GRAPEVINE ROOT WORM 15 



LIFE HISTORY 



The life history of this insect may be summarized as follows: 

 The winter is passed by the nearly full grown grubs in oval 

 cells in the soil, and so far as our observations go the great 

 majority of them occur from 10 to 12 inches below the surface 

 and mostly near or in the subsoil. On the approach of warm 

 weather, the grubs work upward, probably early in May in most 

 years, and are then mostly within a few inches of the surface 

 and usually within 15 to 24 inches of the stem of the grapevine, 

 though some, and occasionally large numbers, may be found near 

 the middle of the row. Usually very little feeding is done 

 in the spring. The transformation to the pupa occurs in normal 

 seasons from about June 1 to 20, the adults issuing approxi- 

 mately two weeks later or from about June 20 onward. The 

 great majority of the beetles appear the last of June or early in 

 July, though some do not emerge till the last of the month and 

 in rare instances much later. A pupa was met with Aug. 15, 

 1902, and the adults have been found in New York vineyards as 

 late as September and even in October. The latter are probably 

 from belated larvae. The eggs are mostly laid in July and August 

 under the loose bark of last year's wood and require a period of 

 about two weeks to hatch. The young grubs make no attempt to 

 crawl down but drop, and working under the loose soil make their 

 way to the small feeding roots, where under favorable conditions 

 they grow rapidly and after increasing considerably in size attack 

 the larger roots, eating away long strips of the bark [pi. 1, fig. 5] . 

 The latter, when a large number of grubs are present, may rest 

 simply on a bed of borings. Many of the grubs attain nearly full 

 size the latter part of August or early in September. Late in the 

 fall the larvae descend to considerable depths, as previously noted, 

 construct their oval cells and pass the winter within them. 



Habits of the beetle. The habits of the beetle are of special 

 interest because it is practicable to collect these insects and thus 

 in a large measure prevent egg-laying and consequent damage 

 from the grubs. Professor Webster states that the beetles 

 normally begin to appear in northern Ohio about June 20. This 

 agrees closely with our observations. The season of 1902 was 

 remarkably late, and very few beetles were observed previous to 



