BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 67 
that the margin of safety between an effective dosage and plant injury 
is narrow. 
Naphthalene as a soil fumigant was tested as a control for wire- 
worms in tobacco land near Windsor, Conn., and the indications from 
this and other practical experiments are that the soil types and tem- 
peratures at the time it is necessary to treat the land will limit its 
effective use in the Eastern States. 
The establishment of a control program to protect raspberries 
from infestations of the raspberry fruitworm and blackberries from 
damage by the red berry mite in the Puyallup Valley of Washington 
has assured the successful production of raspberries free of the fruit- 
worm, and the protection of blackberry plantings from injury by the 
red berry mite. The control of the raspberry fruitworm is effected 
by timely applications of a dust mixture containing 1 percent of rote- 
none derived either from derris or cube. Proper use of oils and of 
lime-sulfur sprays will protect the blackberry crop from the red 
berry mite. 
An outstanding feature in the ornamental-plant field was the suc- 
cessful application by growers of gladiolus, both commercial and home 
gardeners, of the tartar emetic and brown sugar spray formula which 
has been in the process of development during the last several years. 
Experimental work this year showed that this spray may be cheap- 
ened without reducing its effectiveness by using only 2 pounds of 
tartar emetic to 100 gallons of water, instead of 4 pounds as has been 
recommended heretofore. 
A spray of derris, pyrethrum, and sulfonated castor oil continues 
to be the most effective material tested as a treatment for the red 
spider infesting greenhouse cucumbers. A tartar emetic spray con- 
sisting of 2 to 3 gallons of glycerin and 2 to 4 pounds of tartar emetic 
per 100 gallons of water was also very effective against the red spider. 
Indications are that tartar emetic sprays may be useful also against 
the orchid thrips and the flower thrips. The results with methyl 
bromide as a greenhouse fumigant against the red spider and the 
Mexican mealybug were variable, and no conclusions as to its actual 
usefulness can be drawn at this time. 
High populations of the beet leafhopper occurred in southern Idaho 
and the San Joaquin Valley of California. Overwintering forms of 
the leafhopper were found in April in the Billings, Mont., area at 
16 of the 21 locations examined. This confirms the findings of 1936 
and 1938 and definitely shows that this insect can survive certain types 
of winter in the Yellowstone Valley of Montana. 
In a study of the insects affecting seed beets in southern Arizona 
a direction correlation was found between the numbers of Lygm spp. 
present on the seed stalks and the percentage of nonviable seed pro- 
duced. Cage studies showed that beside the species of Lygus, Say's 
plant bug and another plant bug, Thyanta custator (F.). common'to 
the area were capable of reducing the percentage of viable seed and 
also the weight of the seed per unit volume. The quantity of seed 
produced was not reduced by these insects nor was the percentage of 
small seed increased. Aphids did not affect the viability of the seed 
but apparently reduced the quantity, while the false chinch bug, num- 
bering up to 500 per plant, had little if any effect, either on the plant 
or on the seed produced. 
