436 



Phillips (W. J.), Underhill (G. W.) & Poos (F. W.). The larger- 

 Corn Stalk-borer in Virginia. — Virginia Agric. ' Expt. Sta., 

 Blacksburg, Tech. Bull. 22, June 1921, 30 pp., 3 figs., 7 tables, 

 4 plates. [Received 23rd June 1922.] 



The history, distribution, food-plants, and natural enemies of 

 Diatraea zeacolella, Dyar (larger corn stalk-borer) in Virginia are 

 recorded, and a brief description of all stages of this insect with its 

 life-history and the character and extent of the injury it causes are 

 also given. There are two generations a year, hibernation being passed 

 in the larval stage. Eggs are laid in clusters of from 3-15 and hatch 

 in 10-15 days. The larvae first feed on the unfolded leaves of the 

 heart of the plant and then work down into the stalk. The larvae of the 

 second generation feed in the heart of late maize and also tunnel 

 the stalks severely. 



Late maize suffers less than early as it is not so severely attacked by 

 the first generation, but for conditions in Virginia late planting is. 

 not recommended, as equal loss is caused to this crop by other insects. 



An economical and simple remedial measure is ploughing the stubble 

 out with a turning plough, then harrowing the land not later than 

 10th December and allowing it to remain exposed till the first week 

 in March. Data from the experiments undertaken in 1920-21 in an 

 average winter showed almost 100 per cent, control by this means. 

 They also proved that unusually mild winters greatl}' favour 

 hibernating larvae in both ploughed and unploughed stubble. 



List (G. M.). The Mexican Bean-beetle.— Co/ora^o Agric. Expt. Sta.,. 

 Fort Collins, Bull. 271, August 1921, 58 pp., 11 figs., 19 tables. 

 [Received 23rd June 1922.] 



Epilachna corritpta, Muls. (Mexican or spotted bean-beetle) is a very 

 serious pest of the bean crop in the infested sections of Colorado. 

 Its attacks are confined almost entirely to the true beans. Hibernation 

 is passed in the adult stage, the insects emerging during the middle and 

 latter part of June. In Fort Collins there is one complete generation, 

 and in some seasons about 25 per cent, of the first-brood adults deposit 

 second-brood eggs, and second-brood larvae are often quite abundant. 

 A few individuals pass through a second complete life-cycle, emerging 

 as adults late in the autumn. The numbers of the second generation 

 are small compared with the first, the percentage being greater in 

 the warmer sections of the State. Their mortality is high, and the 

 larvae do little damage. The maximum period of injury usually 

 occurs during the end of July and in August. 



Under certain conditions hand-picking of the hibernated adults, 

 and first-brood eggs may be practised. The most satisfactory remedial 

 measure is spraying with zinc arsenite or lead arsenate at the rate 

 of 1 lb. of powder to 40 U.S. gals, water, using 50 U.S. gals, water in 

 the case of zinc arsenite. The spray should be applied to the lower 

 surface of the leaves, and as many as three applications may be 

 necessary. Beans are very susceptible to injury from arsenical 

 sprays, zinc arsenite causing the least amount of injury, though 

 that from lead arsenate has not been serious enough to make its 

 use impracticable. Only beans of the dwarf or bunch type should be 

 grown. Early planted beans of an early maturing variety are most 

 easily protected, and are usually most successful in badly infested 

 sections. 



