Authors: Jason Wurster and Laura Timms, Faculty of Forestry, University of Toronto
Variegated cutworms, Peridroma saucia, have four stages of development: adults, eggs, larvae, and pupae. Larvae characteristically have 4 to 7 pale yellow circular spots on their backs. Although variable, the backside colour is usually brown while the underside of the caterpillar is cream coloured and the sides have a narrow, orange-brown stripe. Mature larva will grow up to 50mm long and 6 to 7mm in diameter. Adult variegated cutworms are inconspicuous moths. Forewings are yellow or brown with pale mottled designs and the hind wings are white with brown veins and margins. Moths have a wingspan varying from 3.8 to 5.0cm.
Variegated cutworms are distributed worldwide and can be found throughout North America (Canada to Argentina). Along with North America, variegated cutworms are widely distributed in Europe, Asia Minor, North Africa, the Middle East and mid-oceanic islands such as Bermuda and Iceland in the Northern Atlantic, and Tristan da Cunha and Gough Island in the Southern Atlantic. On the Pacific side, variegated cutworms can be found in both Hawaii and the Galapagos Islands. Variegated cutworms are considered true or obligatory migrants because they travel south much like certain bird species to avoid the colder winter months in the north. They are able to travel considerable distances at night because they are exceptional flyers, being able to fly for several hours at speeds between 2-6 km/hr when the air is still. With wind assistance their flight speed can be even faster.
All species of cutworms are general feeders, affecting a wide range of plants. Variegated cutworms consume a wide variety of fruits as well as vegetable and field crops. Fruits commonly damaged are apples and tomatoes. Vegetable crops include asparagus, bean, cabbage, and other crucifers, celery, carrot, corn, lettuce, pea, pepper, and potato to name a few. In addition to crops their diet also consists of plants such as aster, carnation, chrysanthemum, dahlia, gladiolus, marigold, nasturtium, pansy, rose, violet, and zinnia.
Damage from variegated cutworm begins in the early spring and continues throughout the summer. Larvae are inactive during the day and can be found in loose dirt or under debris such as leaves on the soil surface. Night is when the cutworm larvae come out to damage plants. Variegated cutworms will cause damage to nearly all fruits, vegetables and ornamental plants. Hosta and Petunia are two common plants that are affected by cutworms due to their fleshy leaves and low growing stems. When affected by cutworms, the leaves of a Hosta plant will have large irregular holes at the edges or rectangular holes within the leaf enclosed by veins. Damage by variegated cutworms are more common in areas of high density planting where limbs bearing either fruit or vegetables touch the ground.
The length of the life cycle of variegated cutworms varies with temperature. When temperatures are between 15 and 32 degrees Celsius development time can range from 35 to 62 days, allowing for 4 to 5 continuous generations per year. In temperate regions moths emerge from overwintering pupae in early spring. Eggs are laid by adult females in clusters of 40 to 70 on the stems of dead twigs, plant stems, and leaves. Eggs hatch within four to nine days, depending on temperature. Larvae will feed and grow from 33 to 40 days until fully grown. Once matured, larvae enter the soil, form a cell and pupate.
Control and Management
The Variegated Cutworm has many natural enemies. Euplectrus plathypenae Howard is a parasite known to attack the cutworm. Other suspected parasites are Archytas cirphis Curran, Chaetogaedia monticola (Bigota), Chelonus texanus Cresson, Eucelatoria armigera (Coquillet), Hyposoter exiguae (Viereck), Meteorus laphygmae Viereck, Pseudamblyteles koebelei (Swezey), and Pterocormus rufiventris (Brulle).
Chemical control can be easily accomplished with the cutworm by applying granular insecticides, such as pyrethroid insecticides onto the soil surface. Whenever choosing a pesticide to control a pest, consult your local extension office or department of agriculture for the most up to date and accurate recommendations for your area.
The best natural way to prevent variegated cutworm from affecting plants and trees is to keep limbs, vines, or shoots trimmed and away from the ground as cutworms tend to climb from the ground up.
- ↑ North Dakota State University, Department of Entomology. N.d. Variegated cutworm (Peridroma saucia). Available online: http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/Lawn_Ornmntl/variegated_ctwrm.htm 1.0 1.1 1.2
- ↑ Mau, R.F.L, Kessing, J.L.M. 2007. Peridroma saucia (Hubner), Crop Knowledge Master. Honolulu, Hawaii Department of Entomology. Updated April 2007. Available online: http://www.extento.hawaii.edu/kbase/crop/Type/peridrom.htm 2.0 2.1 2.2 2.3
- Pogue, M.G. 2006. Peridroma saucia (Hübner), Variegated Cutworm Moth - Biodiversity of Great Smoky Mountains National Park. Discover Life in America - All Taxa Biodiversity Inventory. Web. 03 Apr. 2010. http://www.dlia.org/atbi/species/Animalia/Arthropoda/Insecta/Lepidoptera/Noctuoidea/Noctuidae/Noctuinae/peridroma_saucia.shtml
- Panella, N. Insect Migration. Colorado State University - Fort Collins. Web. 05 Apr. 2010. http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1995/panella.html
- ↑ Hahn, J., and Wold-Burkness, S. Cutworms in home gardens. University of Minnesota Extension. Web. 05 Apr. 2010. http://www.extension.umn.edu/distribution/horticulture/m1225.html 5.0 5.1
- University of Florida. N.d. Cutworms. U Florida IFAS - Mid-Florida Research and Education Center - Apopka / Orlando. Web. 25 Mar. 2010. http://mrec.ifas.ufl.edu/Foliage/entomol/ncstate/cater6.htm
- ↑ BC Ministry of Agriculture, Food and Fisheries. 2004. Cutworms - Tree Fruit Pests. Web. 29 Mar. 2010. http://www.agf.gov.bc.ca/cropprot/tfipm/cutworms.htm 7.0 7.1
- Peairs, F.B. 2010. Variegated Cutworm. Bugwood Wiki. Web. 25 Mar. 2010. http://wiki.bugwood.org/HPIPM:Variegated_Cutworm_FC