300 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



largely upon the time when the attack of the aphis is made. If the 

 plants are small they may be readily destroyed, while if they are 

 practically full grown the loss of the small rootlets will not 

 materially affect them. 



" No sexual generation of this aphis has as yet been discovered 

 and no eggs have been seen, viviparous reproduction continuing 

 throughout the year except when the cold of the winter tempo- 

 rarily suspends the physiological activities of the species. The 

 winged females, appearing from time to time during the summer 

 and fall, serve to distribute the species generally, new colonies 

 being started wherever these females find lodgment and food. In 

 districts liable to injury by this insect it seems inadvisable that 

 beets should be the first crop on new land, or that ground should 



be continued in beets or in any other 

 root-crop after the pest had made its 

 appearance in the field." 



Another plant-louse, called the beet 

 root-aphis*, proved injurious to sugar- 

 beets in Colorado in 1903. They were 

 found " quite generally distributed in 

 the beet-fields in the vicinity of 

 Rockyford and attacking the roots of 

 many weeds." What seemed to be this 



FIG. 254.-Beet root-aphis s P ecies was ver y abundant upon the 

 (Tyckea brevicornis Hart) : roots of the common garden purslane, to 



r^f fessrsiSS: which * was very injurious - Near Fort 



(After Garman.) Collins a badly infested field of sugar- 



beets was also seriously damaged. 



No practical means for controlling these pests seems to have 

 been recorded, so that in case of injury the entomologist of the 

 State should be consulted. 



White Grubs, Wireworms, and Cutworms 



Fortunately for the sugar-beet farmer the worst insect ene- 

 mies of that plant feed upon the tops, and very rarely do we hear 

 of serious damage being done the roots. In the East most of the 

 damage to the roots is done by those familiar old farm-thieves, the 

 white grub, -the cutworm and the wireworm. As a general rule 



* Tychea brevicornis Hart. 



