214 



AJV ECONOMIC ENTOMOLOGY. 



follows shortly thereafter, resulting in a fall supply of beetles, 

 which, as a rule, hibernate. Sometimes a third partial brood of 

 larvae reaches the pupal state, and hibernates in that condition. 

 The arsenites are well-known and approved remedies, used at the 

 rate of one pound in from seventy-five to one hundred gallons 

 of water, and several machines especially intended for spraying 

 potato-fields are on the market. The insect maintains itself 

 unchecked, because, while active war is waged against the first 



Fig. 206. 



The Colorado potato-beetle, Doryphora lo-lineata. — a, a, egg patches ; b, b, b, larvae in 

 different stages of growth ; c, pupa; rf, beetle; e, its elytra enlarged. 



brood, little attention is paid to the second, and this is usually 

 allowed to mature and provide for a new crop the year following. 

 Spraying should be done first as soon as the beetles begin feed- 

 ing, to prevent oviposition if possible ; it should be done a sec- 

 ond time when larvae appear generally, and it should be done as 

 often thereafter as beetles or larvae are noticed infesting the 

 plants. 



The species of Diabrotica are rather slender, with long an- 

 tennae ; of a green or yellow color, with black spots or stripes. 

 The adults feed on leaves, flowers, or pollen, but the larvae, which 

 are white and slender, usually feed in the roots or stems of plants. 

 One of our most common forms, D. vittata, is known as ' ' the 

 striped cucumber-beetle," and is yellow with black stripes on the 



