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Table 48
Releases and Recoveries
Evaluation of Control Attempts
Linaria \·ulgaris Miller. 181
The area has not been surveyed since 1972, but the moth has continued to spread; it
was recovered from light traps at Ottawa, Ontario in 1977, a distance of over 300 km
from the release site (E. Monroe, 1978, personal communication). Thus C. lunula is now
probably present in most of southern Ontario. According to I. Jones (1978, personal
communication), larvae were scarce in the Ottawa area in 1980: less than half a dozen
were seen in several organized and many casual searches. In 1981, there was a large
increase in the population, larvae were seen from early June to mid-October and along
the railway track 47 to 57 larvae could be collected in an hour. Defoliated stems were
evident, and some small stands were completely defoliated. Both the larvae and defoliation
were associated with stunted toadflax plants and they rarely occurred in adjacent
lush stands.
Op'en releases and recoveries of Calophasia [wUlla against L. vulgari.v Mill. and L.
dalmatica (L.) Mill.
Year of
Weed Species Province Year Origin Number Recovery
L. vulgaris New Brunswick 1971 Ontario 1565 larvae
& 136 pupae
L. vulgaris Saskatchewan 1973 Ontario 2725 larvae
L. dalmatica British Columbia 1969 Ontario 200 pupae
L. dalmatica British Columbia 1971 Ontario 1180 larvae
Four attempts were made to establish Calophasia lunula in regions of Canada outside
Ontario and all were unsuccessful (Table 48). The release site in Saskatchewan was
flooded in the year following the release. The larvae released on Dalmation toadflax in
British Columbia disappeared within days, apparently from ant predation. Survival
was not followed closely in New Brunswick but no evidence of establishment was
found in the following year.
The moth, C. lunula, is obviously well established in Ontario and it should be possible
to establish it in the rest of Canada. C. lunula has not defoliated enough L. vulgaris to
control the weed on its own, but it has added to the stress inflicted by the now
ubiquitous beetles, G. antirrhinii and B. pulicarius. The possibility that it may
sometimes inflict more damage is indicated by the populations in Ottawa in 1981 which
seem to be about ten times the density at Belleville prior to 1972.
C. lunula favors the stunted toadflax stands that are found on dry soils. It is these
stands that are persistent as edaphic conditions that permit the formation of tall lush
stands also lead to the displacement of toadflax by grass and other vegetation. Thus C.
lunula concentrates its attack where the weed is most persistent.
The combination of the three toadflax insects can control L. vulgaris at below the
economic threshold in most parts of Canada. Indeed in most regions this has been
achieved by the two beetles alone. An exception is North Battleford, Saskatchewan,