508 



a gall ; both leaf and flower-buds are infested, the mites being found 

 in all stages within the flowers, which they discolour and cause to die 

 jDrematurely. The various stages in the life-history of the mite are 

 described and illustrated. The eggs are laid in masses in moist, dark 

 places provided by the curling and distortion of the leaves, the average 

 duration of the egg-stage being 11 days. The larvae are active for 

 about 7 days, after which they enter on a quiescent stage for 3 or 4 

 days. All stages of the insect may be found on the plants from 

 November until late spring and probably the adults occur in green- 

 houses throughout the year, though it is impossible to determine the 

 number of generations a year owing to the broods overlapping. During 

 autumn and winter, when the greatest damage occurs, the females 

 are more numerous than males. 



As the mites possess an extremely primitive respiratory system, it 

 is difiicult to control them satisfactorily by fumigation with various 

 gases. When older cyclamen plants become badly infested, it is 

 almost impossible to save them, and they should be burnt and the soil 

 sterilised. A much better plan is to carry out preventive measures 

 while the plants are young. Black-leaf 40 has been used successfully 

 and safely on cyclamen, chrysanthemum and snapdragon plants, at 

 the rate of 1 : 1,000 with the addition of a small quantity of soap. This 

 should be first applied when the plants are transplanted, having grown 

 about 1 to l|in. high, and the treatment should be repeated at ten-day 

 intervals until the flower-buds begin to show colour [see this Review, 

 Ser. A, V, p. 264]. Older plants may be dipped in an oil emulsion 

 called Yel-ros, which contains a good deal of xylol, but this is too 

 severe for young plants and results in scorching. The mites usually 

 attack cyclamen first in dry weather, and poor cultivation, insufficient 

 ventilation and moisture encourage their attack. 



IsLEY (D.). Control of the Grape-Berry Moth in the Erie-Chautauqua 

 Grape Belt. — U.S. Dept. Agric, Washington, D.C., Bull. no. 550, 

 9th August 1917, 42 pp., 6 plates. 



The greater part of the subject matter of this bulletin on Polychrosis 

 viteana has already been noticed [see this Review, Ser. A, i, pp. 112-114, 

 and iv, p. 190]. In discussing the usual measures for reducing 

 infestation, stress is laid on the choice of a suitable adhesive in 

 spraying. Experiment has shown resin fish-oil soap to be the best, 

 but failing this, any yellow resin soap can be used, though not white 

 laundry soap without resin, as it lacks adhesive qualities. The most 

 satisfactory spraying mixture has been found to consist of arsenate of 

 lead paste, 3 lb., or powder, \\ lb., resin fish-oil soap, 1 lb., Bordeaux 

 mixture containing copper sulphate, 3 lb. and lime, 3 lb., and water, 

 50 U.S. gals. This is best applied by " trailers," and should be used 

 twice, immediately after the falling of the grape blossoms, and again, 

 two or three weeks later, when the grape berries are just touching. 

 The use of Bordeaux mixture is recommended to prevent the 

 scorching of the foliage by the combination of lead arsenate and soap, 

 as well as on account of its fungicidal action. Spraying operations are 

 greatly facilitated by training the vines so that the clusters can be 

 quickly reached and covered with spray, for unless this is done, the 

 work is of little value, 



