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Greasy or Black Cutworm

 

Agrotis ipsilon (Hufnagel) -- Lepidoptera:  Noctuidae

 

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       Species of moth

Agrotis ipsilon has been called the dark sword-grass or black cutworm, the greasy cutworm, the floodplain cutworm or ipsilon dart referring to the kind of environment and damage caused.  It is a small moth  that is found worldwide.   The moth's scientific name refers to black Y-shaped markings on its forewings.  The larvae are called cutworms because they cut plants and other crops. The larvae are very damaging as they feed on nearly all kinds of vegetables and grains.

 

 

 

 

 

 

 

 

      This species occurs seasonally as it travels north in springtime and south in autumn to avoid extreme temperatures in the summer and winter.  Therefore, reproduction occurs in the spring and early autumn.  The origin of black cutworm is not definitely known, but it is now found in many parts of the world, except in some tropical and very cold regions.  It is more widespread, and damaging, in the northern hemisphere than the southern hemisphere.  It annually reinvades temperate areas, overwintering in warmer or subtropical regions.  Long distance dispersal of adults has been reported from Europe, China, and North America. The basic pattern is to move north in the spring, and south in the autumn.  In the United States northward migration of moths during the spring can range 1000 km in two to four days with the northward winds.  In autumn southward winds assist migration.  Weather determines the number of annual generations.  In North America, there are one or two generations in Canada two to four further south.  However, the phenology of black cutworm is usually uncertain and variable due to the uncertainties associated with long range dispersal.

 

       Overwintering is in the pupal stage in most areas where overwintering occurs, but larvae persist throughout the winter in southern latitudes and a subtropical environment.  Pupae occasionally overwinter as far north as Tennessee, but cold temperatures restrict them further north.  Moths collected in the central region of the United States in March and April are mostly dispersing individuals that are past their peak egg production period, but they can still lay eggs in the area and form additional generations, including moths that disperse north into Canada.  Duration of the life cycle varies from 35 to 60 days.

 

       Adults are is quite large with a wingspan of 40 to 55 mm.  The forewing is dark brown.  The distal area is marked with a lighter irregular band, and a small black dash extends distally from the wing spot.  The hind wings vary white to gray, and the veins are marked with darker scales.  The adult preoviposition period is 7 to 10 days.  Moths prefer low-growing broadleaf plants for oviposition, but will also deposit eggs on dead plant material.  The egg is white in color initially, but gradually turns brown.  Its size is 0.43 to 0.50 mm high and 0.51 to 0.58 mm wide and is nearly spherical in shape, with a slightly flattened base.  The egg bears 35 to 40 ribs that radiate from the apex; the ribs are alternately long and short.  The eggs usually are deposited in clusters on foliage, with females depositing 1200 to 1900 eggs. Duration of the egg stage is three to six days.

 

       There are five to nine instars, with six to seven being most common.  Larval body length is considerably variable depending on the instar and temperature.  Larval development is strongly influenced by temperature, with the optimal temperature about 27°C. Humidity is less important, but instars one through five thrive best at higher humidities.  Larvae are rather uniformly colored on the dorsal and lateral surfaces, ranging from light gray or gray-brown to nearly black.  On some individuals, the dorsal region is slightly lighter or brownish in color, but the larva lacks a distinct dorsal band.  Ventrally, the larva tends to be lighter in color. Close examination of the larval epidermis reveals that this species bears numerous dark, coarse granules over most of its body.  The head is brownish with numerous dark spots.  Larvae usually remain on the plant until the fourth instar, when they shun light and hide in the soil during daytime.  In the latter instars they also tend to cut into plants at the soil surface, pulling the plant tissue below the ground.  Larvae can  be cannibalistic.  This species occurs often in many crops, and is one of the most common cutworms.  Despite the frequency of occurrence, they usually are not in great abundance, as is true of other cutworms and armyworms.

 

       Many species of natural enemies have been noted attacking black cutworms, but information on their relative importance is lacking.  In some Missouri studies sixty-nine percent parasitism was reported so natural enemies probably cause a significant cutworm reduction.  Among the parasitic wasps known to attack this cutworm species are Apanteles marginiventris (Cresson), Microplitis feltiae Muesebeck, Microplitis kewleyi Muesebeck, Meteorus autographae Muesebeck, Meterorus leviventris (Wesmael) (all Hymenoptera: Braconidae); Campoletis argentifrons (Cresson), Campoletis flavicincta (Ashmead), Hyposoter annulipes (Cresson), and Ophion flavidus Brulle (all Hymenoptera: Ichneumonidae).  Cutworm larvae that are parasitized by Meteorus leviventris (Wesmael) consume about 24% less foliage and cut about 36% fewer seedlings.  Therefore, considerable benefit may be derived from parasitism in addition to the eventual death of the larval populations.

