146 



three acres in extent — the averag-e heig"ht was not more than a foot 

 and a half. The lower leaves were partially dried and the tips of 

 others were fading- and drying- up. In all these injured spots the 

 roots had been g-nawed or eaten, and the root-worms were found 

 sometimes as many as a dozen or eig-hteen in a hill. In much the 

 g-reater number of cases these injured fields were on relatively high 

 and rolling- land, usually, indeed, on the tops of hills where the 

 soil was lig-ht and the g-rowth of the plant comparatively slow; 

 and in most cases these fields were all in corn for the first year 

 after sod. Two instances were observed, however, of the occur- 

 rence of this this root-worm in fields which had been in corn the 

 year before. 



It was difficult to judg-e of the precise amount of injury to be 

 attributed to the root-worms owing- to the fact that they were so 

 frequently associated with other insects affecting- the g-eneral vigor 

 of the plant in a similar manner. White g-rubs and wire-worms 

 were common in some of these fields, and the corn root-aphis 

 {Aphis maid i fad id's) was seeming-ly more injurious at the time 

 than any other insect pest. 



The actual injury to the roots seems to be somewhat charac- 

 teristic and not likely to be mistaken for that of any other insect. 

 The tap-root was certain to be damag-ed if any harm at all had 

 been done, the soft outer tissue of the root being- eaten away down 

 one side in an irregular line which sometimes took a more or less 

 winding- course. Usually only the surface tissue was g-nawed off, 

 but in other cases spots were eaten out to the middle of the root. 

 The larva never cuts the root off or eats it up wholly, as does the 

 white g-rub, and never burrows inside of it like the common corn 

 root-worm. 



General Appearance of the Insect. 



As seen in the field in June this root-worm (Fig. 32) is a small, 

 thick, soft, and fleshy g-rub, an eig-hth of an inch in leng-th when 

 g-rown, with the head white or reddish or brown according to the time 

 since the last molt. The head is hard and smooth, and the top or 

 back of the first seg-ment of the body immediately behind the head 

 — the ore bearing- the first pair of leg-s — is smooth and leathery and 

 of the same color as the head, the rest of the body being- soft and 

 wrinkled crosswise. The only insects likely to occur in the same 

 situation for which this root-worm might be mistaken are very 

 young- white g-rubs; and these are very readily disting-uished by 

 their more slender form, but especially by the fact that the leathery 

 shield behind the head is wanting- in the white g-rub, the first segf- 

 ment being- soft and wrinkled like the others. 



