval cocoon. 



The cocoon is so tight fitting around the larva and is made 

 of so closely woven tough silk that it is difficult to cut it 



