92 



Cr'NTROIv. 



No farm crop is immune from wireworm attack although many farm.- 

 ers claim that buckwheat, mustard, and rape are immune. Many at- 

 tempts have been made to devise some reliable method of destroying 

 wireworms. Some vears ago Professors Comstock and Slingerland of the 

 Cornell Agricultural Experimental Station and Professor Forbes of the 

 Illinois Station conducted a very complete series of experiments extend- 

 ing over a number of vears, and found that insecticides were practically 

 of no value. Thev ascertained, however, that certain cultural operations 

 were valuable in destroying large numbers of the transforming pupae and 

 adults before they emerged from the cells in the ground. It wae de- 

 termined that these pupae and adults wintering in the piipal cells were 

 very sensitive to disturbances such as late ploughing produces. Plough- 

 ing infested or suspected sod land twice — once in August with a good 

 harrowing a week later, and again in late September or October — wiW 

 break up many of the pupal cells and expose the beetles to conditions 

 during the winter which they cannot survive. 



This cultural process, however, ^vill not interfere to anv great extent 

 with the immature wireworms, or those in the grub stage. When a sod- 

 land is broken there will naturally be wireworms in different stages of 

 development, some in the first year larval stage, some in the second year, 

 and others readv to pupate. Onlv those ready to pupate \vill 

 in all likelihood be killed by the fall ploughing. In the follow- 

 ing season how^ever the voung grubs are grown rapidly, and if the dy- 

 ing roots of the sod furnish sufficient plant food they will not do much 

 feeding on the roots of the new crop, but they Avill be more injurious the 

 year following. Nov/ certain crops, such as, clover, barley, wheat and 

 rye, are not so liable to attack as are corn, potatoes, miangels, oats; 

 hence they are better adapted to follow sod. Clover can be sown witii 

 barley or r\^e and ploughed down after a cutting has been taken. 'this 

 may be followed bv corn or roots. Such a rotation will gradually exter- 

 minate the wireworm.s, and furnish crops that give a good yield. 



Lachnosterna fusca— with the grub and pupal stages. 



