n found
converting the inner parts of the husk into a blackened, pulpy mass.
Infested nuts are disagreeable to handle and the husk does not part
readily from the shell. I have found the fly attacking black walnuts,
butternuts, Persian walnuts and Japanese walnuts, within the states of
West Virginia, Maryland, Pennsylvania, Ohio, New York, Connecticut and
Massachusetts. It probably occurs over the natural range of the black
walnut and butternut. It is proving to be a rather serious pest,
especially of the Persian walnut. Some of the infested walnuts appear to
drop prematurely and others adhere to the branches beyond the regular
harvest time. The shell of infested Persian walnuts parts poorly from
the husk and the nut is discolored, soiled and unmarketable.

The fly has rather interesting habits. I found that by pricking a nearly
mature black walnut with a pin, the wounds would almost invariably be
used in a little while by the female flies for depositing their eggs. In
one such wound, 180 eggs were laid within 24 hours. When the husk was
pricked a slight flow of juice would take place and the male flies would
soon find the spot, and, recognizing, I suppose, a suitable place for
the females to come to oviposit, they would stand guard at the puncture
awaiting the coming of the female. On one occasion I made minute
punctures in the husk of eight black walnuts and in a little while a
male fly was located at each puncture. Pairing took place usually as
soon as the female came and began to lay eggs. Sometimes a male would be
found at a puncture in the early morning and would hold its position
against all coming males throughout the entire day. When another male
would come to the nut the two flies would rear up facing each other and
engage in a brief sparring bout with their front legs. Usually, the
original occupant of the nut would be the victor. In some experimental
spraying of Persian walnut trees in Maryland and Pennsylvania the past
season with a sweetened arsenate of lead spray apparently good results
were obtained. In one case it seemed that the spraying was about 75 per
cent efficient in controlling the pest. In in another case, whereas last
year 75 nuts in 100 were infested, this year, after spraying only four
nuts in 100 contained the maggots at harvest time.

I desire to state to the nut growers that I am interested in any nut
insect problems that you may encounter and shall always be glad to
receive reports and sp