98 



tion consisted entirely of small trees and these were seriously affected. 

 Examination of trees on neighboring farms showed that frequently as 

 much as 50-^- per cent of the leaves were atfected and that those j^lants 

 groAving in the shade, or very close together, were more seriously 

 affected than tliose in the open. However, the small trees upon the 

 experiment station farm were suffering more than the large trees 

 upon the neighboring farms. 



LIFE HISTORY. 



The adult insect is about 2.5 millimeters in length and of a silver- 

 gray color, tipped with black on the posterior end. When not in 

 flight the AA'ings are folded close to the body. The length of life in 

 the adult stage is probably not more than forty-eight hours, and it is 

 improbable that the insect travels to any great distance, unless carried 

 by air currents. Within twenty- four hours after emerging from the 

 pupa the female insect punctures the upper surface of the young leaf 

 and deposits her eggs. In fact the adults usually emerge from the 

 pupa during the night and deposit their eggs during the following 

 night. It is possible with the unaided eye to see the small slits in the 

 leaves, and they are clearly visible with the aid of a small hand lens. 

 Within four or five days small black sjiots surrounding the punctures 

 make them clearly visible to the unaided eye and indicate that the 

 eggs have hatched and that the larva? are working within the meso- 

 phyll of the leaf. The larva lives within the mesophyll of the leaf 

 for about three weeks, causing large, black, irregular spots, w^hich indi- 

 cate the area through which the mesophyll has been destroyed. Fre- 

 quently the punctures are so close together that the galleries become 

 united into one very large area. In some cases every leaf on a plant 

 is affected and many of them are entirely destroyed. Young trees 

 are often entirely defoliated. 



After about three weeks within the leaf, the larvse cut their Avay out 

 through the upper epidermis and in a very short time seek a protected 

 place on the under surface of the leaf and pupate. The larvae are 8 

 to 4 millimeters in length, and in pupating first weave a delicate web 

 in the form of a letter H with a very broad crossbar. Between this 

 Aveb and the surface of the leaf the small pupa is formed. The web 

 and the pupa are very delicate and are so placed on the under surface 

 of the leaf that they are protected from the excessive rains of the 

 rainy season. Within three to seven days the adult moth comes from 

 the pupa, and the life cycle is complete. 



TREATMENT. 



The location of the larva within the leaf makes any treatment at 

 this stage practically impossible. However, the delicate character 

 of the pupa furnishes a vital point for attack, and experiments were 



