ENTOMOLOGY AND I'LANT QLAKANTINE 
7 
pounds per acre of greensand marl, which is promising for use in soils to 
overcome or reduce arsenical injury to plants, did not significantly modify the 
iusecticidal action of lead arsenate within 30 days after application. Further 
studies of the use of lead arsenate in various types of soil from dirterent locali- 
ties have shown that the character of the soil has a considerable iniluence on 
the eifectiveness of the lead arsenate treatment, but that l.Huu pounds per 
acre, as at present recommended for nursery treatment, is adeipiate in most 
soils usually encountered. iSome modincation of recommendations for certain 
soils may, however, be necessary. 
A large number of females of the imported hymenopterous parasite Tiphia 
vernalis Koh. have been collected in the held rrom well-established colonies 
and recolonized in other localities. During the early summer of 1937, 162 
colonies, totaling 16,553 females, were placed in New Jersey, Pennsylvania, 
Delaware, Maryland, New York, and the New England States. With colonies 
that were established in 1033, parasitizations as high as 58 percent have been 
found. Among the imported parasites, this species appears to be by far the 
best adapted to the biology of the Japanese beetle. 
The introduced parasitt> Tiijhia poijiiliavora lioh. is well established in many 
localities, and during the summer of 1936 field-collected females to the number 
of 4,818 were recolonized at 44 points in New Jersey, Pennsylvania, and Dela- 
ware. It has been found that a number of adults of this species have not 
emerged until the second or third year following that in which the cocoons 
were formed. The form of T. popilUavora first introdticed is, unfortunately, 
rather poorly synchronized with its host in the Moorestown, N. J., area. Spe- 
cial attention has therefore been given to a Korean strain of this parasite, 
which emerges later, at a time much more favorable to parasitization. During 
19L.6 nine colonies of this strain were liberated in New Jersey and Penn.sylvania. 
Further studies have been made of the diseases attacking the immature 
stages of the Japanese and Asiatic beetles in the soil. Examinations in the 
field at frequent intervals during the season showed in the early spring a low 
percentage of diseased grubs ; the proportion increased rapidly to a peak of 36 
percent late in June. The disease rate fell rapidly as the new brood of larvae 
developed, then rose to a maximum of about 13 percent in September, and fell 
off again as cold weather came on. Observations on field plots in which types 
A and B milky diseases were artificially introduced in 1935 indicated the estab- 
lishment of the disease with spring introductions, the disease rate increasing 
to as high as 44 percent by June 1936. Similar plots started in the fall of 1935 
indicated that fall is not a satisfactory time for introducing a disease organism, 
because of falling temperatures and unfavorable v/eather conditions. 
Material of Tiphia sternata Park, a parasite of the Asiatic garden beetle, 
was received from the Division of Foreign Parasite Introduction and increased 
in the laboratory for further colonization. Fourteen hundred adult females 
of this species were liberated at five centers in I'ennsylvania and New Jersey. 
At least a few of this species passed the winter of 1936-37 successfully, as 
evidenced by the recovery at Palmyra, N. J. T. ascricae A. and J. was like- 
wise recovered in the spring of 1937. 
In order to keep in touch with the progress of the Japanese beetle in the 
more recently infested areas and to determine its behavior under new condi- 
tions, as a basis for studies of control measures in connection with efforts to 
retard its spread, a new field laboratory has been established at Salisbury. 
N. C. For the present the work deals primarily with the biology, food plants, 
and behavior of the beetle under conditions in the outer zone of spread : this 
is to be followed as soon as feasible by experiments with the control of the 
insect under the new conditions. 
FRUITFLY INVESTIGATIONS 
The research work on fruitflies has been continued as in the iiast in the 
]ab<»rat()ries in ^Mexico City. Honolulu, M;iynguez. P. U.. and the Canal Zone. 
In ^Mexico work has been done on the sterilization of fruit by refrigeration 
to guarantee its freedom from living eggs and larvae of the Mexican fruitfly. 
Studies at 34° to 35° F. resulted in adults emerging after 16 days of exposure. 
Puparia were formed by larvae which had been exiK)sed for 17 and for 18 
days, but no adults emerged from these puparia. The results indicate that the 
