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Vol. LII. LONDON, JUNE and JULY, 1920. No. 6 



POPULAR AND PRACTICAL ENTOMOLOGY. 

 Fragments ix the Life-Habits of Manitoba Lnsects — IL 



BY NORMAN CRIDDLE, 

 Dominion Entomological Laboratory, Treesbank, Man. 



In a Province such as Manitoba, which is comparatively new agriculturally, 

 we are continually experiencing insect outbreaks involving species not hitherto 

 known to be obnoxious. The insects concerned are always native to the country 

 and frequently owe their increase to the development of agriculture, which 

 has been the means of placing new food supplies at their disposal. In other 

 instances the insects have doubtless multiplied abnormally in the past but 

 owing to the lack of observers at such times, their abundance apparently did not 

 attract attention. Two such outbreaks have occurred in Manitoba within the 

 last few years and though my notes relating to them are by no means complete 

 they seem, however, sufficient to indicate the general habits of the insects con- 

 cerned, and have, therefore, been brought together for publication under the 

 above heading^. 



The Brome-grass Cutworm. 



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{Trachea faniti ma cerivana Smith). 

 The larvee of this insect are unobstrusive in their general habits and might 

 pass unnoticed were it not for the fact that they gather in the sheaves of Brome- 

 grass (B. enermis) to hide. The caterpillars are naturally shaken out of these 

 sheaves at harvest time and in consequence attract attention as they crawl 

 about the bottoms of the racks when the grass is being threshed. 



The Brome-grass Cutworm is a surface feeder which hides under, or in, 

 any convenient object, such as hay, etc., during the day and comes out to feed 

 at night. It attacks the, young shoots, or tender leaves, of various succulent 

 grasses but shows a marked preference for brome-grass. The larva? first attract 

 attention about the middle of September when they gather into the grass sheaves 

 which have been cut for seed purposes. Apparently the insects enter the sheaves 

 with the object of securing shelter rather than for hibernating purposes, as they 

 still continue to feed at night, though not very extensively. By the middle of 

 October the caterpillars have attained a similar size and have finished feeding 

 for the year. At this date,, most of them leave the sheaves that are standing 

 upright but they may still be found beneath those lying down or under any other 

 conveniently placed object. They are now often partly buried in the soil show- 

 ing that the time of hibernation has arrived. 



In the spring, larvae still remain in the vicinity of their hiding places and 

 appear to eat comparatively little. They are, however, active by the time 

 farming operations commence and continue to feed until they pupate in early 

 May. A description of the caterpillars as they are met with in autumn follows : 



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