449 



the plant is immune from attack, eggs being deposited on all portions 

 of the plant and fruit. The larvae usually burrow to the centre of the 

 plant or fruit, the place where they feed being largely dependent on 

 the moisture content of the host. In young seedlings they may 

 burrow into the root and kill the plant. It is estimated that this fly 

 causes a loss of about 750,000 dollars in the Hawaiian Islands alone. 



The present paper, which is an extension of an earlier one [see this 

 Review, Ser. A, iii, p. 163], gives in a series of tables the results of 

 further studies into the conditions of temperature and humidity as 

 they afiect the life-history of the fly. The complete life-cycle m.ay 

 occupy from 443 to 459 days in the case of average individuals passing 

 the egg, larval, and pupal stages during the warmest seasons, but is 

 more extended when these stages are passed during colder seasons. 

 One individual has been known to lay as many as 1,000 eggs, and as 

 there are 8 to 10 generations in a year, the fly multiplies very rapidly. 

 In Hawaii, where the climate is warm and equable and there is 

 abundant food supply, no agencies have been discovered that will 

 check the abundance of the fly. Neither parasites nor predaceous 

 enemies occur in the Islands, but it is hoped that future introductions 

 of melon-fly parasites may prove beneficial. No artificial means of 

 control have been successful, and these are not likely to be 

 satisfactory in Hawaii while the growing of the chief host-plants 

 remains in the hands of uneducated oriental labourers, who do not 

 practice clean cultural methods or co-operate in applying remedial 

 measures. 



A bibliography of 51 works is appended. 



Marsh (H. 0.). Life-History of Plutella maculipennis (Diamond-back 

 Moth).— Ji. Agric. Research, Washington, B.C., x, no. 1, 2nd July 

 1917, pp. 1-10, 2 plates. 

 Plvtella maculipennis, Curtis, is found infesting cabbage, cauli- 

 flower, rape and other cruciferous plants throughout the United States. 

 In Colorado there are 7 generations in a year. Adults emerge from 

 hibernation early in May and reproduction continues throughout the 

 smnmer. Eggs are laid on the under-side of leaves, cabbage being the 

 favourite host- plant, and the larvae burrow between the tissues of 

 the leaves. Tables of rearing records are given ; the life-cycle was 

 found to occupy from 16 to 47 days. While potentially a serious pest, 

 the diamond-back moth is normally held in repression by parasites, 

 the chief of which is the Ichneumonid, Angitia plutellae, Vier. This 

 parasite is occasionally infested by a Chalcidid hyperparasite, 

 Spilochalcis delira, Cresson. Other parasites of P. maculipennis are 

 Meteonis sp., Mesochorus sp. and a new species of Microplitis. When 

 the parasites are not sufficiently numerous to hold the larvae of 

 P. maculipennis in check, a spray consisting of 2 lb. Paris green and 

 6 lb. soap to 100 U.S. gals, water is an effective remedy. 



Moore (W.) & Graham (S. A.). A Neglected Factor in the Use of 

 Nicotine Sulphate as a Spray. -JZ. Agric. Research, Washington, 

 B.C., X, no. 1, 2nd July 1917, pp. 47-50. 



Cases of poisoning having been traced to greenhouse lettuce sprayed 

 with nicotine sulphate, experiments were undertaken to determine 

 ^C399) B 



