BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 49 
INSECTS ATTACKING SUGARCANE AND RICE 
Although the degree of infestation of sugarcane by the sugarcane borer was 
subnormal during 1935, a careful survey indicated that the loss for Louisiana 
due to this insect was approximately .$1,400,000. Three years' experiments on 
the effectiveness of the egg parasite Trichogramma minutum in controlling the 
borer have been completed and the work has been discontinued. The results 
indicate that, contrary to statements widely made, this parasite is not effective 
in reducing the number of borer eggs present, in increasing the percentage of 
parasitization over that occurring naturally, or in increasing the total tonnage 
of cane or total yield of sugar. Importations of two parasites of the sugarcane 
borer that are of importance in controlling this pest under Puerto Rican and 
South American conditions have been made into the Florida and Louisiana cane 
sections, and a large colony of one of the effective European corn borer parasites 
was released in Louisiana for test against the sugarcane borer. Observations 
on relative susceptibility of cane varieties to borer attack have indicated that 
there is a consistent difference in degree of infestation between certain new 
varieties, and that the moths exhibit a preference for certain varieties for 
oviposition. Studies on the sugarcane borer as a pest of corn in Texas have 
indicated that certain varieties, such as Reese Drought-Resister, Surcropper, 
and Mexican June, are tolerant of borer attack under conditions occurring in 
eastern Texas. A valuable method of control through regulating the planting 
date of corn has been developed for this area. Complete control of the sugar- 
cane borer in rice has been obtained through dragging and flooding the stubble. 
Two new aphid vectors of the important mosaic disease of sugarcane have 
been discovered, and studies are under way to determine the relative importance 
of the various vectors and the relationship between their abundance and the 
presence of their wild hosts, and with the occurrence of ants which may be 
responsible for the distribution of the aphids. 
It has been determined that the rice stinkbug (Oebnlus pugnax F.) is respon- 
sible for a large proportion of the injury to the rice kernels known as "pecky 
rice", which resulted in an estimated loss to rice producers in 1935 of between 
$400,000 and $500,000. Other insects that have been tested have not been 
implicated as a cause of this condition. 
SUGARCAXE INSECTS IX PUERTO RICO 
Investigations on vectors of sugarcane mosaic in Puerto Rico verified the 
fact that Aphis ma id is Fitch is a very efficient vector of mosaic and confirmed 
preliminary results in the United States indicating that the aphid Hysteroneura 
setariae Thos. also transmits the disease. A sedge aphid, Carol inn in cyperi 
Ainslie, was definitely shown to be a very efficient vector of mosaic although it 
is not definitely proved that it is of importance in transmission in the field. 
The insect and its host, however, are very common around the canefields of the 
island and present at all times of the year. Evidence of ability to transmit 
the disease was also obtained with Aphis nerii Kalt. An improvement in the 
technique of transmission, which may be of value in other studies, was worked 
out in which seedling plants were used with distinct advantage over previous 
methods from the standpoint of convenience, ease of handling, and more rapid 
appearance of the mosaic symptoms. An extensive survey was made of the 
insects in and surrounding canefields that might be of importance in disease 
transmission. 
INSECTS ATTACKING FORAGE CROPS 
Low infestations by the alfalfa aphid have hampered the work in Kansas on 
aphid reaction to various varieties of alfalfa, but satisfactory progress has 
been made in California where resistant selections of alfalfa have been sub- 
jected to severe test; some of these have maintained immunity or a high degree 
of resistance and are being used as breeding stock. A study of climatic condi- 
tions governing aphid outbreaks in California has been completed. In Oregon, 
field plots of vetch and Austrian peas seeded after October 7 escaped Infestation 
by aphids and were free of Infestation as late as the following April. Regu- 
lating the planting date may afford a means of escaping commercial damage 
from these pests. A marked variation between vetch varieties in susceptibility 
to aphid attack was indicated by cage tests. 
101897— 3G 4 
