
858 THE AMERICAN NATURALIST. (VoL. XXXVI. 
species appeared, but numbers of old ones were found. On 
May 23, after a warm period with S., S.W., and S.E. winds 
of low velocity, fourteen new species were collected, a few old 
ones appearing. A N.E. wind on May 27, preceded by W. 
and N.W: winds of moderate velocity, brought in countless 
Colorado potato beetles and ten new species, the temperature 
dropping twenty degrees in two days. On May 31 a S.W., 
followed by a S.E., wind brought only two new species, but a 
good many old ones occurred. These results are placed on the 
preceding page in tabular form. 
DomINANT Forms. 
The first form to predominate notably was Chrysomela ele- 
gans (May 2), while. Hippodamia parenthesis came in a good 
second. The little Coccinella sanguinea occurred throughout 
the season in about the same numbers, but absence of other 
forms made it at times the dominant species. Black carabids 
occur also throughout, but never as dominant forms. The 
next visit, May 12, showed Diabrotica vittata as the charac- 
teristic species, while of Chrysomela only a few specimens 
were found. The small brown and black scavenger carabid 
was present in great numbers, and should probably be classed 
as the dominant form. Coccinella sanguinea was numerous, 
as were also black carabids. The following collection showed 
the Diabrotica, although not the characteristic species, still 
occurring in fair numbers; the scavenger carabid seemed to 
be the most numerous form, with quantities of Coccinella san- 
guinea. Of the larger forms Bombus sp.? and Hydrophilus 
triangularis were the most important. This time (May 16) 
marked the first occurrence of Galerita janus, and the flies 
were first noted. The various forms of Hemiptera occurred 
throughout the collecting trips, but were never dominant forms. 
On May 23 the Colorado potato beetle (Leptinotarsa decem- 
lineata) was the dominant form at Jackson Park. This appears 
to have been the vanguard of the great “migration” which 
took place on, or just before, May 27; for on that date the 
. beach at Cheltenham was- nearly covered with the beetles, 
