Insects Affecting Sweet Potatoes 143 



full grown the larvae average about % inch. They are 

 slightly convex, of a pale yellowish color, marked with 

 numerous dark brOwn tubercles and prominent lateral 

 spines. The pupa is of a yellowish color, marked with 

 dark brown which in titne becomes almost black. 



Control of tortoise beetles. 



From the similarity of life history and habits of 

 these closely related species, their control may be the 

 same. The adult beetles do the bulk, of the' injury just 

 after the plants are set. It is advised that they be dip- 

 ped in arsenate of lead before setting, as for the flea- 

 beetle. If the beetles become serious in the field, plants 

 should be sprayed with arsenate of lead, 4 pounds to 

 50 gallons of water. All places of hibernation, such as 

 fence-rows, hedge-rows, woodlands and trash, should be 

 destroyed during the winter, as this will kill many of 

 the adults in hibernation. 



SAW-FLIES. (Fig 15) 



Probably the first injury from saw-flies was reported 

 from Ocean Springs, Mississippi, in 1886, by C. V. 

 Eiley,^ the larvae practically ruining an entire crop of 

 sweet potatoes. This pest is very injurious in certain 

 seasons, the most damage- probably being in the southern 

 states. Saw-flies have since been found on sweet pota- 

 toes and morning-glories in Nebraska, Iowa, Illinois, 

 and several other central and eastern states. The in- 

 jury from these flies cannot be said to be serious, and 

 the outbreaks are more or less sporadic and local. The 

 writer, in 1919, found about a 50 per cent defoliage 



1 C. V. Riley, formerly of Bureau of Entomology, 



