February, '22] cotton states entomologists proceedings 107 



The Mexican Bean Beetle {Night Session) 



At this session Dr. Hinds gave an illustrated talk with a most unusual set of slides 



showing the Mexican bean beetle in all of its stages and Mr. Graf discussed the spread 



of the pest work with insecticides, and the result of effort to find natural enemies. 



Many of the illustrations appear in Dr. Hinds' bulletin on the Mexican Bean Beetle 



and in the same bulletin is a thorough discussion of the life-history and habits of this 



pest In Alabama there were four generations of the insect m 1920. In 192 1 , although 



there was ample time for the development of a 5th generation, it did not appear. 



In 1921 Dr. Wickham left Alabama when the infestation was at its crest and when he 



arrived at the high elevations in Mexico to collect parasites he found that this pest 



had practically disappeared for the season. In New Mexico the insect has but two 



generations a year. It is thought that the cool nights might possibly cause a chemical 



change in the leaves which may cause breeding to stop. ., i ^^ 



The discussions of Dr. Hinds and Mr. Graf showed that the pest was evidently not 



at all settled to eastern conditions. In 1920 it migrated at the end of the season 



whereas in 1921 most of its migrating was done in early summer. 



Dr Hinds pointed out that an important fact in considering the possibihty ot 

 spreading this pest in shipments of nursery stock is the fact that a female fertilized 

 in the fall may winter successfully and deposit fertile eggs the following spring. N ew 

 infestations may thus be established by transporting a single hibernating female to 

 a new locality. ^ . ,, , • i • + „i: 



It now seems certain that the insect was introduced into Alabama m shipments ot 

 alfalfa hay from Utah. Dr. Ball states that before the war the bean growing area 

 in Utah was isolated from the alfalfa growing regions but during the war it became 

 profitable to grow beans in the alfalfa regions and for the first time the_ beetle had an 

 opportunity to be carried out of the state in alfalfa hay. It was at this time that it 

 was carried to Alabama. . 



In regard to host plants, mung beans and velvet beans seem to be rather resistant 

 to this insect. Beggar weed seems to be a favorite host. Cowpeas seem not to 

 be attacked ordinarily until they are 20—30 inches high, according to Mr Grat. 

 Dr. Hinds has reared the insect through all its stages on alfalfa and velvet _ beans. 

 It will feed on non-leguminous plants when it is starved to it. The insect is primarily 

 a leaf feeder though it will feed on the pods when the leaves are gone. In order ot 

 their susceptibility to the Mexican bean beetle Dr. Hinds places the legumes as 

 follows: (1) kidney beans, snap beans and corn-field beans, (2) lima beans, {6) 

 cowpeas and (4) soy beans. i • 4. i,^ 



The destructiveness of the pest is well known to all southern entomologists wno 

 have followed the history of the pest. Dr. Hinds states that m 1919 a farmer near 

 Birmingham made $400 on an acre of late beans. The following year he planted two 

 acres the first week of August, had to plow them under the first week of September, 

 and did not get enough beans to can for home use. This case is quite typical, i He 

 insect will cause a 75% loss to the bean and pea crop of the territory mfested. 



According to Mr. Graf control of the insect bv the use of arsemcals is very ditncult. 

 The stable arsenates are not effective. They seem to pass through the digestive 

 tract of the insect before thev can be acted upon. On the other hand the insec- 

 ticides which are effective against the insect are very injurious to the tender foliage 

 of legumes. In hot dry weather effective insecticides can be used without mjury but 

 if the weather is humid, injury will result. The most stable forms of calcium and lead 

 arsenate will strip the vines. If this pest is to be controlled by the use of insecticides, 

 a new one will have to be used. , 



Control by the use of natural parasites is equally unpromising. After seven weeKs 

 in Mexico, Prof. Wickham found only one parasite, a Tachinid parasite which attacks 

 the adult beetle. This was found quite by accident. . • r- • qa 



The present range of the insect in the South includes 36 counties in_ Georgia, _.i4 

 counties in Alabama, 34 counties in Tennessee, and 2 counties each m Kentucky, 

 North Carolina and South Carolina. 



Sweet Potato Weevil Eradication (Morning Session, December i) 

 This subject was discussed by Mr. J. E. Graf. It was pointed out that the sluggish- 

 ness of this insect made it an easy subject for eradication. The matter of eradication 

 is not a technical one but is rather a problem of thorough extension work with a view 

 to getting farmers of the infested area to co-operate. Where one can control the 

 planting seed and slips which are used in the infested area and can combine this with 

 clean culture, the problem of eradication has been solved. 



