49 



on pieces of paper in various parts of the field and kept under obser- 

 vation. Experiments in poisoning the ants with acetylene gas have 

 shown that this method of control is impracticable and gives uncertain 

 results. Vaporite sprinkled over the seed-bed exercised a deterrent 

 action for a short time, but the effect soon disappeared. Attempts 

 to attract the ants to various baits met with success and pieces of ripe 

 avocado pear and meat attracted them in large numbers. These 

 ants are more likely to be abundant in newly cleared land or in land 

 in which maize, cotton or sugar-cane has been grown. 



de Charmoy (D. d'E.). Insects injurious to stored Grain in Mauritius. 



— Dept. Agric, Mauritius, Port Louis, Bull. no. 2, June 1915, 

 p. 16, 8 figs. 1 plate. [Received 16th December 1915.] 



The most important insect pests of maize in Mauritius are Calandra 

 oryzae (rice weevil), Dinoderus minutus (maize beetle or bamboo borer) 

 and the maize Tineid. The life-cycle of G. oryzae in Mauritius lasts 

 30 or 40 days ; it is shorter in summer than in winter and varies with 

 the locality. The number of generations produced annually varies 

 from six to eight on the sea-coast, while in more elevated districts it 

 is probably less. Maize is most severely attacked by this insect when 

 it has been shelled and dried. If kept in cobs, in well lighted and 

 ventilated stores, it remains a longer time without becoming infested. 

 D. minutus is a cosmopolitan species, having been recorded in 

 Ouadeloupe, Java, India, Brazil and Tahiti. Reproduction occurs 

 throughout the year, the maximum number of generations produced 

 being about seven. Besides treatment with carbon bisulphide, it is 

 advisable, in places where maize is stored, to destroy all dry bamboos 

 used as fences or otherwise. The cob is frequently attacked by the 

 maize Tineid before harvest. The life-cycle is passed within the 

 central core of the cob. Maize kept in cob and heaped in dark and 

 damp spots is thus much more liable to attack than shelled maize kept 

 in well- lighted stores. 



Rice is attacked by C. oryzae and by Ephestia cahiritelh: As a 

 remedy for the former species, sulphur dioxide appears to be the most 

 practical and economical compound to use as a fumigant. E. cahiritelh, 

 occurs also in India, in rice and flour, and in Egypt and America, 

 where dried fruits, almonds, nuts and cacao-beans are attacked. 



Seeds of leguminous plants, e.g. Cicer arietum (gram), Phaseolus 

 vulgaris (French bean), peas, Vigna catjang (cowpea), and Cajanus 

 indicus (pigeon pea) are attacked by the beetles, Bruchus obtectus, 

 B. chinensis and B. quadrimaculatus. The initial infection of the seeds 

 takes place in the field, when the eggs are deposited on the pods. 

 Hatching takes place in from four to six days. The larva at once 

 enters the pod and feeds on the seeds. The duration of the larval 

 stage is from two to three weeks. The nymphal stage lasts five or six 

 days in summer. Bran, flour and other foodstuffs are injured by 

 Sylvanus signatus and S. surinamensis (saw-toothed grain beetles) and 

 Tribolium ferrugineum (flour beetle). A brief account of remedial 

 measures against these insects is given. 



