J. Rennie and C. H. Sutherland 205 
case of the second generation which began to appear on July 25th, the period 
during which emergence took place was about three weeks. 
In order to find out from what depths the adult fly could emerge, the 
following experiments were set up. 
Glass cylinders were filled with earth; in one the soil was loose, in another 
the soil was moderately compact. Puparia were placed at various depths, 
these being indicated by strips of gummed paper at the same level on the 
glass cylinder. 
It was found that in loose soil the adult fly emerged from puparia placed 
at a depth of 2 and 3 inches, but did not emerge from puparia placed 6 inches 
below the surface. In moderately compact soil, the adult fly emerged from 
puparia placed at a depth of 3 inches, but not from a depth of 6 inches. The 
puparium cases were afterwards found at the levels at which they were 
originally placed. It has been noted that the parasitic maggot, after leaving 
the dead host, is capable of moving about in the soil, and probably it moves 
upward near the surface before pupating. 
Mating. 
Mating took place freely in the cage; in 1918 from May 16th to the end 
of the month; in 1919, from June 2nd till about the 12th. 
Mating Bucentes were isolated in a test-tube with one or two daisy blossoms 
and kept under observation. The flies were found to remain in coitu over a 
period of about two hours. Oviposition was not observed, but flies which had 
mated were found to survive 4-5 days. 
During both seasons, 1918 and 1919, pairs of mating flies were isolated 
along with Tipula larvae, and also in view of their recorded occurrence in 
Mamestra, along with various caterpillars, e.g. Agrotis exdamationis. No 
infection took place under these conditions. 
Longevity of the Imago. 
Experiments were carried out to ascertain longevity of adult Bucentes , 
wherein newly-emerged flies were isolated in glass cylinders. In the bottom 
of the cylinder was put about 2 inches of earth in which one or two flowering 
daisy plants were placed to provide food for the flies. Under these conditions 
the flies survived 5 to 10 days. Under natural conditions they doubtless live 
longer than 10 days. 
The confined flies are strongly attracted to light, they are exceedinglv 
active and run about freely upon the surface of the soil. This was planted 
with daisies and dandelions, which were much sought, the flies being seen to 
introduce their proboscides into the daisy florets and to feed on the pollen. 
Summary of Life History. 
So far as we have been able to trace the life history of Bucentes geniculata 
it may be summarised as follows: 
