June 1896.] 



INJURIOUS INSECTS AND FUNGI, 



35 



fly long distances. Pairing takes place in June, and the female 

 places her spindle-shaped yellowish eggs on the soft green pods 

 of the bean plants. From the eggs, yellowish-white maggots 

 with black heads emerge in from 13 to 15 days, and, making 

 their way into the nearest beans, burrow into them. They 

 remain in the beans, living on their substance, until they change 

 to pupse, and finally to beetles. In some cases, the beetles leave 

 the bean during the winter, but generally they stay there until 

 the early spring. They may be found as late as May in the 

 beans. The maggot is fleshy, with strong jaws and rudimentary 

 legs, and is rather more than one-eighth of an inch long. It 

 feeds on the contents of the bean for a period varying from 

 three to four weeks, when pupation occurs. If infested beans 

 are examined, small black punctures quite closed up may be 

 noticed upon them, evidently made by the maggot in entering 

 them while they were young and soft. There are also other 

 holes from which the beetles have escaped, or are escaping, as 

 shown in the illustration, and small, almost transparent, circles 

 of skin still covering holes contain ing beetles. These circular 

 covering doors are left by the maggots in such a way that the 

 beetle can escape by using gentle pressure. Upon splitting open 

 a badly infested bean lengthways, it is seen that the greater part 

 of the inside has been consumed, and that some of the holes run 

 into each other. At the end of each hole there is a collection of 

 yellow debris of bean flour and excrementitious matter. The 

 beetles also eat the contents of the bean, as bean flour has been 

 found in their intestines. 



Professor Riley, in 1882, discovered that the American Bean- 

 beetle, Bruchus fabce, Fitch, Bruchus obtectus, Say, much 

 resembling Bruchus rufimanus in form and habits, bred in 

 warehouses and granaries upon dry beans, as well as in the fields 

 upon the growing bean pods — that it had, in fact, two genera- 

 tions. The egg was laid upon the dry bean. After 16 days 

 the maggot appeared, penetrated the bean, and lived in it, feeding 

 on its flour. Professor Lintner confirms this statement. 



Remedies and, Methods of Prevention. 



No remedial measures are available against the attacks of 

 this insect. Great care must be observed in purchasing seed 

 beans and in noting whether they are infested. If infested 

 beans are sown there is not only possible failure of germination, 

 or weakness of plants corresponding to the amount of infestation, 

 but there is the risk of introducing the beetle wherever the seeds 

 are sown. Infestation is indicated by very minute black punc- 

 tures, by open holes, or by small circles of almost transparent 

 skin on the beans. Foreign seed should be especially examined, 

 as it is far more extensively infested than that produced in 

 Great Britain. Beans imported from America would probably 

 contain another species of beetle, Bruchus fabce, Fitch, Bruclms 



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