Cutworm
Encyclopedia
Cutworms are not worm
s, biologically speaking, but caterpillars; they are moth larva
e that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it down; hence the name cutworm.
for one, Agrotis segetum is the second worst pest of maize.
Note that the cutworm mode of feeding is only one version of a strategy of avoiding predators and parasitoids by day. Many other caterpillars, including Noctuidae and some kinds of processionary caterpillars
, come out at night to feed, but hide again as soon as the sky begins to grow lighter. Some, for example Klugeana
philoxalis attack low-growing forbs such as Oxalis
in the dark, and drop to the ground as soon as a light is flashed on them. Others will climb trees such as species of Acacia nightly, leaving trails of silk, but they leave individual trails, not common trails like processionary caterpillars. The fruit-piercing moth Serrodes partita similarly lives under litter beneath its food plant, the tree Pappea capensis
, a large family of moths; however, many Noctuid species are not cutworms, and some moths whose larvae have the essentially the same habit, which justifies calling them cutworms, are not Noctuids. The larva
e of the Turnip moth
, (Agrotis segetum, Agrotis ipsilon, Agrotis exclamationis), are well-known Noctuids whose larvae are very damaging cutworms. Cutworms are notorious agricultural
and garden pests. They are voracious leaf, bud, and stem feeders and can destroy entire plants. They get their name from their habit of "cutting" off a seedling at ground level by chewing through the stem. Some species are subterranean and eat roots.
In many climates, cutworms will winter under the soil, either as final instar
larvae or as pupa
e. This affords farmers an opportunity for control. Winter ploughing will kill many of the pests, and expose many more to predators. In suitable areas this is a powerful means of control, for example in grain fields. The same principle permits some domestic gardeners to kill the caterpillars without the problems associated with the use of pesticides; the first line of control can be to till the soil some weeks before planting to destroy any dormant larvae. Also, at any time during the season, if the population has been reasonably well controlled, but there are signs of localised cutworm attack, the domestic gardener may be able to deal with the problem simply by digging the soil and wet foliage to about 2 inches deep, and killing the caterpillars manually.
Starvation also can be effective when it is practical to keep weeds down before the growing season, by systematic cultivation. Together with reducing manure and compost, relying instead on other forms of fertilizer, this can improve control by discouraging cutworm moths from laying their eggs, and depriving the larvae of food.
Baits also can be effective where starvation strategies have been applied reasonably successfully; a sweetened bran mash containing a suitable stomach poison can be very effective against the small numbers of ssurviving caterpillars. The mash should be too crumbly and too thinly scattered to leave any lumps on the ground that domestic animals or desirable wild animals might otherwise pick up.
Because cutworms attack the first part of the plant they find at night, plant collars made of aluminum, or even cardboard barriers, can offer effective protection.
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s, biologically speaking, but caterpillars; they are moth larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it down; hence the name cutworm.
Feeding and hiding
Cutworm larvae vary in their feeding behaviour; some remain with the plant they cut down and feed on it, while others often move on after eating a small amount from a felled seedling; such a wasteful mode of feeding results in disproportionate damage to crops. Cutworms accordingly are serious pests to gardeners in general, but to vegetable and grain farmers in particular. It has been suggested that in South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
for one, Agrotis segetum is the second worst pest of maize.
Note that the cutworm mode of feeding is only one version of a strategy of avoiding predators and parasitoids by day. Many other caterpillars, including Noctuidae and some kinds of processionary caterpillars
Thaumetopoeidae
Thaumetopoeidae is a small family of moths in the order Lepidoptera. The genera in this family have been historically treated as a subfamily within Notodontidae instead....
, come out at night to feed, but hide again as soon as the sky begins to grow lighter. Some, for example Klugeana
Klugeana
Klugeana is a genus of moths of the Noctuidae family.The South African species Klugeana philoxalis has been proposed as being of interest as a possible biocontrol agent for dealing with invasive Oxalis pes-caprae in countries where it is a problem. Like many Noctuids, Klugeana philoxalis has...
philoxalis attack low-growing forbs such as Oxalis
Oxalis
Oxalis is by far the largest genus in the wood-sorrel family Oxalidaceae: of the approximately 900 known species in the Oxalidaceae, 800 belong here...
in the dark, and drop to the ground as soon as a light is flashed on them. Others will climb trees such as species of Acacia nightly, leaving trails of silk, but they leave individual trails, not common trails like processionary caterpillars. The fruit-piercing moth Serrodes partita similarly lives under litter beneath its food plant, the tree Pappea capensis
Species and habits
The term cutworm applies mainly to larvae of various species in the NoctuidaeNoctuidae
The Noctuidae or owlet moths are a family of robustly-built moths that includes more than 35,000 known species out of possibly 100,000 total, in more than 4,200 genera. They constitute the largest family in the Lepidoptera....
, a large family of moths; however, many Noctuid species are not cutworms, and some moths whose larvae have the essentially the same habit, which justifies calling them cutworms, are not Noctuids. The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of the Turnip moth
Turnip Moth
The Turnip Moth is a moth of the family Noctuidae. It is a common European species, but it is also found in Asia and Africa, very likely having been spread by the international trade in nursery stock...
, (Agrotis segetum, Agrotis ipsilon, Agrotis exclamationis), are well-known Noctuids whose larvae are very damaging cutworms. Cutworms are notorious agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
and garden pests. They are voracious leaf, bud, and stem feeders and can destroy entire plants. They get their name from their habit of "cutting" off a seedling at ground level by chewing through the stem. Some species are subterranean and eat roots.
Appearance and control
Cutworms are usually green, brown, grey, or yellow soft-bodied caterpillars, often with longitudinal stripes, up to 2.5 cm (1 inch) in length. There are many variations among the genera. There also are variations in their biology and control, so the following extension material must be applied only as appropriate to the region.In many climates, cutworms will winter under the soil, either as final instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
larvae or as pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
e. This affords farmers an opportunity for control. Winter ploughing will kill many of the pests, and expose many more to predators. In suitable areas this is a powerful means of control, for example in grain fields. The same principle permits some domestic gardeners to kill the caterpillars without the problems associated with the use of pesticides; the first line of control can be to till the soil some weeks before planting to destroy any dormant larvae. Also, at any time during the season, if the population has been reasonably well controlled, but there are signs of localised cutworm attack, the domestic gardener may be able to deal with the problem simply by digging the soil and wet foliage to about 2 inches deep, and killing the caterpillars manually.
Starvation also can be effective when it is practical to keep weeds down before the growing season, by systematic cultivation. Together with reducing manure and compost, relying instead on other forms of fertilizer, this can improve control by discouraging cutworm moths from laying their eggs, and depriving the larvae of food.
Baits also can be effective where starvation strategies have been applied reasonably successfully; a sweetened bran mash containing a suitable stomach poison can be very effective against the small numbers of ssurviving caterpillars. The mash should be too crumbly and too thinly scattered to leave any lumps on the ground that domestic animals or desirable wild animals might otherwise pick up.
Because cutworms attack the first part of the plant they find at night, plant collars made of aluminum, or even cardboard barriers, can offer effective protection.