20 MISC. PUBLICATION 318, U. S. DEPT. OF AGRICULTURE 
Mexican bean beetle.—In certain parts of the country bean grow- 
ing is difficult because of a little black-spotted beetle, approximately 
ge ener one-fourth of an inch in length, that chews the 
op ae leaves of bean plants. Like the other beetles, or 
a a Coleoptera, it has two pairs of wings, the fore 
pair leathery and the hind pair clear. The 
adults are hemispherical in shape, and coppery 
brown in color with black spots; the larvae are 
bright yellow with many forked spines on their 
backs. The adults overwinter in protected places. 
Ficurs 45.— Mexican Most of the ladybeetles are beneficial, but this 
nein IEeule. one, the Mexican bean beetle ('pilachna varives- 
tis), is a pest. It can be controlled with derris or cube dusts or 
sprays. 
Colorado potato beetle—What boy or girl in most parts of the 
United States, when visiting a potato patch, has not, at some time or 
other, seen a yellow and black striped beetle and a small, soft-shelled, 
brick-colored grub with black spots along its sides, feeding on the 
potato leaves? This is the Colorado potato beetle. 
The adult is about three-eighths of an inch long. 
It has five black lines on each wing cover and 
black spots on the other part of the body. Of its 
four wings, the fore or outer are leathery, and 
the under wings are veinous and fold beneath the 
leathery wings when tha insect is not in flight. 
The potato beetle overwinters in the adult stage 
in the ground, and in the spring flies to potatoes 
or certain closely related plants and starts chew- : 
ing the leaves. Soon after the adults appear, Ficurn 46.— Colorado 
clusters of orange-colored eggs may be found on stale 
the under side of the leaves. The grubs which hatch from these eggs 
also feed on potato foliage, and, when growth is completed, burrow 
into the ground and go into the pupal stage, later to emerge as adults. 
There may be two generations a year in some sections. DDT, paris 
ereen, or lead arsenate is dusted or sprayed on the potatoes to control 
this beetle. The scientific name of this insect, which belongs to the 
order Coleoptera, is Leptinotarsa decemlineata. 
Spotted cucumber beetle.—Rather early in the spring 
in the most northern parts of this country there appears 
on beans, cucumbers, and various other plants, an elon- 
gated, greenish-yellow beetle about one-fourth of an 
inch in length. The head and legs are black. Because 
doe of 12 black spots on its back, 6 on each wing cover, and 
(8'96\\. because it chews holes in the leaves of very small cucum- 
‘\ ber plants, the adult of this insect is called the 12-spotted 
cucumber beetle. The larva feeds to a large extent on 
y ; corn roots, and in this stage it is known as the corn 
FicurE 47.—Spot- rootworm. This insect overwinters in the adult stage. 
ted cucumber The eggs are laid just beneath the surface of the soil in 
the early summer. Because the larvae feed on a great 
number of the roots of plants belonging to the grass family, and the 
adults on a wide variety of plants and flowers, the damage to any 
ee 7 
