MINNESOTA BILL BUGS. 159 



From a study of the life-cvcle, it will l)e seen that the best time 

 to plant corn is at least ten days (15 is better) after the adults 

 make their appearance in the spring. The greatest amount of dam- 

 age is done before the mating season. 



Another significant fact is that there are years of abundance 

 and years of comparatively few billbugs, the former following a 

 year of high water. Just wdiat part parasites play in this role is still 

 a question. 



Two other methods of control suggest themselves ; crop rota- 

 tion and the use of poisons. Where practicable, drainage W'Ould 

 no doul)t be of consideralde help, provided the extra expense would 

 l)e compensated for. 



Crop Rotation. 



Rotating corn with potatoes, timothy, or wheat, to be again 

 followed by corn, does not rid the field of billl)Ugs. If rotation is 

 followed, fall plowing, followed by the disk-harrow^ or harrow, is 

 advised : again harrow or disk in the spring, if a new field of Cy- 

 pcnis cscidcntiis was broken in the fall. Sow the field to a root 

 crop, such as beets, or seed to onions or cabbage. This will demand 

 very thorough cultivation, thus keeping down volunteer nutgrass. 

 Manure in late summer or early fall and seed to clover, or manure 

 and fall-plow% seeding to corn the following spring, this to be fol- 

 lowed by a legume. 



Other combinations may be worked out according to controlling 

 local conditions as : 



First Year — Onions, beets or cabbage. Farly cabbage may l^e 

 followed by certain varieties of beans or peas. Field to be manured 

 and plowed in the fall. 



Second Year — Corn, timothy, wdieat, or potatoes. 



Third Year — Seed to clover or some other leguminous crop. 



While the above may not be an ideal crop rotation for bottom 

 land, yet the yellow nutgrass must be completely killed out or the 

 land summer fallowed. 



Poisoning. 



Since the adults are very greedy when they first make their 

 appearance in the spring and are known to be very fond of ear 

 corn, it is quite probable and even possible that broken bits of ear 

 corn could be soaked in water containing sweetened arsenicals and 

 then scattered about over the field. The objection to this method 

 would be the possible killing of birds; how^ever, the evidence of 

 birds being killed by arsenical spray methods is negative. 



