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182 P. Harris
Recommendations
Acknowledgements
Literature Cited
where there are extensive dense stands of toad flax. Based on the results from Ontario,
it is doubtful whether the establishment of C. lunula in the area would solve the
problem. Whether it is worth screening and establishing a fourth agent for the control
of toadflax around North Battleford needs to be determined by a cost-benefit study as
opinions vary about the importance of toadflax to the region.
Surveys for the biological control agents of toadflax and their host specificity testing
should not be done by Canada unless it can be shown that the potential benefits are
large enough to justify the costs of biological control. However, the costs to Canada
for biological control would be minimal if the tests were done by other countries. In
this event the control agent should be imported as there would be benefits to individual
land holders from the biological control of Dalmation and common toadflax. The moth
C. lunula can almost certainly be established outside Ontario.
I am grateful to Mr Ian Jones for the observations on C. lunula in the Ottawa area in
1980 and 1981.
Darwent, A.L.; Labay, W.; Yarish, W.; Harris, P. (1975) Distribution and importance in northwestern Alberta of loadflax and its insect
enemies. Catuldian Journal 01 Piant Science 55, 157-162.
Harris, P.; Carder. A.C. (1971) Linaria vulgaris Mill .• yellow loadfiax and L. dalmaJica (L.) Mill .• broad-leaved toadflax (Scrophulariaccae). In:
Biological control programmes against insects and weeds in Canada 1959-1968. Commonwealth
inslilute 01 Biological Control Technical Communication 4. 94-97.