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Usual ly collections were made "by from 2 to 4 collectors between 
7 2 30 and 11:30 p.m. , although later in the season the flight might not be- 
gin until about 8:20 p.n. Sometimes, when small flights had occurred, 
the plants were well covered by the collectors before 11:30 p.m. A total 
of 71 collections were made from 25 groves between April 26 and. July 29 . 
Very few beetles were found late in June in other thaaethc Gays Mills area 
and no collections were made after July 1, except at Gays Mills. The lo- 
cation of the groves and the number of collections made' in each were as 
follows; Dane County — Dane, 5 collections; faunakee, 1* Oregon, 1; Blue 
Mounds, 4; Columbia County — Lodi (Camp Perry), 3; Leeds, 4; Poynette, 2; 
Walworth County — Whitewater, 1; Racine County — Racine, 1; Kenosha County — 
Kenosha, 1; Fond dU Lac County — Ripon, 1; Waushara County — Hancock, 1; 
Lafayette County— , 6 in 2 grovos; Iowa County — Linden, 3; Hock 
County — Edgerton, Grant County, Boscobel, 2 in 2 groves, Wyalusing, 1; 
Crawford County — Gays Mills, l6 in 1 grove and l4 in 5 other nearby groves. 
Figure 1 shows these localities. 
The Gays Mills area which was studied most intensively. differed from 
the other areas mainly in the absence of bur oak, the scarcity of Phyllo - 
phaga hirticula (Knoch) and predominance of P. rugosa (Melsh. ). To include 
the collections from this area with those from other parts of the State 
would bias the averages on which the relative populations of the various 
species throughout the southern part of the State are based. For this 
reason, the collections from the Gays Mills area are, for the most part, 
considered separately from the others, 
Nuribei 4 of Beetles and Species Collected 
A total of 24,219 beetles, belonging to 18 determined and 1 unde- 
termined species, were taken. Although this number exceeds slightly the 
total collected in the previous 3 years, the beetles did not seem so num- 
erous as in 1935 (the previous flight of "A Brood"), except in Lafayette 
and Iowa Counties, where Phyllophaga hirticula Knoch was very abundant. 
Of the 24,219 beetles, 9*759, °r 40 7 29 percent, were P. rugosa (Melsh.); 
6,702, or 27 . 67 , percent were P. hirticula ; 4,S45.or 20.00 percent, were 
P. fusca (Froel.); and 73^, °r 3*05 percent, wore P. prunina (Lee.). Col- 
lectively, these 4 species comprised 91*02 percent of the beetles col- 
lected. The first 3 of these species were most abundant, in the same 
order, in 1935 but in that year P. tristi3 (F.), rather than P. prunina 
was fourth. Of species having a 3 - year life-cycle, the same 3 species have 
been most abundant each year since 1935 * inclusive, except in 193 &* when 
P. hirticula was rare. In 193& £• tristis , which has a 2- year cycle, was 
extremely abundant and greatly exceeded all other species in numbers. Be- 
cause of this high population in 193 &, a heavy flight of this species would 
have been expected in 193^, but field diggings had shown that P. tristis 
had laid very fey; eggs in the extremely dry soils of that year and very 
few grubs of that brood were found in the years following. Table 1 shows 
the numbers of beetles of each species taken and the percentage of tho total 
comprised by each. 
—'In this case the grove was a short distance northwest of Edgerton 
in Done County. 
