-804- 
in the entire area.. Erom observations it is known that a snail population of 
Mexican .fruit fly developed last summer in northeastern Mexico,- and this, is no 
doubt, reflected in the continued absence of flies from the citrus groves, in 
Texas during the present season. (P. A, Hoidale, Bureau of Entomology and Plant 
Quarantine, U. S. D. A.) 
BEET LEAEHOPPER.— September surveys of representative summer breeding areas 
in southern Idaho in 1940 showed the largest fall population of beet leafhoppers 
recorded during the last 4 years. The acreage of Russian- thistle, the most 
important summer breeding host, was below normal but generally in good condition 
with very little premature drying. Pall surveys in the Sailor Creek sagebrush .. 
area, one of the important overwintering, and spring breeding areas, showed the 
largest late-fall population of beet leafhoppers since 1937* Above-normal 
temperature and excessive precipitation in September 1940 were very favorable 
for fall germination of the fall and winter host plants of the beet leafhopper 
throughout southern Idaho, This early fall germination occurred before the 
summer host plants had matured or were killed by frost; consequently, there was 
no break between the summer end fall host-plant sequence... The winter of 1940— 4l 
was, in geheral, comparatively mild with a slight deficiency in- precipitation. 
The lowest temperature recorded was 1° below zero, which occurred at a tine, when 
the soil was protected by a; blanket of snow and indicated that weather condition 
were favorable for survival of the beet leafhopper and. its winter host plants. 
Spring surveys in the spring breeding areas showed the largest population of 
overwintered beet leafhoppers recorded since 193&* Excessive precipitation in 
April added sufficient soil moisture to stimulate growth of the widespread and 
abundant spring- breeding host plants. The number of leafhoppers in the spring 
movement in 1941 was- approximately two-fifths larger than. f in 193 ®» 17 times 
'larger than in 1939* and one- third larger than in 1940. Surveys of commercial 
beanfi.elds in July showed that curly top injury to beans ranged from 1.0 to 
59*75 percept, with an average of 12,88 .percent in the garden varieties grown 
for seed and from 0 to 58,25 percent, with an average of 10.22 percent in the 
Great Northern, a dry-bean variety groim extensively in southern Idaho. Fall 
populations of the beet leafhopper in southern Idaho in_194l were the lowest, 
recorded since the institution of the extensive fall population survey in 1934, 
This was due in part to the lowest "recorded equivalent acreage of Russian- 
thistle during' the last 7 years. Russian*- thistle,, the most important summer 
breeding host, has been partially or entirely replaced by downy chess, a non- 
host, over large areas. Seasonal study on the development of the beet leaf- 
hopper on summer host plant's shows a gradual decrea&e in leafhopper populations 
since about the middle of July, Dissections of fall-collected females from 
representative summer breeding areo.s showed that the percentage of parasitiza- 
tion ranged from 7*8 to 45.2 percent, with an average of 27.6 percent. Although 
this indicates that parasites were a factor in limiting reproduction of the bee', 
leafhopper, their effect would not be sufficient to account for the gradual .de- 
crease in populations during the latter half of the active season. Patchy germj 
nation of fall and winter host plants occurred about the middle of August as a 
result of 'heavy local showers during the month, but there was .a very poor sur- 
vival of these weeds during September and October. A generally widespread germ: 
nation occurred about October 26 and, as a result, the leafhopper entered the. 
winter of 1941-42 under favorable conditions. (J. R c Douglas, Bureau of .Entv: — 
mology and Plant Quarantine, U. S. D, A,) 
