66 



The Canadian Field-Naturalist 



IVOL. XXXVI 



Lake Trout. CristU^omer namaycush. Two 

 fine specimens nearly 3 feet in length caught by 

 our party at Wrigley Harbour, June 12th. 



Arctic Grayling. Thymallus singifer. Two 

 caught at Wrigley Harbour, June 12th. Common 



in Smith Creek, 12 miles above Fort Wrigley. 

 Pike or Jackfish. Esox lucius. Very common 

 and up to 3 feet in length at Wrigley Harbour, 

 June 12th. 



MANITOBA GRASSHOPPERS 



By Norman Criddle 



(Continued from Vol. XXXVI, No. 3, March, 1922.) 



GRASSHOPPERS, as a whole, form an ex- 

 tremely important class of insects. As 

 farm pests they are probably second to none, 

 while indirectly they are an asset which assists 

 greatly in the perpetuation of wild life. To the 

 farmer, they are frequently very obnoxious, to 

 the sportsman beneficial, to the community at 

 large occupying a position that cannot be definite- 

 ly classified at the present time. It may be 

 useful or harmful, but much more will have to be 

 known about the economic relation between 

 grasshoppers and other animals before accurate 

 information is available on this last point. No 

 one can say truly that the world would be better 

 without grasshoppers, yet the losses they cause 

 each year aggregate millions of dollars. 



Nearly all grasshoppers are vegetable feeders, 

 but it does not follow that they are necessarily in- 

 jurious on that account. Most of them might 

 become so were they to increase sufficiently, but 

 the majority of them never do, and we can, there- 

 fore, restrict the truly destructive species to a 

 comparatively small proportion of the total 

 number existing. 



In spite of the devastating habits of certain 

 species, grasshoppers, as a whole, play an import- 

 ant part in the scheme of nature; but for them a 

 number of creatures could not exist at all, while 

 many others would be much reduced in numbers. 

 In the insect world there are certain Diptera, 

 Hymenoptera and Coleoptera that live entirely 

 at the grasshopper's expense. These are of a 

 parasitical or predaceous nature. Some of this 

 cla.ss devour the eggs, others live within the adult 

 bodies. The egg destroyers are extremely import- 

 ant in reducing locust outbreaks and during the 

 last three years they have done more than any 

 other grasshopper predator to bring the outbreak 

 within bounds. A certain Bee-fly (Systaechus 

 vulgaruf) has been of much value in this respect. 

 The adult is a very hairy yellow fly generally 

 found resting upon flowers, the larva, a much 

 wrinkled inactive grub, met with among the 



grasshopper's eggs. Of the Coleoptera, Blister 

 Beetles play an important part in destroying 

 grasshopper eggs. There are various species of 

 this beetle which in the adult stage devour vege- 

 table matter. One (Macrobasis murina) is an 

 important pest of potatoes in Western Canada, 

 and here again there is difference of opinion as to 

 whether a species does more harm than good. It 

 cannot, however, exist without grasshopper eggs 

 and for that reason it only becomes a pest during 

 serious grasshopper outbreaks. Another beetle 

 larva (Percosia obesa) runs actively about the 

 surface of the ground in search of food and is an 

 expert at locating locust eggs. Having discovered 

 a sac of these it proceeds to make itself at home 

 until it has eaten them. We found a number of 

 these larvae with eggs in their jaws during 1921 

 and so intent were they upon the feast that they 

 continued to enjoy it even when placed in confine- 

 ment. 



Certain Flesh flies (Sarcophagidae) are also 

 valuable grasshopper exterminators. These flies 

 usually attack the adult grasshopper and deposit 

 their maggots while their host is on the wing. 

 Of the wasp-like flies (Hymenoptera) a number 

 could be mentioned as grasshopper hunters. 

 Some of these make individual grasshopper eggs 

 their home in which they develop through all 

 their stages. Others carry off their victims bodily 

 and store them in burrows as food for their young. 

 These insect enemies are extremely useful in 

 man's welfare and without their aid grasshoppers 

 would increase beyond all bounds. 



Perhaps the greatest benefiters from grass- 

 hoppers are birds and I believe it would be easier 

 to enumerate the species that do not eat these 

 insects than to list the ones that do. 



In the Middle West, Grouse, such as the Sharp- 

 tail, multiply or decrease in accordance with the 

 number of grasshoppers present, because the 

 rearing of young depends largely upon the avail- 

 able supply of hoppers. The Western Meadow 

 Lark is another bird whose numbers are maintain- 



