172 The Potato 



The adult beetle is oval in shape, about three-eighths of 

 an inch in length and a trifle narrower than long. The 

 ground is yellow and the wings are marked by ten black 

 lines running lengthwise. There are also black markings 

 on the thorax (see Fig. 10). These insects have great 

 power of endurance. They will walk for great distances in 

 search of food, and it is said by direct experiment they are 

 known to have lived thirty days without food. Their 

 eggs are a bright yellow when fresh and the young are 

 dark red or brown grubs with black heads and markings 

 of black spots in double rows 

 on each side. The color be- 

 comes lighter as the grubs 

 mature. 



Control. — The Colorado 

 potato-beetle is controlled by 

 the use of poisonous sub- 

 * ^ stances which either in solu- 



FiG. 10. Potato bug, larva and ,• • i 



mature beetle enlarged. tion or suspension are sprayed 



upon the vines. The most 

 common of these arsenical poisons are paris green, arsenate 

 of lead or arsenate of soda. Any one of them may be 

 sprayed upon the vines alone or mixed with bordeaux mix- 

 ture and applied. Poison is usually necessary only for the 

 first two regular sprayings, but should be added at any time 

 the larvae become numerous. The eggs should be watched 

 carefully, and after they are well hatched and the young 

 have begun to feed, the first application of the poison 

 should be made. A second spraying will doubtless be 

 necessary in ten days to two weeks. The necessity for 

 subsequent applications of poison will be determined by 

 any later appearance of the pests. The first sprayings 

 should not be delayed too long, as the larvae develop very 



