218 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



Hewitt, C. G. Ann. Repts. Dom. Ent., Dept. Agric, Canada, 1910-11, pp. 226- 

 227; 1911-12, p. 178. Parliamentary Evidence, pp. 40^1, 1910. Forty-sec- 

 ond Ann. Rept. Ent. Soc. Ont., pp. 63-65, 1911. 



Hinds, W. E. "Contribution to a Monograph of the insects of the order Thysanop- 

 tera inhabitating North America." Proc. U. S. Nat. Mus., Vol. 26, pp. 79-242, 

 11 pis. A striatus, pp. 161-166, pp. 49-51. 1902. 



KoROLiKOFF, S. M. "Tripsi jivoustchie na nacikhstakakh." Isviestiia Moskows- 

 kago Selskhosiaistvennago Instituta. Vol. 16, pp. 192-204. 1910. 



Ormerod, E. a. Text-book of Agric, Entomology, 2nd ed., p. 196. 1892. 



Straviak, F. Deut. Landw. Presse, Vol. 39, p. 771. 1912. 



Taschenberg, E. L. Praktische Insektenkunde, Vol. 4. p. 213. 1880. 



ZiMMERMANN, H. " liber das Massenauftreten namentlich schadigender Insekten- 

 formen." Zeit. Pflanzenkrankheiten, Vol. 21, pp. 257-269. 1911. 



Mr. W. E. Hinds : It is a normal habit of these insects, particularly 

 in the younger stages, to feed on the leaf sheaths or stems. I am sure 

 that Doctor Hewitt's observations on the young actually feeding on 

 oat stems is correct and I do not think there is any doubt of their 

 being capable of causing the trouble mentioned in his paper. 



Mr. C. Gordon Hewitt: There are two types of injury; one where 

 the stem is attacked and another where sterility is produced by the 

 insects actually attacking the ovaries and anthers. 



Mr. W. M. Wheeler: As Doctor Hewitt has said, he has been 

 dealing with a case of parasitic castration. Since the reproductive 

 organs of the oat plant abort through lack of nutriment, we may con- 

 ceive this castration to be brought about either by such insects as 

 thrips or by parasitic plants, such as certain species of moulds. 



Mr. Herbert Osborn: We had a case at the Experiment Station 

 in Iowa many years ago of apple blossoms being attacked by another 

 species of thrips in which the same condition was produced. Sterili- 

 zation of the blossom resulted before the bloom opened. We were 

 unable to find any fungus disease there. 



Mr. C. Gordon Hewitt: This question of sterility was first sent 

 to the Dominion Department of Agriculture with the idea that it was 

 caused by bacteria or fungus. 



President P. J. Parrott: The next paper is by Mr. C. L. Metcalf, 

 entitled "The Egg-Laying Habits of the Pecan Twig Girdler." 



EGG-LAYING HABITS OF THE PECAN TWIG GIRDLER 



By C. L. Metcalf, Raleigh, N. C. 

 (Withdrawn for publication elsewhere) 



Mr. H. T. Fernald: A resident of Massachusetts had a grove of 

 pecan trees in the state of Mississippi and he found that this beetle 



