1921 ENTOMOLOGICAL SOCIETY. 31 



Paris green was rapidly used up, some lead arsenate, and Black-leaf-40 were un- 

 earthed from forgotten stocks, but by July 30th a newspaper headline announced 

 thaj; there was " No Poison in City to Destroy Bad Bugs." As a result many 

 methods, some of them rather unfortunate, were advocated and put into practice 

 by the city authorities. Among these was the use of a flame thrower for the treat- 

 ment of vacant lots, on. which lambs-quarters grew to profusion. 



Migrations of larvse, however, precede by a few days only their entrance 

 into the soil for pupation and the trouble subsided almost as quickly as it arose. 



At the laboratory it was anticipated that the second generation would greatly 

 outnumber the first. Such had been the case in former years. This belief was 

 strengthened when the second flight of moths appeared. As was stated earlier, 

 we captured some 2,000 moths a night in June, during the first flight. Early in 

 August, however, our trap repeatedly overflowed, and since it had a capacity for 

 only some 15,000 moths we do not know how many more visited that single electric 

 bulb in a night, and escaped, by being unable to fall into the cyanide jar below. 

 For this reason we considered it advisable once more to enlist the services of the 

 press in order that we might warn the public of what they might anticipate. 



The second generation, however, failed to materialize, owing to the following 

 interesting conditions. 



During July the whole infested territory was blessed with two days of heavy 

 rain. This was followed by hot " forcing " weather. As a result there was an 

 excessive growth of tender lambs-quarters, on which the moths laid their eggs 

 in abundance, Subsequently there was an entire absence of rain until late in 

 the fall. This dry period was accompanied by hot winds which soon dried up the 

 egg-infested weeds. In many cases the eggs had not hatched, while very few of 

 the larva? were sufficiently mature to migrate when the food supply was thus cut off. 

 Hence the majority of them died from starvation among the dead weeds on which 

 they had bred. The shortage of food resulted in an. acceleration of maturation in 

 the case of a few individuals, with the result that, during the middle of September, 

 our trap captured a few dwarfed adults, which had little more than half the wing 

 expanse of the normal moth. This is our only record of a partial third generation 

 in Alberta. 



Some idea of the possibilities of the second generation, given favourable 

 conditions, was gained in the irrigated district around Brooks. Here the weeds 

 remained succulent, thus allowing the larvae to develop and to migrate normally. 

 In this district the first generation was insufficiently numerous to attract attention. 



Towards the end of August several fields of first year alfalfa, standing about 

 one foot in height, were attacked by migrating swarms. Almost overnight, they 

 had every leaf veined, so that the whole field turned white. The growers feared 

 that their crops had been killed outright. Alfalfa, however, stands more rough 

 treatment than does any other crop grown in Alberta, and when the infested 

 fields were inspected on September 10th they were found to be covered with new 

 growth and apparently they suffered very little from the close pasturing to which 

 they had been subjected. 



Probably the Beet Webworm will attract little attention in 1921, even though 

 cocoons containing hibernating larva? are abundant in weedy stubble field. When 

 it is present in comparatively small numbers it is always a beneficial insect, and 

 despite the alarm and inconvenience that it caused this year we are convinced 

 that its activities have been of financial benefit to Southern Alberta. 



