Glendale, Mass.
1911.
Sept 1
[September 1, 1911]

  Sunny, warm & rather sultry with light southerly breeze.

Southward migration of Milkweed Butterflies

  On August 30 I saw three Milkweed Butterflies flying southward
high in the air. To day they were unmistakeably migrating in the same
direction and in considerable numbers but invariably singly & so widely
separated that I did not ever have two in sight at once. Some passed
just over the tops of the taller trees, others at a height of fully 100 yards,
the latter looking exceedingly like birds. All went straight down the valley
towards the [?] until lost to sight in the distance. Just after
sunset I noticed that those which continued coming from the north
stopped at the line of tall ash trees bordering on the road and went to
roost then on the under side of leaves near the tops of those trees.
I saw a dozen or more arrive and settle there in the course
of as many minutes. One that I noticed earlier in the day rose
from a clover field to an elevation of about 200 feet & then
started southward mounting upward in a spiral course precisely as
a bird might have done. The flight continued all through the day.