 

REFERENCES:

 

Abdel-Gawaad, A. A & A. Y.  El-Shazli.  1971.  Studies on the common cutworm Agrotis ypsilon Rott. I. Life cycle and habits.  Zeitschrift fuer Angewandte Entomologie 68:  409-412.

 

Archer, T. L.,  G. L. Musick  &. R. L.  Murray.  1980.  Influence of temperature and moisture on black cutworm (Lepidoptera: Noctuidae) development and reproduction.  Canadian Entomologist 112:  665-673.

 

Boughton, A. J.,  L. C. Lewis & B. C. Bonning.  2001.  Potential of Agrotis ipsilon nucleopolyhedrosis for suppression of the black cutworm (Lepidoptera: Noctuidae) and effect of an optical brightener on virus efficacy. Journal of Economic Entomology 94:  1045-1052.

 

Busching, M. K. &  F. T. Turpin.  1976.  Oviposition preferences of black cutworm moths among various crop plants, weeds, and plant debris. Journal of Economic Entomology 69:  587-590.

 

Busching, M. K  &  F. T. Turpin.  1977.  Survival and development of black cutworm (Agrotis ipsilon) larvae on various species of crop plants and weeds.  Environmental Entomology 6:  63-65.

 

El-Heneidy, A. H.  &  Fawzia A. Hassanein.  1986.  Meteorus gyrator Thunberg and M. rubens Nees. (Hymenoptera: Braconidae), new recorded  parasitoids, on certain lepidopterous pests in Egypt.  Zeitschrift angewandete Entomologie 1986.

 

El-Heneidy, A. H. & Fawzia A. Hassanein.  1987.  Survey of the parasitoids of the Greasy Cutworm, Agrotis ipsilon Rott. (Lepidoptera: Noctuidae) in Egypt.  Anz. Schȁdling. Pflanzenschutz, Umweltschutz 60:  155-157, Germany.

 

El-Heneidy, A. H.  &  Fawzia A. Hassanein.  1989.  Biological notes on  Meteorus rubens Nees. (Hymenoptera: Braconidae), a larval parasitoid of the  Greasy Cutworm, Agrotis ipsilon Rott.  Agric. Res. Rev., 67 (1):  43-47, Egypt.

 

Harris, C. R., J. H. Mazurek & G. V. White.  1962.  The life history of the black cutworm, Agrotis ipsilon (Hufnagel), under controlled conditions.  Canadian Entomologist 94:  1183-1187.

 

Schoenbohm, R. B.  &  F. T. Turpin.  1977.  Effect of parasitism by Meteorus leviventris on corn foliage consumption and corn seedling cutting by the black cutworm.  Journal of Economic Entomology 70:  457-459.

 

Showers, W. B.,  A. J. Keaster, J. R. Raulston, W. H. Hendrix, M. E. Derrick,  M. D. McCorcle, J. F. Robinson, M. O. Way,  M. J. Wallendorf & J. L. Goodenough.  1993.  Mechanism of southward migration of a noctuid moth [Agrotis ipsilon (Hufnagel)]:  a complete migrant.  Ecology 74:  2303-2314.

 

Showers, W. B., R. H. Smelser, A. J. Keaster, F. Whitford, J. F. Robinson, J. D. Lopez & S. E. Taylor.  1989.  Recapture of marked black cutworm (Lepidoptera: Noctuidae) males after long-range transport.  Environmental Entomology 18:  447-458.

 

Smelser, R. B., W. B. Showers, R. H. Shaw & S. E. Taylor.  1991.  Atmospheric trajectory analysis to project long-range migration of black cutworm (Lepidoptera: Noctuidae) adults.  Journal of Economic Entomology 84:  879-885.

 

Story, R. N. & A. J. Keaster.  1982a.  The overwintering biology of the black cutworm, Agrotis ipsilon, in field cages (Lepidoptera: Noctuidae).  Journal of the Kansas Entomological Society. 55:  621-624.

 

Story, R. N. & A. J. Keaster.  1982b.  Temporal and spatial distribution of black cutworms in Midwest field crops.  Environmental Entomology 11:  1019-1022.

 

Story, R. N. & A. J. Keaster.  1983.  Modified larval bait trap for sampling black cutworm (Lepidoptera: Noctuidae) populations in field corn.  Journal of Economic Entomology 76:  662-666.

 

Story, R. N., F. J. Sundstrom & E. G.  Riley.  1983.  Influence of sweet corn cultivar, planting date, and insecticide on corn earworm damage.  Journal of the Georgia Entomological Society 18:  350-353.

 

Story, R. N., A. J. Keaster, W. B. Showers  &  J. T. Shaw.  1984.  Survey and phenology of cutworms (Lepidoptera: Noctuidae) infesting field corn in the midwest.  Journal of Economic Entomology 77:  491-494.