B.C. Entomological Society. 



short paper. In common with many of our native insects, this pest is subject 

 to years of abundance followed by several years of scarcity, and this is but 

 one of the many outbreaks recorded in the history of our continent. The 

 caterpillars are voracious feeders, and during the years of abundance much 

 damage is done, in addition to the unsightly appearance and inconvenience 

 caused by their presence. The history of the forest tent-caterpillar as 

 recorded in our available literature is given briefly on the accompanying 

 chart. A more detailed account may be found in the Annual Report of the 

 Entomological Society of Ontario, 1916. 



It will be noted that outbreaks have occurred at intervals of eight to 

 ten years and the average duration was about three years. 



Life-history and Habits. — The insect spends the winter as a tiny cater- 

 pillar in the egg-shell. The eggs are deposited in masses of from 250 to 

 400 in the form of rings or masses on the terminal twigs and smaller 

 branches of the trees. The masses are covered with a shellac-like material 

 which serves to hold the eggs together and protect them from the weather 

 as well. 



The caterpillars emerge from the eggs in the early spring and feed upon 

 the opening leaves. Those from each mass, or from several masses in the 

 case of an outbreak, usually keep together and feed in congress until nearly 

 full-grown. As the caterpillars grow they moult, or cast off their outer 

 skins several times, and the dry skins are often found in large numbers on 

 the tree-trunks and taken by many to be dead caterpillars. 



When the caterpillars become full-grown, which usually requires about 

 eight weeks, they spin their cocoons and enter their chrysalid or pupal stage. 

 The cocoons may be found fastened to the leaves of trees, in crevices of the 

 bark, under fence-rails, under the eaves of houses, and in many other places. 



The moths emerge in from two to three weeks. They are medium-sized 

 moths and are reddish-brown in colour, with two more or less distinct band^ 

 across each front wing near the middle. They fly at night, and after mating 

 the males die within a day or two and the females deposit their eggs as soon 

 as they have found a suitable location. The females will not deposit their 

 eggs until they have been fertilized and may live for two or three weeks. 

 There is only one generation a year, the eggs deposited in July remaining 

 on the trees until the following spring. 



Control. — The control of these insects in forest lands is not at present 

 economically possible, but the following control methods are applicable to 

 orchards, city lots, shade-trees, and parks : — 



(i.) Destruction of Egg-masses. — During the winter months the egg- 

 masses are easily seen on the twigs, especially on the smaller trees, and much 

 good can be done by removing and burning them before hatching-time, and 

 although some masses will be missed the caterpillars from these will be more 

 easily controlled. 



(2.) Destruction of Clusters of Caterpillars. — The forest tent-cater- 

 pillars may be removed when they are in clusters on the trunk or lower 

 branches on the tree, either by scraping them off with a hoe or stiff wire 



