249 



is certainly erroneous for the Transvaal. The adults are nocturnal 

 and are attracted to lights, but do not fly far. Under natural con- 

 ditions the adult life is short. Ten generations of the insect were reared 

 in a few days over a year in insectary cages at the same temperature 

 as in the open. Infested cabbages are constantly sent by rail, and 

 thus the insect is disseminated. 



The principal predaceous enemy is a large green Mantid, Spliodro- 

 mantis gastrica, which destrpys many of the larvae. Unfortunately 

 this does not appear until October, when much damage has already 

 been done. An Ichneumonid parasite was reared from the pupae, 

 but occurs in insignificant numbers. Another Hymenopterous para- 

 site was observed to be very abundant in Cape Colony a few years ago. 



Control in the larval stage is comparatively easy with an arsenical 

 spray, to which 2 lb. resin should be added to every 50 U.S. gals, of 

 spray in order to render the insecticide adhesive. Cabbage and 

 cauliflower plants grown in seed beds that have become infested should 

 be sprayed before they are planted in gardens or fields. For infestation 

 after the heads have formed tobacco extract or tar water should be 

 used. All old plants should be destroyed. 



HuTSON (J. C). Report of a Visit to St. Vincent during November and 

 December 1917. A Preliminary Report on Certain Plant Bugs 

 connected with Cotton in St. Vincent. — Colonial Office MS. 

 [Received 2nd May 1918.] 



This report, as indicated by its title, records preliminary observa- 

 tions on certain pests injurious to cotton in St. Vincent and the neigh- 

 bouring islands of Bequia and Batawia. The results of the life- 

 history experiments will be published separately at a later date. 



Dysdercus delauneyi (cotton stainer) has been until recently by far 

 the most serious insect pest of cotton in the West Indies. It lives 

 during the period between the cotton seasons by breeding on the pods 

 of the silk cotton tree {Eriodendron anfractuosum) and the John Bull 

 tree {Thespesia populnea), and by the eradication of these wild food- 

 plants the insect has been reduced to a negligible quantity as a pest 

 of cotton in St. Vincent. A similar campaign is now being carried 

 on in Bequia, where it is realised that the cotton crop will never 

 be a good one until D. delauneyi is kept under control. In Batawia 

 it has been found necessary to eradicate the wild okra {Malachra 

 capitata) also. Suggestions for the control of D. delauneyi throughout 

 the islands include a close season for cotton during April. By this 

 means the insect would be deprived of cotton plants from March to 

 July, since cotton j^lanted in May does not flower before July. In 

 conjunction with the eradication of wild food-plants the cotton stainer 

 would thus be deprived of its main sources of food supply during a 

 critical portion of the year. Traps of cotton seed, seed cotton or 

 cotton seed meal should be used just before the cotton begins to flower, 

 the insects attracted by these traps being killed with gasolene torches. 

 Individuals of D. delauneyi should be collected in the field, the small 

 numbers now occurring having made this measure practicable. All 

 cotton seed and refuse should be cleared at frequent intervals from 

 the neighbourhood of cotton houses or ginneries. The plants should 

 be picked clean of all open bolls. 



