249 



SwAiNE (J. M). Injurious Shade Tree Insects of the Canadian Prairies, 



—Agric. Gaz. Canada, Ottawa, iii, no. 3, March 1915, pp. 215-220, 

 8 figs. 



The Manitoba maples, cottonwoods, poplars and willows, so widely- 

 used in the prairie provinces of Canada for shade and shelter belts, are 

 subject to attacks by very injurious insect enemies. Such outbreaks 

 were unusually severe during the summer of 1915. Poplars and 

 willows are frequently attacked by several leaf-eating beetles, including 

 Galerucella decora, Say (western willow leaf-beetle), Melasoma (Lina) 

 scripta (streaked cottonwood leaf-beetle), M. tremulae (unspotted aspen 

 leaf-beetle) and several allied species. Both adults and larvae of 

 G. decora feed upon the leaves, more or less completely destroying the 

 foliage and leaving the trees scorched and brown. The other species 

 have similar habits and frequently cause the same injury. M. scripta 

 and a closely allied species, M. interrupta, seriously injured wind- 

 breaks of willows in the summer of 1915 in Saskatchewan and Alberta. 

 Spraying w- ith lead arsenate or Paris green as soon as the beetles appear, 

 and again, if necessary, about ten days later, is an efficient control. 

 Ahophila pomeiarm, Harris (fall cankerworm) was particularly 

 injurious to Manitoba maples in Manitoba and' Saskatchewan in 1914 

 and 1915. The females, being wingless, crawl up the trunks to 

 deposit their eggs. The adult caterpillars descend and pupate in the 

 ground. The adult emerges in the autumn and the females oviposit 

 upon the bark of the branches and twigs. The eggs hatch late in 

 April, or in May, and the caterpillars feed upon the foliage for about a 

 month. Serious defoliation results if they are very numerous. The 

 moth of Palaeacrita vernata, Pack, (spring cankerworm) emerges from 

 the ground and deposits its eggs upon the bark in small clusters during 

 the first w^arm days of spring. Banding the trees to prevent the ascent 

 of the females or spraying with Paris green or lead arsenate as soom 

 as the caterpillars appear are the controls recommended. Chaitophorus- 

 negundinus, Thos. (Negundo Aphis) is the most persistent and serious; 

 enemy of Manitoba maples in the prairie provinces, inducing the 

 rapid development of a black sooty fungus, and sometimes causes 

 considerable defoliation. Usually the many insect enemies of this 

 pest so reduce its numbers that the trees may develop normally 

 through the latter half of the season. Kerosene emulsion, fish oil or 

 whale oil soap and the nicotine extracts are effective. Proteopteryx 

 willingana, Kearf. (Negundo twig-borer) is more or less injurious each 

 season to t^nlgs of the Manitoba maple. The caterpillar bores into 

 the young tw^gs, causing them to develop into elongated hollow galls 

 within which the caterpillar lives and feeds, extruding the excrement 

 through a hole in the side. The caterpillars reach full growth in June 

 and pupate either in the ground beneath the trees or, less frequently, 

 within the galled twigs. The only control which has been suggested 

 is to collect and burn infested twigs, but it is possible that a spray of 

 Paris green or lead arsenate applied about the end of June would 

 destroy many of the young caterpillars. Saperda calcarata (poplar 

 borer) is a common and destructive enemy of all kinds of poplars. 

 Rough, blackened scars and swollen areas on the trunk and branches, 

 with large tunnels piercing the wood beneath, are evidences of its work. 

 The eggs are laid in the bark of poplars during the latter part of the 

 summer. The whitish grubs feed first in the inner bark and then bore 



(C275) WtPl/106. 1,500. 7.16. B.&F.Ltd. G.11/8. A 



