ISO B.C. Entomological Societ.y. 



of nature by demolishing the abnormal conditions which we have created, 

 and by destroying only those species ivhich arc food-plants of the tent- 

 caterpillar we remove the cause of the outbreak and prevent its recurrence. 



For the past three years I have advocated this method of combating 

 the tent-caterpillar plague, and last year the City of Vancouver took steps 

 to carry this method into effect by having vacant lots cleared. But the 

 clearing has been overdone, and on that account may have to be repeated 

 in a year or two. Instead of destroying only food-plants, every tree and 

 shrub was cut to the ground, piled into heaps and burned, with the result 

 that a greater area is. available for the growth of food-plants than existed 

 before the ground was cleared, and much unnecessary expenditure was 

 incurred in cutting down trees which were not only harmless, but were 

 actually beneficial in hindering or limiting the establishment of food- 

 plants. 



Man's influence on the flora is therefore well illustrated in Van- 

 couver; instead of vacant lots covered with various evergreen trees, vine- 

 maple, cascara, dogwood, and other beautiful and harmless species, we have 

 waste ground for the reception of wind-borne seeds of alder, willow, fire- 

 weed, thistles, dandelions, and other weeds, and the prospect of a con- 

 tinuance of the tent-caterpillar pest until a new growth of immune trees 

 takes possession of such areas. 



It should be emphasized that all deciduous trees are not food-plants of 

 the tent-caterpillar, and those entrusted with clearing operations should be 

 able to distinguish the harmful species from the useful. This can be done 

 as easily in winter as in summer, and arrangements should be made to give 

 the men suflicient instruction in the identification of trees as would enable 

 the work to be done more effectively and more economically. 



Last summer on a small area comprising almost one-quarter of a block, 

 several men worked for the greater part of a week clearing off the vegeta- 

 tion ; it so happened that on this particular area there were comparatively 

 few food-plants of the tent-caterpillar, but there were many deciduous trees, 

 including maples and cascara-trees ; of the latter I counted ninety- four 

 specimens of average size, besides a number of saplings ; all were cut and 

 burned. One man could have cut all the food-plants in one afternoon ; 

 approximately $80 worth of cascara-bark would have been saved from the 

 flames, and the remaining cedars, Douglas firs, and maples would have 

 provided shelter, protection, and nesting-places for birds, many of which 

 assist in controlling insect pests. 



Trees which should be cut,. 



Amongst the local trees which are food-plants of the tent-caterpillar, 

 and which alone should be destroyed on vacant lots, are alder, various 

 species of willow, two species of poplar known as cottonwood and aspen, 

 wild cherry, crab-apple, and hawthorn; the latter, though not in evidence 

 in Vancouver, is very common in one or two municipalities in this region. 

 The following shrubs are also food-plants : Flowering currant, wild roses, 



