215 



when the wind velocity is over 20 miles an hour, the flies cling to the 

 plants in the infested fields and are not wind-borne to any extent. 

 These observations show that co5peration must be practised over 

 large areas and that the individual grower camiot secure immunity 

 from injury merely by the preparation of a good seed-bed and late 

 planting. All stubble and self-sown Avheat must be ploughed under 

 in early autumn, as these are the greatest sources of infestation. 



Collins (C. W.). Methods used in determining Wind Dispersion of 

 the Gipsy Moth and some other Insects. — Jl. Econ. Entom., 

 Concord, N.H., x, no. 1, February 1917, pp. 170-177, 2 plates. 



Additional data to those previously obtained [see this Review, Ser. 

 A, in, p. 710] have been collected on long distance wind dispersion of 

 the larvae of the gipsy moth [Lymantria dispar] and these are given in 

 the form of a table. The direction of the wind, recorded both at the 

 time the larvae were taken and previously, indicated the source of 

 infestation to be 19 to 30 miles distant. Besides gipsy moth larvae, 

 other Lepidopterous insects were taken on the screens. These in- 

 cluded a first stage larva of Hemerocampa leneostigma, S. & A., 

 probably carried two-thirds of a mile at a wind velocity of 4 to 5 miles 

 an hour. Specimens of a Noctuid and of a Geometrid were taken, 

 but were too badly injured by removal from the tanglefoot to be 

 specifically identified ; their capture suggests possibiHties for investi- 

 gation with other species on these lines. 



Grossman (S. S.). Some Methods of colonizing imported Parasites and 

 determining their Increase and Spread. — Jl. Econ. Entom., 

 Concord, N.H., x, no. 1, February 1917, pp. 177-183, 1 fig. 



This paper describes the methods of colonising the Encyrtids, 

 Anastatus bijasciatus, Fonsc, and Schedius kuvanae. How., against 

 the gipsy moth [Lymantria dispar]. S. kuvanae hibernates in the 

 adult stage and begins to oviposit in gipsy moth eggs a week or two 

 before these begin to hatch in the spring, the eggs constituting the 

 host of the parasite until the summer. As soon as the gipsy moth 

 eggs are laid in July, they are attacked by this parasite, which pro- 

 duces a fresh generation about every 25 days, imtil hibernation takes 

 place, four generations and a partial fifth being completed each autunm. 



A. bifasciatus, which has only one generation, oviposits in newly 

 laid gipsy moth eggs, the larvae devouring the egg contents and 

 remaining within the host throughout the winter and early summer, 

 pupating and reaching the adult stage in time to attack the newly 

 laid eggs of the next season. As there is thus only one generation 

 per annum, the dispersion of A. bifasciatus is much slower than that 

 of *S. kuvanae. 



Material for colonising S. kuvanae is obtained by breeding at the 

 laboratory in gipsy moth eggs, spread over the bottom of trays. 

 AVhen a new generation of the parasite issues from these eggs, the 

 trays are darkened above and holes are bored in the side into which 

 are inserted paper cones which hold glass tubes. By placing electric 

 lights in front of the tubes, a number of the parasites are induced to 

 enter them ; these tubes are then closed, a piece of paper smeared 



