36 



Severin (H. H. p.). a review of the work on the poisoned bait spray; 

 dry method and mixed treatment of controlling fruit-flies [Tryjpe- 

 tidae). — Canadian Entomologist, London, Ont., xlvi, nos. 7, 8 & 9, 

 July, August & September; pp. 243-246, 277-284 & 309-314, 

 3 figs., 8 tables. 



This paper reviews the work of the South African, French, Mexican, 

 United States and Canadian entomologists on various fruit-flies, 

 leaving that of Italian entomologists for a future paper. The interval 

 of ten days between emergence from the pupa and the commencement 

 of the egg-laying period is spent by the fruit-fiies in feeding on the 

 nectar of flowers, waxy coating of fruit, juices of injured or cracked 

 fruit hanging on the trees, windfalls, fallen infested fruit, and droplets 

 of water. It is therefore clear why poisonous, sweet substances are 

 so effective in control, especially if available when the flies first 

 appear, as they will then be killed before oviposition. 



The work of Mally, Dewar, Fuller and Lounsbury [see this 

 Review, Ser. A, i, pp. 195-196] with poisoned molasses to control the 

 Mediterranean fruit-fly, Ceratitis capitata, Wied., in South Africa 

 is reviewed. In the Hawaiian Islands, good results from the use of 

 the poisoned bait spray were obtained, despite unfavourable weather 

 conditions ; except that the amount of lead arsenate was increased 

 from 3 to 5 ounces, Mally 's 1909 formula was used (2| lb. brown 

 sugar ; 4 gallons water). To check the effectiveness of the fruit- 

 fly remedy, kerosene traps [see this Review, Ser. A, i, p. 517 ; ii, p. 578] 

 were employed, but after five weekly applications of the bait, a 

 thorough search was necessary to find an infested fruit in the orchard, 

 whereas before spraying almost every ripe fruit had been attacked. 

 In 1910, H. 0. Marsh tested the poisoned bait spray to control the 

 melon fly or bitter gourd fruit-fly, Dacns cvcurbitae, Coq., in the Hawaiian 

 Islands. His baits were poisoned with I oz. of either Paris green or 

 arsenate of lead, added to a solution of 1 quart of molasses and 1| 

 gallons of water ; neither proved effective, flies being frequently 

 observed feeding on the poisoned liquids, but they evidently did not 

 relish them, and so failed to consume a fatal dose. Fuller, in Natal, 

 found that where the poisoned bait spray has been applied for the melon 

 fly, it has proved successful. The author details his attempt to control 

 the melon fly in Hawaii, the same formula as that used to control 

 C. capitata being adopted, except that 1 ounce of a soluble poison, 

 such as potassium arsenate or sodium arsenite, was added to the 

 solution ; but whether the pest, which has been allowed to increase 

 unmolested during the past sixteen years, can be controlled under 

 Hawaiian conditions, when one planter sprays and his neighbours do 

 not, is doubtful. In all probability, better results could be obtained 

 with the poisoned bait spray in a well-isolated cucurbit field away 

 from the valleys, where rains are less frequent during the summer 

 months. 



Against Dacus oleae, the effectiveness of the De Cillis formula was 

 confirmed by French experimenters, but as the cost of some of the 

 materials was rather high, a more economical spray was suggested 

 by Berlese, who discovered that it was better to double the number 

 of apphcations, the cost of six sprayings being only 2d. per tree. It 

 has always been regarded as a matter of extreme importance that the 



