BUREAU OF ENTOMOLOGY AXD PLANT QUARANTINE 59 
methods of pea-weevil control. The utilization of a bonier trap crop and the 
plowing under of these border plantings prior to the time the main plantings 
blossomed have given encouraging results in the control of this pest. Experi- 
ments indicated also that dust mixtures containing rotenone may be useful 
in the control of the pea weevil, particularly in crops of high-quality peas. 
Biological studies disclosed that in Idaho the pea weevil is unable to survive 
winter temperatures below approximately — 20° F., thus indicating a limitation 
of its distribution as an economic pest. 
The pea aphid caused heavy losses to pea growers in many of the major 
producing districts of the country, particularly in Wisconsin. Now York, and 
Ohio. Encouraging results in the control of the pea aphid were obtained in 
1935 with sprays containing derris, and special held experiments were con- 
ducted with derris sprays and derris dusts in California. Florida, and Virginia 
late in the winter and in the spring of 1036. The results of these field tests 
indicated that derris sprays were effective in controlling the pea aphid and that 
•under favorable conditions insecticides containing rotenone. the active ingredi- 
ent of derris and cube, had a residual effect that protected the treated plants 
"from severe damage for an extended period after treatment. In general it was 
determined that sprays or dusts containing nicotine have a more rapid action 
against the pea aphid than insecticides containing rotenone but that the latter 
have a much longer residual effect. This residual effect of rotenone-containing 
insecticides against the pea aphid as observed in field tests was substantiated 
by laboratory studies. Continued field work late in the spring of 1936 demon- 
strated that a derris dust containing a specially prepared spreading agent 
yielded results comparable to those from a derris spray, the dust being pre- 
pared by atomizing a sodium oleyl sulphate into the derris-dust mixture while 
it was being revolved in a steel-drum ball mixer. 
Studies on the biology and control of the lima bean pod borer in California 
liave shown that this pest can be controlled with cryolite, but before this 
material can be generally recommended to the grower the possibility of danger 
from residues will have to be determined. As a possible aid in control, para- 
sites from the eastern part of the United States were liberated, during the 
spring of 1936, in California fields infested by the lima bean pod borer. 
POD BORERS IN PUFRTO RICO 
Biological and control studies were made on three species of pod borers that 
commonly attack all types of edible beans in Puerto Rico and that have greatly 
handicapped the commercial production of these crops on the island. Tests 
with various compounds and dilutions of arsenicals, fluorine compounds, 
pyrethrum. derris. and organic thiocyanates indicated that fluorine compounds 
gave the best results but that the use of insecticides containing this element 
was likely to lead to the presence of harmful residues on the market product. 
Consequently none of the insecticides tested to date can be recommended for 
use against the pod borers. Biological studies disclosed that the varieties of 
Deans characterized by relatively smooth pods were not infested by pod borers 
to so great an extent a< varieties bearing pods covered by relatively heavy 
pubescence. Investigations are being continued to determine whether this fea- 
ture may be used to advantage in the control of these pests. Field observations 
indicated that one of the species of pod borers was more numerous in beans 
when this crop was interplanted with corn than when it was grown alone. It ap- 
peared that the shade afforded by the corn exerted some influence in inducing 
a concentration of pod borer adults, since other fields of beans grown under 
directly comparable conditions, but not interplanted with 'corn or other 
companion crops, were found to be relatively free of infestation. 
TOMATO INSECTS 
The tomato pinworm has continued to be a serious pest in southern Cali- 
fornia, but biological studies have revealed possible ways of control. Such 
studies have also shown that contact insecticides, including nicotine sulphate 
or a light Oil, have caused an appreciable mortality of the tomato pinworm in 
its leaf-mining stages. Stomach poisons, excepting those containing fluorine, 
have given unsatisfactory results when directed against the larval stages. Ex- 
tensive held studies have demonstrated that much of the damage from the 
tomato pinworm may bo avoided by discontinuing the present practice of piling 
