THE ACRIDIIDAE OF MINNESOTA 
on 
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upon dark soils, the darker forms, approaching the coloration of the 
soils, predominate. Hancock (Nature Sketches in Temperate Amer- 
ica, pp. 346, 347) has described a series of experiments made to deter- 
mine the effect of environment, and more especially of soil back- 
ground, upon these insects. His conclusions may be quoted here. “In 
these experiments, together with others that I have made, the evidence 
indicates that the Carolina locust does not change abruptly at the 
critical period during the last ecdysis, or moult, from one color to an- 
other but a change takes place in the adult gradually after the last 
moult. Whether this 1s in sympathy with the surroundings is not 
definitely proven. But the indication is that the hypodermal cells lvine 
Fig. 7. Normal Habitat of Dissosteira carolina C. W. Howard 
in the integument of the newly moulted adult are very sensitive to 
light and humidity and are capable, under the effects of these stimult, 
of responding by changing color in accordance with that of the habitat.” 
When in flight the broad expanse of wing and the contrasting colors 
of the largely black surface and the light outer margin make it a very 
conspicuous object, but immediately upon alighting the insect nor- 
mally blends so perfectly into the color scheme of the background as to 
be almost indistinguishable. 
The males of this species frequently exhibit a very interesting per- 
formance in midsummer. They will rise into the air a few feet and 
poise there, the wings being vibrated rapidly with a whirring sound 
