ENTOMOLOGY AND PLANT QUARANTINE 
3 
Cooperative extension work in entomology was supervised under the direction 
uf the Bureau and the Office of Cooperative Extension Work. 
Approximatelv 222,6(X) copies of publications were distributed, exclusive ot 
those sent out on regular mailing lists and miscellaneous mimeographed ma- 
teriaL 
FRUIT INSECT INVESTIGATIONS 
APPLE INSECTS 
lu the search for insecticides which may be substituted for lead arsenat»> 
in the control of the codling moth, approximately 250 new compounds, chiefly 
organic materials supplied by the Division of Insecticide Investigations, weiv 
given preliminary test at the Beltsville, Md., laboratory. In practically all 
cases the results were so poor that the materials were eliminated from further 
consideration ; a few warrant further laboratory study. 
Certain nicotine combinations, particularly nicotine-bentonite, have continued 
to give encouraging results in field and laboratory, and one form of this ma- 
terial is being tested on a semicominercial scale in orchard plots of about 2^2- 
acres each in southern Indiana. A number of growers have been very much 
impressed by the results with the nicotine bentonite and are using it on portioiH 
of their acreage. If found practical, this material will be especially useful on 
early varieties such as the Yellow Transparent, which does not lend itself very 
readily to the washing process for residue removal. The high cost of nicotine- 
bentonite is, in part at least, offset by additional benefits in the control of other 
in.sects and by the more favorable effect on the tree than results from the use 
of lead arsenate. 
In the Pacific Northwest phenothiazine has continued to give outstanding 
control of the codling moth, but the difficulties formerly pointed out have not 
yet been overcome. The chief disadvantage is the serious skin irritation suffered 
by some of the men doing the spraying, and by the men who later work in 
the trees thinning or harvesting. A minor disadvantage is a more or less un- 
favorable effect on the coloring of the fruit. In the East and Middle West 
the results with this material are still irregular but have offered sufficient 
encouragement to justify further work. 
At Vincenncs, Ind., more use is being made of a "field-laboratory"' method 
of testing insecticides. Field plots are laid out and sprayed as usual, and at 
intervals the apples are taken to the laboratory and artificially infested with a 
known number of newly hatched codling moth larvae. The experiments are 
thus independent of the natural infestation, which is often very irregular within 
the same orchard. This method gives a running picture through the season of 
the relative effectiveness of the materials tested. The detailed information 
resulting from the use of this method is of great value in supplementing that 
t)btained by the usual methods of field testing, in which the results are judged 
largely by the condition of the fruit at harvest time. 
The program of recolonization of the codling moth parasite Ascogaster quad- 
ridentatus Wesm. has been completed. A large number of living adults of the 
eastern parasite Phnnerntoma tihialis Hald. have been .sent to Parma, Idaho, 
for lilterntion in an orchard which is being used at that point for a parasite 
project in which this Bureau is cooperating with the Idaho Agricultural Experi- 
ment Station, and a small colony of the native parasite Aenoplex cnrpocapsae 
Cushm. has been sent to the same place. The European codling moth parasite 
Ephialtcs cxtcuftor Tasch. was received in small numbers from the Division 
of Foreign Parasite Introduction and was propagated in the laboratory, and 
small colonies were liberated in New Jersey and Idaho. Studies of the cocoon 
parasite A. carpocapsae showed that breeding nearly ceases during July and 
August, but becomes normal again in September. After being quite abundant in 
certain orchards in southeastern Illinois in 1985, this species virtually dis- 
appeared from the same orchards in 1930. 
The program of distribution of AphcIinH.<< mnli Hald.. a parasite of the 
woolly apple aphid, to the Western States in which this effective beneficial 
insect was not already present, has been completed. 
Studies of the biology and .seasonal history of the pear tlirips in the North- 
west have indicated that the time of emergence from hibernation, with refer- 
ence to the blooming period, varies considerably from year to year; and this 
makes the proper timing of spray applications difficult, although, when proi)erly 
timed, applications of nicotine in .several combinations have given very large 
reductions in the lo.sses caused by this insect. Studies of the part played by 
