BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 75 
difficulty. Crude waxes could well be graded according to the class of impurities 
present rather than according to their chemical and physical constants. The 
treatment of crude waxes with dilute oxalic or sulphuric acid appears to have 
little effect on acid number, an important factor in the cosmetic industry. 
"Bloom" on beeswax has been found to he due to a wax component that is 
soluble in wax solvents but not iu dilute acids or bases. Its melting point is 
about '24' C. below that of wax. 
Studies dealing with pollen supplies, brood rearing-, and adult population 
reveal that deficiency in pollen is a major cause of weak colonies. In the 
orange-growing territory in California bees rapidly depleted their artificially 
supplied reserves. In some localities, however, as in the deciduous-fruit areas, 
there is apparently a sufficient held surplus for short periods to permit pollen- 
reserve storage. Laboratory and field tests strongly emphasize that surviving 
populations of overwintered colonies are directly proportional to the quantity 
of pollen stored in the fall, provided all other colony requirements are adequate. 
Preliminary studies indicate that package bees may be established at such a 
time prior to the active season as honey and pollen reserves can be provided in 
sufficient quantities to sustain a colony until a held supply is available. 
Studies in cooperation with the Oregon Agricultural Experiment Station 
reveal a deficiency in bee population in numerous Oregon fruit-growing districts. 
The list of known honey plants includes 128 species. The concentration of nectar 
in certain of these plants ranges in sugar content from 5 to 77 percent. Bees 
were found to be so sensitive to the sugar variation that certain fruit blooms 
were ignored in preference for those yielding richer nectars. Oregon maple 
and mustard in particular are formidable competitors. A similar variation has 
been found between varieties of a species of honey plant — an important factor 
hitherto ignored in pollination studies. 
The bee-breeding work during the year shows definitely the need of finding 
easily recognizable characters that can be used in pursuing studies on inheritance, 
and a search is being made for such characters. Work under way includes a 
study of the inheritance of the yellow scutellum, characteristic of Cyprian bees. 
A distinct yellow coloration of mouth parts, apparently a mutation, has been 
discovered, and an effort is being made to obtain a homozygous strain. 
Apparently this character is recessive. 
Samples of Tahitian, Cyprian, Carniolan, and selected crosses obtained by the 
Watson method are on hand and await analysis. Material improvements have 
been made in the microsyringe used for making inseminations, and a glossometer 
has been devised which enables a quick reading to be made of the usable tongue 
length of colonies. 
Studies are being made in commercial queen yards to determine the reasons 
for losses of queens during rearing and mating. Such factors as the effect of 
size of nucleus, physiological aspects of the number and age of worker bees, 
kinds and quantities of food available, and the final development of queens are 
being investigated. 
Over 880 packages of bees have been under observation this spring in apiaries 
of commercial cooperators in a study of the supersedure of queens shipped in 
packages. Over 200 queens shipped separately and introduced into colonies in 
the fall for requeening are also under observation. A considerable variation has 
been found between the stocks of different shippers, indicating thai an impor- 
tant part of the problem may rest with the conditions affecting the production of 
queens. 
INVESTIGATIONS OF INSECTS AFFECTING MAN AND ANIMALS 
SCREWWORMS AND OTHER BLOWFLIES 
Research on the biology and habits of screwworms and other blowflies and 
on the development of more economical and effective control methods against 
these posts has been continued. Data obtained as to the effect of climatological 
factors on the development of screwworm flies have made it possible to define 
hibernation areas more accurately than heretofore and to determine factors 
which contribute toward bringing aboul outbreaks. With this information as a 
guide, it will be easier to recommend where control work should he concentrated 
to give maximum results and retard dissemination of the dies, studies have 
shown that the hies can travel a distance of at least !i miles. Natural migra- 
tion Of the flies in 1936 from areas in Texas, where they overwintered, north- 
