44 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1939 
work provided 50,495 man-days of employment. The maps are used 
in carrying on ft&6# eradication and greatly increase the efficiency of 
conl rol work. 
IMPROVEMENT OF CONTROL PRACTICES 
Prior to L938 the primary objective of the work in developing 
methods for blister rust control for the western white pine region 
was the chemical eradication of Ribes. Now, the chief interest is in 
the possibility of aiding !?'i><s suppression through forest-ma 
men! practices. This shifl parallels the transition gradually taking 
place in the control work for the western white pine region which 
culls for increased attention to rework problems. The most urgently 
needed data seem to be those related to the regeneration s on 
areas where these plant- were removed by mechanical or chemical 
means. Observations, therefore, arc being made in cooperation with 
the Forest Service on the effect of differenl methods of -land im- 
provement on the regeneration of Ribes. The germination of Ribes 
seed and the growth rate of established plants arc being given atten- 
tion as foundations for interpreting record- of large-scale eradication 
and checking work. 
In the sugar pine region preliminary tests of a horse-drawn Ribes 
grapple for eradicating Ribes roezli are encouraging. Also a bull- 
dozer was planned and tested for working heavy concentration- of 
mature upland R. roezli. These tool- gave sufficient promise to jus- 
tify further developmental work. Data further indicate thai dyna- 
mite will be cheaper than chemicals for certain large Ribes in non- 
rocky sites. Where bushes are rooted among large boulders or in 
rock crevices, the use of oil or dry chemical is a more practical and 
economical method. 
CEREAL AND FORAGE INSECT INVESTIGATION - 
WHITE-FRINGED BEETLE 
Studies of the white-fringed beetle {Pantomorus h><-coloma 
(Boh.)) in 1938 rendered certain the fact that this insect normally 
produces but one generation annually. Physical development and 
rate of reproduction of this insect are governed importantly by the 
land of plant food it obtains. Among the cultivated crops peanuts 
are found to be the most favored food plant. The average number 
of eggs laid by this insect when feeding on peanuts was L,531, hut 
the maximum number laid by any one beetle was 2,418. This will 
illustrate the extreme power of reproduction possessed by this pest 
The fallowing of large area- of farm land as a control nica-un 
resulted in preventing. oviposition of the hectic and caused a great 
reduction in larval population subsequently. Experiments in the 
rotation of crops indicated thai much heavier populations of the 
beetle followed peanut-, and corn intercropped with velvetbeans, 
respectively, than was the case with pure stands of ecru or cotton. 
In I he held adults were found to (wA on L32 Species of plant- ami the 
larvae or grubs on 1 75 species. 
GRASSHOPPERS 
Observations of grasshopper populations on eighteen intensive 
long-period Study area- which are being conducted by the Bureau 
