15 



There has been much conjecture as to the part played by the 

 bast miner, Ectoedemia pJileophaga. an insect which is very 

 abundant on the chestnut. The adult of this insect is an ex- 

 tremely small Micro-Lepidopterous form which, judging from 

 its life history, cannot in our opinion cause new infections 

 directly. It is of great importance, however, from the fact that 

 the large number of openings which this form makes in the 

 bark of the chestnut serve as points in which new infections 

 may start from spores introduced by other means than by the 

 Dast miner. 



METHOD. 



The authors wish to express their appreciation for the 

 many helpful suggestions and criticism of Dr. F. D. Heald, 

 under whose supervision the work was carried out. Credit 

 is also due to Prof. W. M. Wheeler of Harvard University for 

 the determination of all the ants herein reported. 



The insects used in these tests were for the most part col- 

 lected in the field, but some of them were ants used in certain 

 laboratory and insectary tests. Those brought in from the 

 field were collected at four different points in Pennsylvania, — 

 West Chester, Valley Forge, Lehighton^ and Fairmount Park, 

 Philadelphia. All but three of these insects (Nos. 69-71) were 

 picked directly from chestnut blight cankers with sterile 

 forceps, and dropped into sterile tubes plugged with cotton. 

 In some instances use was made of cyanide tubes, also plugged 

 with cotton and sterilized in the autoclave. It had been pre- 

 viously determined that the potassium cyanide has no appre- 

 ciable effect on spores of the blight fungus (16). 



When brought to the laboratory each insect was dropped into 

 a flask containing 100 cc. of sterile tap water. The flask was 

 shaken at intervals and the insects were always permitted to 

 remain in the water for at least several hours before the plate 

 cultures were made, or, in many instances in which they were 

 brought to the laboratory in the late afternoon or evening, 

 they were kept in the flasks all night, thus affording sufficient 

 opportunity for the spores to become loosened from their feet 

 and body. By means of a sterile pipette small quantities 



