191 



would seem that they should be directed against the overwintering" 

 pupae [cf. R. A.E., A, viii, 403]. P. viteana does not occur iis a rule 

 in uniform abundance in vineyards, the areas of infestation depending 

 entirely on the existence in the immediate vicinity of conditions 

 suitable for the hibernation of the pupae, such as dry grape leaves. 

 As the flight of the moths is limited, the same areas are reinfested 

 from the same source each year. The worst infestations are generally 

 caused by a combination of depressions and stretches of abandoned 

 or uncultivated land containing a growth of sumac, bush or heavy 

 weeds, or a generally wooded area. As long as the woodland adjoins 

 the vineyard, it apparently does not make much difference in which 

 direction it is, although the infestation seems heavier with such an 

 area to the west or north-west. Satisfactory results have been 

 obtained by burning over and clearing waste places, etc. Where 

 trees or vegetation are left as protective windbreaks, spraying will 

 have to be continued, but great emphasis should be placed on cultural 

 and clean farming methods in dealing with this pest. 



Parks (T. H.). The Effect of Time of Sowing upon the Control of 

 the Wheat Sheath Worm {Harmolita vaginicoliim, Doane). — 

 //. Econ. Ent., Geneva, N.Y., xiv, no. 6, December 1921, 

 pp. 490-492. 



Observations made in 1918 show that the time of sowing has a 

 great deal to do with the degree of infestation of wheat by Harmolita 

 vaginicola, Doane ; all wheat sown after 1st October was severely 

 injured, especially spring wheat. This Chalcid is probably generally 

 distributed over the eastern half of Ohio, the greatest injury occurring 

 in the north-eastern section. In this part of the State, at least, sowing 

 should not be later than 1st October. These dates do not necessarily 

 interfere with the control of the Hessian fly [Mayetiola destructor, 

 Say], as the fly-free dates begin about 23rd September for this section 

 of Ohio. 



HoRSFALL (J. L.). Sources of Infestation of Thrips tabaci in Iowa. 

 — //. Econ. Ent., Geneva, N.Y., xiv, no. 6, December 1921, 

 pp. 493-496, ] fig. 



Thrips tabaci, Lind. (onion thrips) will establish itself and begin 

 breeding on set onions about two to three weeks earlier than 

 on seed onions, thus allowing the possibility of an earlier gener- 

 ation. Set onions in the vicinity of seed onions always prove 

 a source of infestation, so much so that it is doubtful whether 

 the larger returns realised from the early crop compensate for 

 this damage. Hibernation frequently occurs in lucerne fields, and, 

 when the lucerne is cut, the thrips migrate to the onions. During 

 recent observations it was noticed that an adjacent maize field 

 did not serve as an obstruction to the spread of this thrips as 

 has often been supposed. In spite of the application of nicotine 

 sulphate in 1919, the harvested crop from a field of seed onions repre- 

 sented a loss of 75 per cent, over that of the previous year. Adults 

 of T. tabaci were found on lucerne blossoms on 30th July after the 

 onions were harvested, but whether they will continue to hibernate 

 in this field, and thus threaten the onion crop in the future, cannot 

 yet be determined. In one field the infestation was derived from 



