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 

 one- fourth of an inch in length, that chews the 

 leaves of bean plants. Like the other beetles, or 

 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. 

 figuee 45. — Mexican Most of the ladybeetles are beneficial, but this 

 bean beetle. one ^ fj^Q Mexican bean beetle (Epilachna 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 the 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, 

 clusters of orange-colored eggs may be found on 

 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. Paris green 

 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 decernlineata. 



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 

 of 12 black spots on its back, 6 on each wing cover, and 

 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 

 corn roots, and in this stage it is known as the corn 

 FiGtmE 47.-spot- rootworm. This insect overwinters in the adult stage. 

 bettie 110 umber ^ ne e £g s are I a id 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 



Figure 46. — Colorado 

 potato beetle. 



