62 THE SUGAE-BEET WIEEWOEM. 
were being collected. It was suggested also by the different states 
of affairs noted in different fields where various systems of culture 
had been practiced. These observations were carefully made in 
fields aggregating over 600 acres, and daily during a period covering 
about two months. 
Two different methods are practiced by the growers in disposing 
of the beet tops which remain in the field (see PL XX) after the crop 
has been harvested. Some growers leave them in the field to be 
plowed imder and act as a fertilizer, while others use them for stock 
feed. In the latter method, which may be spoken of as clean culture, 
the beet tops are either disposed of by pasture (PI. XXI) or they are 
hauled from the field (PI. XXII). The tops are removed best by 
pasturing either with cattle or sheep. 
The tops which are left for fertihzer are supposed to be plowed 
under, but by the time the land has been harrowed several times, and 
planted, not a few have reappeared on the surface. Then as the 
beetles appear in the spring and enter their secondary hibernation 
they find excellent shelter and feeding places (see PL XIX, fig. 2), and 
most of them remain in the field near the place where they emerged 
and are able to pass this critical period of their fives safely. On the 
other hand, where the tops and old beets have been cleared off, the 
beetles find no place to Ifide, and consequently move to other fields 
in search of shelter. Very few can hide under clods or in the soil on 
account of internfittent rains. 
One illustration of the effects resulting when beets are left in the 
fields will be sufficient, for this same state of affairs was found to 
exist in all the fields examined. 
The beet fields A, B, and C adjoined one another as shown in the 
diagram (fig. 9). At the right of 6^ was a field of alfalfa. In A the 
beet tops had been left in the field to act as a fertihzer; in B and C 
they had been cleared off. During the preceding year the field C 
had suffered from ^rireworm injury as much, if not more, than any 
field in the Compton district. On this account there must have been 
many mature ^\ii-eworms there, and consequently many beetles 
emerging, yet when the beetles were collected in these fields hardly 
any were found in B and (7, and they were taken in A literally by 
thousands. As an experiment, about 50 old beets were scattered in 
the field C, along the line c c. These beets were inspected daily from 
this time on, and found to shelter large numbers of adults, even though 
none had been taken pre^dously in C. Conditions in the other two 
fields remained as before, no beetles, or very few, being found in B 
while ^4 yielded its usual number. 
A simple conclusion can be drawn from these observations. The 
beetles collected only where they could find shelter, and those which 
emerged from perfectly clean fields had either to move to other fields 
