299 



A resolution was passed by the meeting demanding appropriate 

 legislation and urging all those in authority to use every effort to 

 prevent the entrance of this pest into Texas. 



Merkill (D. E.). The Bean Beetle (Epilachna conupta, Muls.). — New 

 Mexico Agric. Expt. Sta., State College, Las Criices, Bull. no. 106, 

 April 1917, 30 pp., 6 figs. [Received 15th May 1918.] 



Epilachna conupta, Muls. (bean beetle) is the most serious bean 

 pest in New Mexico, destroying on an average about 10 per cent, 

 of the crop. The adults hibernate and do not appear on the bean 

 plants until after the first week in June. About a week later they 

 begin ovipositing on the under-sides of leaves, and after an incubation 

 period of 4-9 days the larvae appear and immediately begin to feed, 

 eating off the lower epidermis and the green substance of the central 

 layers of the leaf, until only the upper epidermis and veins remain 

 as a whitish skeleton. Much more damage is done in this way than 

 by the adults, which simply eat holes here and there entirely through 

 the leaves. There are two overlapping broods in a year, first-brood 

 larvae appearing from 19th June to 23rd August and second-brood 

 larvae from 20th July to the end of the season. The maximum damage 

 is therefore done between 20th July and 23rd August when the two 

 larval broods occur simultaneously. The pupal period lasts about 

 4 days. Adults that survive until the food-supply is gone scatter 

 when the cold weather begins and seek shelter under old \nnes, weeds 

 or rubbish that may be in or near to the bean fields, and sometimes 

 partly bury themselves in the soft soil beneath. 



As beans are the only food-plants, control should be comparatively 

 easy. Clearing the fields of all old plants and rubbish, and ploughing 

 in autumn and winter, will obviously destroy many hibernating adults. 

 Rotation of crops and removing the new fields as far as possible from 

 the old ones will prevent many adults from reaching their food-plants 

 in the spring. Early planting in spring will allow the crop to set 

 and mature before the beetles appear. Very late planting, if prac- 

 tised universally in a community, would cause many beetles to die 

 before finding plants on which to oviposit. A table gives dates for 

 planting in relation to attacks by E. corrupta, and shows that the date 

 of planting may be anticipated by one or two weeks at least. Although 

 trap-crops have not been tested experimentally, it is expected that 

 excellent results would be obtained by using a late trap-crop, consist- 

 ing of a small patch of beans, to attract adult beetles in late summer 

 after the main crop is gathered. Hand-picking is useful on small 

 areas only. 



Natural enemies of E. corrupta are few, the beetles being protected 

 from attack by a repellent fluid secreted at the leg joints. The Cocci- 

 nellid, Hippodamia convergens, and an ant have been observed eating 

 the eggs, but among all the insects handled during the life-history 

 investigations no parasites were observed. 



Sprays tested for control of E. corrupta on bean plants included 

 lead arsenate in dust and liquid form, zinc arsenite, sodium arsenite, 

 Blackleaf 40, and combined arsenate of lead and lime-sulphur. These 

 gave varying results ; powdered lead arsenate (2 lb. to 50 U.S. gals, 

 water) killed young larvae feeding on the sprayed leaves, but the 

 adults were repelled and would die of starvation rather than eat the 



