28 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1952 
staii to form runners and extending through the harvest period: 
The ii-*' of lindane after the first fruits begin to form left a poison 
residue on the harvested fruits and also resulted in off-flavor in such 
fruits. Limited experiments with a lindane emulsion -pray indicated 
that in this form lindane was also effective against the pickleworm, 
but that its use caused the same health and off-flavor hazards as 
lindane dust. Incidentally it was observed that in both the dust and 
spray form lindane was effective against encumber beetles and the 
melon aphid on cucumbers and squash. Experiments with various 
insecticides less toxic to warm-blooded animals, including sabadilla, 
nicotine, rotenone, aUethrin, pyrethrum dusts, and a TEPP spray, ap- 
plied to cucumber plant- after the fruits began to form, -bowed that 
none of these materials was satisfactorily effective against the 
pickleworm. 
CEREAL AND FORAGE INSECTS 
Grasshopper Research and Control 
Insecticides protect cotton fields from grasshoppers 
Farm-scale te>ts of the new organic insecticides were made against 
hoppers attacking cotton and other crops on the Blnebonnet 
Farm, McGregor, Tex. This work was done in cooperation with the 
Texas Agricultural Experiment Station. Aldrin, dieldrin, and toxa- 
phene sprays were applied to field margins and pastures near or adja- 
cent to cotton fields. Aldrin emulsion at -2.1) ounces an acre practically 
eliminated all infestations in the early spring. The same results 
were obtained with emulsions of dieldrin applied at the rate of 1.3 
ounces and toxaphene at 1.5 pound- an acre. These tests were con- 
ducted when the nymphs were it) the third to sixth instars. In later 
sprayings during July, such dosages did not give control. However, 
by increasing the per acre dosages of aldrin to 1- to 8 ounces, of 
dieldrin to 2.8 ounces, and of toxaphene to :\ pounds, results were 
almost a- good as those obtained in the spring. Grasshoppers were 
all adult when the later sprays were applied. 
(Grasshopper development synchronizes with abundance of food 
plants 
Studies of the ecology, distribution, and abundance o( range grass- 
hoppers confirmed the L950 findings that the entire range grasshopper 
complex follow- a fairly orderly sequence of hatching, development, 
and egg laying, synchronized with and dependent upon tin 1 develop- 
ment of range grasses, herb.-, and shrubs that serve basic food require- 
ments. This sequence of events is apparently maintained year after 
year, being advanced or retarded within fluctuating limits of the 
weather. These studies assist in the proper timing of surveys and 
eont rol opera! ion-. 
Grasshopper parasites and disease effective in limited areas 
Two grasshopper collections in a locality in Montana showed 94 
and 97 percent parasitization by nemestrinid parasites. Parasitiza- 
tion in the same locality in L950 -bowed a maximum of s " percent. 
