April, '11] criddle: Manitoba insects of i9io 239 



many crops. The successful application of this mixture is largely due 

 to weather conditions. Firstly, the day chosen for spreading it 

 should be sunny with the temperature above 60° F. in the shade. 

 Secondly, dry conditions will always prove advantageous and bring 

 greater results than wet, as then the mixture will be attractive on 

 -account of the moisture it contains, apart from any other attraction. 

 Indeed, on hot, dry days locusts will often travel some distance towards 

 a receptacle containing water. Thirdly, it is advantageous to spread 

 poison during the warmest part of the day, as it is then that grass- 

 hoppers are most easily enticed towards it. 



An examination reveals many egg masses present on stubble and 

 other suitable land, so that under ordinary conditions another out- 

 break of greater severity may be expected in 1911. 



Several parasites were present. Firstly, a Tachina fly caused many 

 deaths during July and then three species of blister beetles were present 

 in unusual numbers, namely Contharis nuttalli, Epicauta pennsyl- 

 vanica and E. sericea. The first two subsist largely upon members 

 of the pea family though the second did some injury to potatoes 

 and beans. The last appears to confine itself to lamb's quarters. 



An extensive migration commenced among locusts late in July 

 and continued, when the weather permitted, until the 16th of August. 

 The days chosen were hot and sunny with a moderate breeze. Looking 

 up towards the sun with sufficient shelter to hide its disc, revealed 

 a continual swarm passing by with the wind from a few feet above 

 the ground to as high " as sight could detect the glistening wings 

 when passing near the sun. 



Injury was also caused by eating through twine used to bind sheaves, 

 in some places fully 70 per cent being cut through. Soaking balls of 

 twine in two pounds of copper sulphate to ten gallons of water proved 

 a perfect preventive, though it has a tendency to rot the twine and 

 cause trouble when binding. If dried very quickly, however, this is 

 partly avoided. 



Locusts responsible for most of the injury done were, Melanoplus 

 atlanis, packardii, angustipennis, bivittatus, extremus and dawsoni, 

 in the order named. 



Insects Injurious to Roots and Vegetables 



Imported Cabbage Worm, Pontia rapce. — Much less injurious than 

 last year and did comparatively little injury. 



Colorado Potato Beetle, Leptinotarsa decimlineata. — We experienced 

 the worst outbreak on record of this insect. No potato patch was free 

 from it anywhere. 



