304 THE CANADIAN ENTOMOLOGIST. 



and were all traced by their stridulation. When discovered, they were 

 sometimes foimd perching in a conspicuous position upon the upper side 

 of a leaf or twig of some shrub, a few feet from the ground, but several 

 times the sound was traced to the trunk of a tree, and the musician was in 

 some cases too high up to be detected. One was seen on the trunk of a 

 black spruce, about twelve feet from the ground, and could just be reached 

 with the net by standing upon a nearby stump. 



The stridulation of this grasshopper is a soft trill of little volume, 

 audible at a distance of but a few yards. It is sometimes continuous for 

 some seconds, but is generally interrupted rhythmically, the divisions 

 being produced at a rate varying according to the amount of sunshine. 

 In bright sunshine I counted forty in fifteen seconds, the rate being thus 

 2^ divisions per second, but on an afternoon when the sun was almost 

 wholly overcast the rate was reduced to forty-one or forty-two in thirty 

 seconds, or about half the rate in sunshine. When close to the stridulat- 

 ing insect I could detect that there were no absolute pauses between the 

 trills, a very low trilling sound filling in all the intervals. The rhythm is 

 not always quite regular. Sometimes after a succession of trills of appar- 

 ently equal length one may be shortened or lengthened, and then the 

 regular trilling resumed. 



All the specimens of this insect seen were of the brachypterous form, 

 with one exception, in which the tegmina and wings were similar to those 

 of the macropterous individual figured on plate 7, Can. Ent., Ioc. cit. 



The stridulation of Chloealtis abdomifialis Thomas was also heard 

 repeatedly at this locality, and can be fairly well represented by 

 "zip-zip-zip . . . . " repeated continuously at a rate varying from 

 five per second (late afternoon sun, nearly overcast), to a Utile over six 

 per second (bright sunshine). Doubtless the rates in both these cases 

 vary more than these observations show, it being a general rule among 

 the Orthoptera that a lowering of temperature produces a corresponding 

 retardation in the rate of stridulation. 



Only one species of Orthoptera was taken in the vicinity of Fort 

 William that was not observed here in 1908. This was Nemobius 

 fasciatus abortivus Caudell. The specimens were confined to a small 

 sandy area thinly clothed with grass and weeds. They were very small, 

 and the stridulation was a low continuous trill, differing thus from that of 

 typical /^j-r/rt/?^^. It is thus possible that this form is specifically distinct. 



