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Severin (H. II. P.), Severin (II. C.) & IIartung (W. J.). The 

 Ravages, Life-History, Weights of Stages, Natural Enemies and 

 Methods of Control of the Melon Fiy {Dacus cucurbUae, Coq.) — 

 Aim. Entom. Soc. Amer., Columbus, Ohio, vii, no. 3, September 

 1914, pp. 178-207, 6 plates, 4 figs., 11 tables. 



Dacus cucurbitae, Coq., the most destructive pest of the Cucur- 

 bitaceae in the Hawaiian Islands, is responsible for a loss there of 

 nearly a million dollars annually. The native home of this fly is not 

 known, but it was imported into the Hawaiian Islands about 1897, 

 since when it has rapidly increased. The eggs are laid on the more 

 tender parts of the plant and the larvae devour the tissue of the tender 

 stems and then penetrate the roots, destroying entire plants. The 

 old stems and roots of pumpkins are also often infested with the larva 

 of a Cerambycid, Apomecyna neglecla, Paso., {-pertigera, Thoms.). The 

 larvae of D. cucurbitae also devour the seeds and fleshy parts of the 

 pods of string beans, and this species has been bred from numerous 

 cucurbitaceous vegetables, besides mango, orange, and papaw. An 

 average of 31 flies were reared on single staminate flowers, including 

 the long peduncles, and from 183 to 637 were reared on single pumpkins, 

 from 2|to4 inches long. The average egg stage was found to be Ijto 

 \\ days, the larval 3| to 11 days, and the pupal 10 to 14 days. Ex- 

 periments show that egg-laying begins 14 to 17 days after the adults 

 emerge, and the complete life-cycle thus varies from 29 to 43 days. 

 There are probably from 8 to 12 generations a year. The flies usually 

 feed during the early morning, and were frequently found feeding on 

 the flowers of glue bushes, sunflowers and Chinese bananas, never on 

 pumpldn flowers, though frequently on the juices of injured or in- 

 fested plants. The dragon fly, Pantala flavescens, F., is believed to 

 prey upon these flies, but examinations of their alimentary canals 

 showed no signs of this ; the Reduviid, Zelus peregrinus, Kirk., and 

 perhaps Staphylinids are predaceous on them. The Chalcid, 

 Spalangia hirta, Hal., was bred from puparia of the melon fly, 

 three parasites emerging from 500. Burying infested cucurbi- 

 taceous plants is a commonly recommended method of control, 

 but experiments show that a covering of less than 3 feet of 

 soil is useless, though lime would probably destroy the larvae if 

 buried in sufficient quantity with the plants, but would increase 

 the cost. Experiments on the effects of submergence on the 

 larvae show that if infested vegetables be submerged in a tank of 

 water for four days, and then ploughed in, the insects are destroyed 

 and a valuable fertiliser is added to the soil. Screening is not practic- 

 able, because the screens keep out not only the flies but also those 

 insects which fertilise the flowers ; cantaloupes when set among 

 cucumbers as trap crops, failed to protect them. When a Japanese 

 fly-trap, similar to the American glass-trap, with molasses as a bait, 

 was wired in an orange tree, in 12 days, 19 male and 58 female Mediter- 

 ranean fruit-flies, 3 male and 1 female melon flies were drowned in 

 the soapy water, but 2 American glass fly-traps, when set in a pumpkin 

 patch, caught no Trypetids ; twelve common mosquito-screen fly-traps 

 were equally unsuccessful. Herrick's moth trap and other night traps 

 failed to attract any melon flies. The effectiveness of the poisoned 

 bait spray, already used against Dacus oleae, Rossi, Ceraiitis capitata, 



