597 



are dealt with in this paper, the type of injury done by each being 

 discussed. New and little-known kinds of scar have been studied, 

 particularly those caused by the apple redbugs, Lygidea mendax and 

 Heterocordylus malinus. The scars due to other agencies are also 

 briefly dealt with. 



Plaxk (H. K). The Blackhead Fireworm of Cranberry on the Pacific 

 Coast. 



Heinrich (C). Technical Description. — U.S. Dept. Agric, Washing- 

 ton, D.C., Bull. 1032, 25th April 1922, 46 pp., 3 plates, 15 figs. 

 [Received 5th October 1922.] 



In consequence of the severe damage to cranberry bogs on the 

 Pacific Coast by Rhopohota naevana, Hb. {vacciniana, Pack.) (blackhead 

 fireworm), which is the most injurious cranberry pest in that region, 

 a thorough investigation was undertaken during 1918 and 1919, 

 resulting in much additional information being gained regarding the 

 life-history and remedial measures [R.A.E., A, vi, 561 ; ix, 50; x, 55, 

 etc.]. Flooding the bogs, which is one of the most successful measures 

 practised in the Eastern States, is seldom resorted to on the Pacific 

 Coast, and as it is most unusual for any of these bogs to be com- 

 pletely covered with water at any time, and the seasonal temperature 

 is comparatively equable, while the number of parasites is small, 

 every condition enables the pest to become very destructive. The 

 larvae are, in fact, feeding on buds, foliage, blossom and fruit through- 

 out the growing season. There are two full generations in a year 

 and sometimes a partial third. Temperature, densit}^ of vines and 

 drainage are the three most important factors in the hatching and 

 development of this moth. The work of the larvae is shown by the 

 burnt appearance of the vines, hence the name. The pupal stage is 

 passed in a cocoon among old leaves or debris beneath the vines. 

 The moths can be carried several hundred feet on the wind, and the 

 eggs may be disseminated over a bog by means of leaves floating 

 on the water or on leaves and cuttings used in planting. 



Natural enemies include a fungus that destroys many pupae, 

 especially on old and badly infested bogs. Spiders and Coccinellids 

 devour many adults and larvae. Experiments on a large scale proved 

 the most effective spray to be 40 per cent, nicotine sulphate, 1 part to 

 800 parts of water, with 2 lb. fish-oil soap per 50 U.S. gals., using about 

 300 U.S. gals, to the acre. With 1,000 parts of water insteadof 800 

 the results were almost as good. Three applications of either sliould 

 be made. Nicotine oleate, made by mixing 2-J- parts of a solution 

 containing 40 per cent, free nicotine with If parts of commercial 

 oleic acid (or red oil) , using 1 part to 400 parts of water, applied three 

 times at the rate of 300 to 400 U.S. gals, per acre, was also nearly 

 as effective. Lead arsenate proved of little value. Fish-oil soap was 

 a much better spreader than glue for cranberry foliage. Four applica- 

 tions of any of these sprays generally gave better results than three. 

 The first should be made when the new growth is about f in. high, 

 the second when the blossoms are in the early "hook" stage, and the 

 third when the vines are in full bloom. On heavily infested vines a 

 fourth application should be made during the first two weeks of July. 

 The spray can be made with Bordeaux or lime-sulphur solution instead 

 of water, but in that case no soap should be added. A large eddy- 

 chamber type of nozzle, throwing a medium fine mist, at a pressure 

 of about 2001b. at the tank is the best, and does not injure the 

 blossoms. A spray gun should only be used on lightly infested bogs. 



