'■ifilp 
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Discussion 
These studies are important in their relation to the control of 
beetles of the genus Phyllophaga "by spraying their host plants. From three 
seasons 1 work it would appear that the control of the six predominant species 
in southern Wisconsin would effectually solve the June "beetle problem in that 
region. These species are P, rugosa . P. hirticula . P. fusca . P. tristis . P. 
implicita . and P. ilicis' . The first four of these are considerably nore 
abundant than the last two, P. tristis could apparently be controlled by 
spraying oaks, especially bur oak, with an effective insecticide; P, hirticula 
by spraying oaks, especially bur oak, and in some cases hazel and hickory as 
well; P, implicita by spraying poplars and willows; and P. ilicis by spraying 
hazel, butternut, and hickory, P. rugosa and P. fusca were found on a large 
variety of host plants so the spraying of a single species, or even several 
species, might not materially reduce the numbers of beetles of these species. 
P, implicita and P. ilicis have roro 1 y, if ever, been encountered as grubs 
in cur sample diggings in cultivated fields and these species may not be 
important as pests of field cicps. Grubs dug from;pastures f grain stubblo, 
and corn have chiefly belonged to the species £,, rugosa . P. hirticula . P. 
fusca . and P. tristis . although P, futilis grubs are fairly common in Lafayette 
County, and the general destruction of adults of these species apparently 
would solve 'the grub problem* 
There are still many obstacles in the way of spraying trees for control 
of Juno beetles. In addition to the fact that no entirely satisfactory in~ 
secticide for June beetles has been found, there are many tall trees in southern 
Wisconsin and spraying these requires the use of an efficient power sprayer 
equipped with long leads of hose; the host plants are often located in mixed 
plantings near the tops of hills and sometimes at considerable distances from 
water; and the groves where beetles tend to concentrate are often scattered. 
One condition favorable for their destruction, however, is the tendency for 
maximum defoliation to occur where bur oaks are predominant. 
