766 
MISS ELSIE J. HARVEY ON 
Experiments. 
1. To Discover whether Bees become infected before Emergence from Cells. 
Early in the spring of this year a few frames of brood from a badly affected stock 
were placed in an incubator ; 155 of the bees which hatched out were examined, with 
the result that only the tube on one side in one bee was found infected with the 
parasite. This evidence, as far as it goes, therefore, does not exclude the possibility 
that mites may enter the cells and invade a bee’s body before it emerges from the 
cells, but its rarity, as shown here, would seem to suggest that at best it is only 
an incidental occurrence, and is not one of the regular ways in which infection 
is conveyed. 
2. To Discover the Stage or Stages which occur normally outside the Bee. 
{a) By examination of the individuals in the tubes, in cases where the infection 
had only newly commenced, it is often found that an ovigerous female with a few 
eggs in different stages of development are the only parasites present. This would 
suggest that the migratory stage of the parasite is the fertilised female. In such a 
case migration of the male does not seem to be necessary, although, as is seen from 
the results of the experiments recorded, they leave the body of the dead bee. 
(b) Equal numbers of living and of dead bees were placed in separate petri 
dishes, and these were kept as nearly as possible at the temperature of the hive. 
The dishes were examined microscopically at intervals of from two to forty-eight 
hours. Fifteen such experiments were carried out, with the result that only 10 
mites, all of which were females, were recovered from the living bees : one of these 
was alive and active. As many as 75 (62 female and 13 male) were found in the 
dishes containing the dead bees. Of the 62 female mites, 8 were alive and active, 
while all the 13 males appeared dead. None of the females seen outside the bee 
were carrying fully developed ova. It would appear from these experiments that 
migration of both sexes takes place from the dead bee. 
3. An Endeavour to produce Infection artificially. 
(a) By contact with living sick bees. 
These experiments were carried out in small queen cages. The bees were fed 
with soft candy and kept as far as possible at the temperature of the hive. The 
infective bees were in five cases crawlers picked up from in front of the hive ; in two 
cases the bees were caught on entering the hive of a stock which was known to have 
a high per cent, of infection, and in the remaining three, the bees were taken from 
the frames of a sick stock. Virgin queens headed six of the experiments. 
In these experiments the healthy bees were maintained in contact with sick bees 
for periods extending from four to seventeen days. In only one case was a positive 
