138 The Sweet Potato 



black flea-beetles. The leaves are affected by having 

 channels eaten out hi both surfaces, the work being 

 characteristic of this particular species and quite dif- 

 ferent from other flea-beetle injury. As a result of 

 these attacks, many of the leaves of the newly set plants 

 are killed outright; some turn brown and partially de- 

 cay. New leaves usually put out from the stalk and 

 thus prevent the plant from dying, but this injury 

 checks the growth of the plants to a considerable extent, 

 and in some cases kills them. Some seasons this injury 

 is more serious than others, and some authorities claim 

 that it is worse on low land. It is most serious on lands 

 that were planted the previous year to potatoes, and the 

 first injury is usually near hedge-rows, old fences, or 

 other rubbish, where the beetles have hibernated during 

 the winter. This beetle is about Ko inch long, thick- 

 set, of a brownish color, and the wing-covers when seen 

 under the microscope are distinctly furrowed. 



The beetles hibernate over winter in rubbish under 

 logs, leaves, or other vegetation, and emerge in the 

 spring, usually about May. They mate as soon as they 

 have fed, and after doing damage to the young plants 

 that are set in the fields they usually disappear about the 

 middle of June. Very little is known about the early 

 stages of the insect, and they have never been found 

 on sweet potato plants. The larva most probably feeds 

 on the refuse of bindweed and morning-glories ; it is a 

 slender white grub about Ys inch long. The beetles 

 appear in August, but do not as a rule feed on the 

 tough sweet potato plants at this season. 



Many of the beetles will be killed, if, when the plants 

 are taken from the draw-bed, they are dipped in a solu- 

 tion of arsenate of lead 1 pound to 10 gallons of water. 



