SMALL WORMS BORING IN THE ROOTS 111 



ing the overwintering queens, migrate to it. The whole thing is then 

 covered with canvas and fumigated with carbon bisulphide. Summer 

 colonies are killed by fumigation in the same manner as described above 

 for other species, or by poisoning with dilute arsenic and sweetened 

 water, as described in the chapter on Household Insects. 



The Southern Corn Root-worm {Diahrotica duodecimpundata 0\W .) 



The presence of the southern corn root-worm or " bud- worm " is 

 usually first indicated by an enfeebled growth of the young plants. 

 The leaves turn yellow, or the plant simply fails to make a normal, 

 vigorous growth. If a plant is pulled up and the roots are shaken, some 

 of the grubs will likely be thrown out, and the round holes where they 

 have bored into the side of the main stalk, just below the ground, will 

 be noted. The grubs are about three fourths of an inch long when full 

 grown, are quite slender, smooth, white or light yellow, and have a 

 small brown head. 



The adult of this worm is a small beetle, about one fourth of an 

 inch long, commonly known as the twelve-spotted cucumber beetle. 

 It is greenish yellow in color, and has twelve black spots on its back. 

 It feeds on the pollen or silk of corn, on a great variety of garden 

 crops, especially cucumbers, squashes, melons, and related plants, and 

 sometimes on the young heads of various grains or grasses. 



Control of the root-worm in corn is largely dependent on general 

 farming methods. Crop rotation will help to hold it in check, and so 

 will systematic clean tillage. The worms do not infest the roots of 

 cotton, buckwheat, or the smaller grains. Late-planted corn is less 

 liable to attack, and so is corn in well-drained land. Many farmers 

 find it expedient to plant an excess of seed. Remedies for the adults 

 on garden crops are given elsewhere. 



The Western Corn Root-worm (Diabrotica longicornis Say) 



In the Central states the roots of corn are injured by a small, slender 

 worm which mines in the main roots, tunneling here and there, seriously 

 checking the growth of the plant if not killing it entirely. The worm is 



