INSECTS INJURIOUS TO POTATO, ETC. 21/ 



cycle from egg to adult may be passed in a single month, 

 and the last generation of beetles issues early in autumn and 

 re-enters the earth for hibernation. Fluctuation in numbers 

 of the Colorado beetle is noticeable at least locally every sea- 

 son, and is largely attributable to the activity of its insect ene- 

 mies and to atmospheric conditions. Up- 

 wards of 30 species of insects prey upon 

 this beetle. One of the most important of 

 these is a predaceous ground-beetle, Lcbia 

 grandis Hentz (fig. 137). 



Remedies. — No other methods are nec- 

 essary than the free use of Paris green 

 or arsenate of lead and mechanical means 

 for its destruction. 



Hand-picking, if employed early in the 

 season, is of great value, but where large F'g- i37. — Lfiw ^mncis. 



, , , , , Enemy of the potato 



areas are planted other methods are nee- beetle, ma^xxdel) 

 essary. Gathering the beetles and their 



larvae in pans containing a little water on which a little kerosene 

 is floating, is an effective remedy. Methods of preparing and 

 applying the arsenicals are given in the chapter on insecticides. 



If the grower can secure the cooperation of his neighbors in 

 the destruction of this pest, and will also kill the insects on 

 wild plants, much can be done toward limiting its numbers in 

 small areas. It seldom, if ever, migrates as formerly, and there 

 is not so much likelihood of reinfestation from a distance. It 

 is always wisdom to keep down weeds, and in the treatment of 

 the present insect, if they were cut before seeding, it would 

 serve a dual purpose in preventing the increase of weed as well 

 as insect. The susceptibility of the "slugs" to extreme heat, 

 indicates that the remedy for the asparagus beetle of brushing 

 them from the plants on hot dry days will be effective. 



The Potato Flea-beetle (Epitrix cucumeris Harr.). — Much 

 injury to potato is inflicted by flea-beetles which attack most 



