258 



is sufficient to kill all the larvae after an exposure of one day. Other 

 means of destroying this pest with carbon bisulphide or exposure to 

 dry heat have already been noticed [see this Review, Ser. A, vi, pp. 

 329, 465]. Late planting with a view to preventing infestation has 

 not been found successful, the greater freedom from weevils being 

 counteracted by the fact that the crop gets rapidly poorer as the 

 summer advances, as well as being severely damaged by the caterpillars 

 of small Lycaenid butterflies. 



B. ntfimanus, Boh., has hitherto been recorded in South Africa only 

 from the Cape Peninsula, breeding in broad beans, tick beans and horse 

 beans. The adults appear in September and may be found up to the 

 middle of December. The eggs are deposited on the green pods and take 

 from 16 to 24 days to hatch. The larva takes 5 or 6 months to develop, 

 and more than one can reach maturity in a single seed. The adults 

 begin to emerge towards the end of February and continue to do so 

 at intervals until September ; the majority appear on warm days 

 in autumn and winter, this species being more intolerant of cold 

 than B. pisorum. Measures recommended for B. pisorum apply equally 

 well to B. rufimanus, but in using the hot-water remedy beans must 

 be immersed for 10 minutes owing to the thickness of their integument. 



B. obtectus, Say, has a wide distribution in South Africa, infestation 

 being heaviest in the Eastern Province. The adults appear during 

 January and are found throughout the rest of the summer. The 

 eggs are not deposited, as has been stated, inside the green pods, but 

 inside the dry, ripe pods. The eggs hatch in from 10-13 days in the 

 height of summer, and in from 20-24 during winter. More than one 

 larva can reach maturity in a single bean, the process occupying 

 3-4 weeks during summer, and 6-8 weeks in winter. The pupal stage 

 lasts some 8-11 days in summer and some 18-25 days in winter. The 

 adults remain in their cells only a few days in summer, but the dormant 

 period in the winter depends largely on the weather. Varieties of 

 beans immune to attack by this species are :■ — Phaseolus hinatvs 

 (Lima bean), Vicia faba (broad bean), Muciina pruriens var. idihs 

 (velvet bean) and Glycine hispida (soya bean), while P. vulgaris (French 

 or kidney bean) and P. ynultiflonis (runner bean) are only injured to 

 a slight extent. B. obtectus has some 4 generations a year, 

 that in winter occupying about 4 months, that in summer 2 

 months, while in spring and autumn a generation takes about 3 months. 

 Since breeding takes place in dry, stored beans, the necessity for 

 treating them as soon as possible after harvesting is obvious. The 

 remedies advised against B. pisorum are equally efficacious against 

 B. obtecins, and an additional measure, useful in some cases, consists 

 in mixing the beans with an equal volume of dry, finely pulveri&ed 

 soil, ground limestone rock, or air-slaked lime. Beans kept for seed 

 may be protected by soaking them in paraffin for an hour and then 

 spreading them in the sun to dry, 93 per cent, of such seeds germmatirig 

 after a lapse of 10 months. 



B. chinensis, Thunb., is widely spread in South Africa, and is quite 

 common at the Cape, where it appears among cowpeas during February. 

 The eggs are deposited on the outside of the dry. ripe pods and hatch 

 in from 10-21 days, the larval stage lasting some 4 or 5 months during 

 the cold season, but only about 5 weeks in summer. The adults do 

 not lie dormant in their cells for any length of time, but at the Cape 



