THE BEAX LADYBIRD. 



19 



chiefly on the upper surface, cutting irregular holes in and through 

 the leaves, while the larvse feed on the lower surface and skeletonize 

 the leaves, seldom cutting through them. 



The adult is a robust beetle, about one-fourth inch in length, of 

 oval outline, pale brown, with each wing-cover marked with eight 

 small black spots. The larva is light yellow and armed with 

 branched spines. 



The yellow eggs are deposited from about the middle of June 

 until August on the lower surface of the leaves, in clusters of 40 

 or more, and sometimes to the number of 1,500 by a single female. 

 The larvae feed at first in colonies, but with larger growth scatter 

 and become more or less solitary. The life cycle may be passed in 

 summer in from 22 to 

 30 days; the eggs 

 hatch in from 4 to 9 

 days ; the larval period 

 is between 15 and 21 

 days; and the pupal 

 period varies from 3 

 to G days. In colder 

 weather, however, 

 these periods are 

 longer. Two genera- 

 tions or " broods " are 

 produced annually. 



Cold weather in late 

 autumn has the effect 

 of destroying the in- 

 sects, and their eggs 

 are also destroyed by 

 three species of pre- 

 dacious ladybirds. 



In the control of the bean ladybird preventive measures are the 

 most efficient, consisting of hand picking and brushing from the 

 plants, clean culture, and early and late planting. Arsenicals possess 

 some killing properties, but in the main act as repellents. Spraying 

 with arsenate of lead. 1 or 2 pounds (powder), and with arsenite of 

 zinc, 1 to 1| pounds (dry) , to 50 gallons of water, are the most prom- 

 ising. Bordeaux mixture, 4-4-50 formula, should be used alone and 

 in combination with these arsenicals. Additional tests must be made 

 with these substances to ascertain the most effective and economical 

 combination that may be applied to the bean plants without scorching 

 or burning the leaves. 



For the treatment of large areas infested by the bean ladybird, a 

 traction sprayer with nozzles arranged for side spraying of the type 

 shown in figure 5 is useful. Owing to the danger of scorching bean 

 foliage, it is desirable that an up-to-date sprayer should always be used. 



Fig. 5. — Traction sprayer with nozzle arrangement for 

 side spraying, of type useful for spraying beans for 

 the bean ladybird. 



