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INTRODUCED NATURAL ENEMIES CONTROL BLACK FLY 
Work on the important cooperative project with the Cuban Department 
of Agriculture, looking to the control of the citrus black fly by import— 
ing its natural enemies from Asia, which has covered two and one-half 
years, was brought to a very successful conclusion the latter part of 
the month of November. This work has been discussed in the last two an— 
nual reports of the Chief of Bureau and in the Official Record of the 
Department (November 6, 1930). C. P. Clausen made the studies, collec-— 
tions, and shipments of parasitic and predacious enemies in Malaya, re- 
turning to this country in June, 1931, with the last consignment of ma- 
terial. The work of breeding and colonization in Cuba was conducted by 
P, A. Berry, assisted by J. M. McGough, and was given personal attention 
by Mr. Clausen for considerable periods in the interval between the two 
expeditions to Malaya and in connection with the final consignment. 
Mr. Clausen found altogether 15 species of parasites and predators at 
tacking the black fly in Malaya and the Dutch East Indies. Of these 6 
were actually brought into Cuba, 4 parasitic flies and 2 predacious 
coccinellids. Only one of the parasitic flies was successfully estab- 
lished, Eretmocerus serius Silv., discussed at some length on page 8 
of the Monthly Letter for November, 1931. Of the two coccinellids, 
which seem to be successfully established in Cuba, the smaller one, 
did well during the dry season but declined during the rainy season. 
The large coccinellid, Cryptognatha sp., bred freely in the Island and 
actually effected commercial control in a few groves, but seems to be 
important only in groves where the black fly infestation is very severe, 
where, in the instances referred to, it eliminated the black fly infes— 
tation in less time than the parasite. The notable immediate and future 
benefit, however, would seem clearly to rest with the parasite, Eretmo— 
cerus serius, which alone bids fair to solve the control of the black 
fly in Cuba, and the same result is anticipated in other sections. In 
addition to the clean-up of the black fly indicated for Cuba, it has been 
possible to establish colonies in Haiti, the Canal Zone, and the Bahamas. 
The Cuban officials are prepared to carry on the necessary work with 
these parasites and have indicated willingness to cooperate in their 
introduction into other regions of the West Indies and Central America. 
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TOXICOLOGY AND PHYSIOLOGY OF INSECTS 
D. E. Fink, who is making studies of the distribution of radioac— 
tive lead arsenate in insect tissue and organs, using the photographic 
method, at Takoma Park, Md., reports: "The evidence, so far gathered, 
from these studies points to the fact that the major distribution of 
radioactive lead arsenate after it leaves the digestive tract is accom— 
plished through the medium of the blood stream. Centers of intense ra- 
diation, * * * are due to (1) the presence of undigested plant tissue 
