239 



limited to the Island, where its destructiveness varies from 10 per 

 cent, to 50 per cent, of the crop. The flies begin to appear at the end 

 of June, reach their maximum emergence during July, and diminish 

 towards the end of August, being occasionally found as late as October. 

 The duration of adult life is about one month ; the flies are usually 

 found in shady, thickly wooded places, so that orchards of young 

 trees or those exposed to strong wind are generally free from attack, 

 and they do not travel far from their place of emergence. Oviposition 

 occurs in August, eggs being laid under the rind. Thick-skinned 

 oranges are seldom attacked, as the ovipositor is not long enough 

 to reach the pulp. A single puncture is usually made in each fruit, 

 and though there are frequently from 2 to 6 eggs in each puncture, 

 only one larva emerges from each. The period of incubation was 

 not determined, but in one case observed hatching did not occur 

 until the 8th day after oviposition. Larvae appear about the beginning 

 of October and devour the contents of one carpel after another, from 

 2 to 10 carpels being infested by a single maggot. By the beginning 

 of November the larvae are mature and about this time the infested 

 fruit falls. Within a few hours the larva issues from the orange and 

 enters the ground for pupation. Occasionally the larva leaves the 

 orange while it is still on the tree. The resistance of the larvae to 

 both sea and fresh water is very marked ; five days' submergence 

 in water prevents the pupation and emergence of adults to a certain 

 extent ; after 10 days submergence in sea-water or over 24 days in 

 well-water the maggots apparently do not survive. Pupation occurs 

 at a depth of 1 to 2 inches in the soil and lasts from the end of 

 November to the end of December or January. Burying the pupae 

 to a depth of 1^ ft. in the soil did not kill them. 



No definite parasites of D. Isuneonis have yet been found ; dragon- 

 flies and Asilids are probably predaceous on it. Preventive measures 

 in infested localities include capturing the adult flies, collecting and 

 treating infested fruit to kill the larvae, and gathering the pupae. 

 It is recommended that adults should be captured and infested fruit 

 picked up as quickly as possible. Infested oranges should be used 

 as raw material for the preparation of citric acid and the construction 

 of storehouses for oranges should be improved. 



Descriptions are also given of the following new fruit- flies from 

 various localities in Japan : — Dacus {Chaetodaciis) hezzii, abundant in 

 orange-orchards from July to September but not yet found to do 

 any injury to the fruit, Hypenidium polyfasciatum, Acidia kago- 

 shimensis, A. marumoi taken at an elevation of 5,000 ft. , and Gaslrozona 

 japonica. 



NisHiKAWA (I.). Kasan no Gaichu ni Kuwansuru Kenkyu-tsuzuki. 



(Studies rn Insect Enemies of the Si kwcrm, continued.) — Sangyo 

 Shmipo {Journal of the Silk Industry), Tokyo, xxvii, no. 312, 

 1st March 1919, pp. 244-251. 



The additional insect enemies of silkworms here recorded [see this 

 Review, Ser. A, vii, p. 99] are : — The Carabid beetle, Chlaenius pictUs, 

 Chaud., the larva of which occurs in July and August on mulberry 

 foliage infested with the caterpillars of Glyphodes pyloalis, Wlk., 

 on which they feed. When mature, they pupate in the soil at a depth 

 of 1-2 inches in the latter part of August. The adults appear at th^ 



