THE BEAST LADYBIRD. 17 
left these plants at once. Larva? hatching from eggs deposited before 
the application of the poison were also killed where they fed on 
sprayed leaves. The older larva?, however, appeared to die of star- 
vation rather than from eating the poisoned foliage. 1 
ARSENITE OF ZINC. 
Experiments were made with powdered arsenite of zinc at the 
rate of 1 pound to 20, 30, 40, and 60 gallons of water, respectively. 
The burning effect on the foliage was in all cases less than where 
arsenate of lead or Paris green was applied, and usually a larger 
proportion of the insects was killed. The burning was most ap- 
parent about the margins of the holes made in the leaves by the in- 
sects in feeding. Many larva? died after eating the poisoned foli- 
age, but, as with the other arsenicals, the effect on the beetles was 
uncertain. All factors considered, the most promising results were 
obtained with zinc arsenite at a strength of 1 to 40. This caused 
comparatively slight burning and killed an appreciable number of 
the insects. It should not be overlooked, however, that the killing 
of the beetles is uncertain and that the burning effect on the plants 
will vary greatly with their age and tenderness. It is probable that 
Mexican beans, with relatively tougher foliage, would show less 
injury from burning than the more tender-leaved string beans 
treated in these experiments. Zinc arsenite in experiments con- 
ducted in New Mexico by Merrill at the rate of 2 pounds to 50 
gallons of water produced practically the same results as powdered 
lead arsenate. 
PARIS GREEN. 
Experiments were made with Paris green at the rate of 1 pound 
to 60 and to 80 gallons of water. As a result of these tests the 
beans were destroyed by burning due to the presence of free arsenic. 
Most of the larva? were killed, but many of the beetles escaped. In 
the face of these results, Paris green at these strengths can not be 
recommended as a means of controlling the bean ladybird. Every- 
one who has tried Paris green has experienced the same failure. 
Sodium arsenite is at least equally dangerous. 
SUMMARY OF SPRAYING EXPERIMENTS. 
The experience of entomologists in spraying with arsenicals in 
Colorado and New Mexico tends to show that arsenate of lead acts 
largely as a repellent rather than as an insecticide, which is true 
also of its effectiveness in the case of such other pests as the striped 
cucumber beetle. 
Bordeaux mixture, which has come to be considered a standard re- 
pellent against flea-beetles, should be tested against the bean lady- 
bird in the future. 
1 Powdered lead arsenate at the rate of 5 pounds to 50 gallons of water was no more 
effective but did no damage to the plants in experiments made. It should not be used at 
this strength. 
