90 ANNCAL RK PORTS OF DKPAKTMKNT OK AflRICnJl'RE, 1 'J 4 
L5 pounds for 25 minutes grew in this medium. Less than one- 
tenth this amount of heating was formerly thought sufficient to 
destroy all spores of B, lai'cae. 
INVESTIGATIONS OF ABNORMAL DEATH OF BEES IN UTAH 
Field and laboratory investigations were started in May 1940, in 
Cooperation with the Utah Agricultural Experiment Station, to de- 
termine the causes of the abnormal death of adult bees in Utah, 
variously claimed as resulting from insect-control operations, from 
the effects of smelter fumes, or from other causes. The territory 
affected in past years was surveyed and samples of dead bees and 
other materials were analyzed for arsenic. With a few exceptions, 
losses have not been so serious during the current year as in pre- 
vious years, and analyses of bees have shown no outstanding cases 
of excessive amounts of arsenic. 
CAUSES OF SPOTTED BROOD 
Work during 1939 on the causes of spotted brood indicates that this 
condition is caused by irregular laying of eggs, characteristic of 
certain queens, and by a heavy brood mortality principally before the 
fifth day after egg laying. Such factors as population, availability 
of nurse bees to the total amount of brood, pollen reserves, and 
seasonal changes also influence this condition. Mortality varied 
greatly in colonies headed by queens of the same strain, and it is 
impossible as yet to state whether a high or low brood mortality 
is a characteristic of a given strain. 
TESTS OF COMMERCIAL STOCK 
Tests of 13 lines of commercial stock showed pronounced differ- 
ences in production efficiency and queen losses, and indicate that 
the hereditary background of the stock is largely responsible for 
its performance. Honey yields for the different lines ranged From 
60 to 160 pounds per colony above winter requirements. Colony 
yields ranged from 17 to 262 pounds for colonies that did not super- 
sede their queens. The stock giving highest production was from 
the same source as the best stock tested in 1938. Seven of the 
thirteen lines were also compared in 193.S and. for the most part, the 
performances were similar during the two seasons. Queen losses 
amounted to 38 percent, the greatest loss occurring in those lines in 
which surviving queens headed medium to poor producing colonies. 
Four of the thirteen lines lost or superseded from f>0 to 60 percent 
of their queens, whereas two lines had no loss. 
In the spring of 1940, 42 percent of 139 queens shipped in cages 
and introduced into queenleSS packages required 2 to 6 days to 
begin egg laying, whereas queens shipped in packages began laving 
12 to in hours after introduction. The delayed egg hiving experi- 
enced with queens shipped separately probably is due to improper 
feeding during shipment. Delayed egg laying in turn is proba- 
bly responsible for the heavy loss at introduction, which amounted 
to in percent of 267 queens used. 
BIOCHEMICAL DIFFERENTIATION or F] MALE CASTES 
Biochemical investigation of the differentiation between the fe- 
male castes of the honeybee has BflOWn that queens and workers have 
