30 THE REPORT OF THE No. 36 



before they succumbed. Furrows treated with poisoned bait proved to be effective 

 in staying the approach of armies, but since the larvas bred for the most part upon 

 weeds in "stubbed in" grain fields, and the gardens were often adjoining such 

 fields, little was seen of the moving swarms till they had actually entered the 

 gardens and had almost destroyed them. 



On the 23rd-25th of July a trip was made from the laboratory through the 

 worst infested area. For mile after mile the roadsides were stripped bare of weeds, 

 while from many grain fields which had been shockingly weedy there now projected 

 above the wheat, only a forest of bare lanabs-quarters' stems. The wheat being 

 practically immune from attack now had the fields to itself. To what extent this 

 most effective weeder improved our crops, which were unavoidably weedy owing 

 to the exceptional seasonal conditions, it is difficult to estimate. One farmer, who 

 was receiving much commiseration from his neighbours since his wreck of a 

 garden had always been considered the best for miles around, was with difficulty 

 lured from the Paris green and coal oil that had taken the entire attention of his 

 family and himself since the larvas appeared. He did not want to take us to his 

 fields, for he said that he was ashalmed of them ; he knew they contained more weeds 

 than wheat. When, however, we had made a thorough inspection of them and had 

 found them entirely free from weeds, he asserted that after all the " worms " were 

 the best thing that had ever come his way. The depredation to gardens, however, 

 attracted far more attention than did the improvement of grain fields. At every 

 point visited the same conditions were encountered. Onions were invariably wiped 

 out of existence, and the " worms " often followed these plants down below the 

 surface of the soil in order to feed on the bulb. Sunflowers which are now some- 

 what extensively grown, had their leaves veined overnight, cabbages, turnips, swedes, 

 and rhubarb came next in preference, beans were less favoured than peas, while- 

 potatoes enjoyed immunity when other dainties were present, but fields of this 

 crop which were free from weeds suffered as badly as any, for the larvse had a 

 tendency to bite through the stem, thus cutting off, though not eating the leaves. 

 The most surprising observation regarding the food choice of these Beet Webworms 

 was that they never fed on beets till they had exhausted other possibilities. Cot- 

 tonwoods and other poplars to a height of three to four feet from the ground, had 

 their leaves stripped of epidermis. This was a new record, for in former years 

 these trees had proved immune. 



In so far as field crops were concerned grain was almost untouched. Wheat, 

 in some cases, had a little epidermis removed from a few blades after all weeds 

 had been entirely destroyed, but the damage was insignificant. No feeding 

 was observed on oats or barley, though we received an unconfirmed report that 

 rye had suffered rather severely. In a few cases corn leaves were attacked and had 

 the upper epidermis extensively eaten. Flax, though fed on freely, was left 

 untouched until all lambs-quarters, pigweed, Russian thistle and buck brush had 

 been consumed. Alfalfa, however, was eaten readily. Fortunately the first 

 generations of webworms were not presen-t in large numbers in the alfalfa-growing 

 districts of Alberta. 



On July 26th migrating swarms of larvse appeared in the city of Calgary, 

 and their numbers increased with such startling rapidity that the effect upon the 

 citizens might almost be described as one of panic. Newspaper headlines referring 

 to the " devastating bugs " appeared in type that is usually reserved for announcing 

 war news or murders. Not only were gardens destroyed wholesale, but the larva? 

 were entering houses, much to the annoyance of their inmates. All available 



