Variegated Cutworm Economic Loss
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Variegated
Cutworm: Leaf Consumption and Economic Loss in Peppermint
Ralph E. Berry and Elson J. Shields
Department of Entomology, Oregon State University,
Corvallis, Oregon 97331
© 1980 Entomological Society of America
J. Econ. Entomol. 73: 607-608
ABSTRACT
Mean total consumption of peppermint foliage for Peridroma saucia (Hubner)
instars 3-6 was 2.3+1.2, 7.2+2.5, 31.5+5.0, and 133.6+25.4
cm2, respectively. Total consumption of 174.4 cm2 was equivalent to 26.7 peppermint
leaves. Instars 5-6 consumed 94.5% of the total foliage consumed during development of
instars 3-5 (25.3 leaves). Mean number of days for development of instars 3-6 was 3.2+0.4,
3.9+0.4, 4.8+0.9, and 10.0+2.0, respectively. Peppermint plant
samples (1000 cm2 soil surface area) were used to estimate mean leaf size (6.5+1.4
cm2), total leaf area/1000 cm2 (6247+1105 cm2, and mean oil yield/1000 cm2 (0.8+0.1
ml).
It was estimated that 0.9 5th and 6th instars/1000 cm2 would cause a 2.4%
defoliation which was equivalent to the economic injury level for variegated cutworm on
peppermint based on an oil value of $22/kg and a total cost of insecticide treatment of
$45/ha.