

jo 
. data: bearing on this point, derived during May from three sources, the season~ 
al, periodic, and cooperative surveys. Those of the seasonal series of sur~ 
veys are empirically summarized in the right-hand section of the: table below, 
and data for 1932-1933 is given in the left-hand section for comparisons. 
‘Fluctuations in Japanese beetle soil populations 

Average population per square foot 
Period 1932-194 
* ) NeJe 3 Pas :iGeneral: N.oJ. : Pas - : General 
hawt : : 3 : Ra Pee nee 
; Number +; Number : Number ; Number ¢. Number ; Number 
Septe 1 to Nove 30 -- 3: 0660 : 1567 ¢ 11.9 : 669: Ger wire 
Dece 1 to Feb, 28 --: rs Pp tleOns tara os oy FUMES Tia: 3 
' Mare 1 to Apre 50 == 3 Pi) puel abi 1064 3 2° : Te? 3 fs 
May, 1 to 15 ~-+--~- Ru isGe Gta iinitlela’s <.09tu & Tay : “ig 
16 to Fl mnncmmm 37d t UNe2 2 903 2 509 Feb 66 
: ; : : : : 

According to these figures the soil population represented in the last 
half of May averaged about 17 percent less than during the fall of 1933, and 
-27 percent less than the brood represented. late in May of 193%. The reduce 
tion of 17 percent is not interpreted as indicating an unusual winter mortalitye 
It was not greater than that found in 1942-1933. _ 
‘ Data on fluctuations in soil populations secured during May in connec~- 
tion with series of surveys show that the general average for the 10 stations 
examined was 9.9 Jarvae per square foot in the fall and 9.2 in May--a general 
seasonal decrease of roughly 7 percent. . In the report for April 1944.it was 
noted that at locations visited during that month a decrease of 3 percent. 
during the winter was founde Such reductions are usual in winters of normal 
temperatures. The spring surveys are now completed and the evidence bears 
out the opinion expressed earlier that the cold weather of the past winter 
has not caused any appreciable reduction in the grub population of the 
Japanese beetles 
A series of surveys was carried on in the fall of 1933 and another in 
the spring of 1944 in cooperation with the New Jersey Department of Agricul~ 
turee These were confined to the heavily infested areas in Cumberland and 
Salem Counties and were made largely in pastures. Here again, there is no 
indication of a winter reduction. The average grub count in October 1943 
was 13.9 per square foot and in May 1944 it was 14.5 per square foote The 
apparent increase is attributed to the greater difficulty of finding grubs as 
they moved downward in Octobere , 
Jap beetle larvae abundant in cultivated fields in southern New: .. :? 
Jerseye+-Ie Me Hawley and I. Ne Dobbins, of the Moorestown, NeJe, laboratory, 
report on larval surveys mde in fields in the heavily infested area in 
southern New Jersey to determine the grub abundance under a variety of crop- 
