Cutworms are moth larvae 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. Cutworms are not worms, biologically speaking, but caterpillars.
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. For example, it has been suggested that in South Africa for one, Agrotis segetum is the second worst pest of maize. [1]
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. [2]
The term cutworm applies mainly to larvae of various species in several genera within the Noctuidae, a large family of moths; however many noctuid species are not cutworms, and some moths whose larvae have essentially the same habit, which justifies calling them cutworms, are not noctuids. The turnip moth ( Agrotis segetum ), Agrotis ipsilon , Agrotis exclamationis , and other members of this genus, are well-known noctuids whose larvae are very damaging. 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. One of the most common garden pests is the variegated cutworm ( Peridroma saucia ), which can defoliate entire gardens and fields in a matter of days. [3]
Cutworms are usually green, brown, grey, or yellow soft-bodied caterpillars, often with longitudinal stripes, up to 1 inch (2.5 centimeters) 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 larvae or as pupae. 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. [1] 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. [1]
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 surviving 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. [1]
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. [4] [5] Alternatively, a gallon planter with both ends removed may be used. [6]
Cutworms are hosts for numerous parasitoid wasps and flies, including species of Braconidae, Ichneumonidae, Tachinidae and Eulophidae, with rates of parasitism as high as 75–80 percent. [7] [8]
Lepidoptera is an order of insects that includes butterflies and moths. About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described species of living organisms. It is one of the most widespread and widely recognizable insect orders in the world. The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought, and is among the four most speciose orders, along with the Hymenoptera, Diptera, and Coleoptera.
Nicotiana is a genus of herbaceous plants and shrubs in the family Solanaceae, that is indigenous to the Americas, Australia, Southwestern Africa and the South Pacific. Various Nicotiana species, commonly referred to as tobacco plants, are cultivated as ornamental garden plants. N. tabacum is grown worldwide for the cultivation of tobacco leaves used for manufacturing and producing tobacco products, including cigars, cigarillos, cigarettes, chewing tobacco, dipping tobacco, snuff, and snus.
The Noctuidae, commonly known as owlet moths, cutworms or armyworms, are a family of moths. They are considered the most controversial family in the superfamily Noctuoidea because many of the clades are constantly changing, along with the other families of the Noctuoidea. It was considered the largest family in Lepidoptera for a long time, but after regrouping Lymantriinae, Catocalinae and Calpinae within the family Erebidae, the latter holds this title now. Currently, Noctuidae is the second largest family in Noctuoidea, with about 1,089 genera and 11,772 species. This classification is still contingent, as more changes continue to appear between Noctuidae and Erebidae.
Helicoverpa zea, commonly known as the corn earworm, is a species in the family Noctuidae. The larva of the moth Helicoverpa zea is a major agricultural pest. Since it is polyphagous during the larval stage, the species has been given many different common names, including the cotton bollworm and the tomato fruitworm. It also consumes a wide variety of other crops.
The bogong moth is a temperate species of night-flying moth, notable for its biannual long-distance seasonal migrations towards and from the Australian Alps, similar to the diurnal monarch butterfly. During the autumn and winter it is found in southern Queensland, western New South Wales, western Victoria, and also in South and Western Australia. Adult bogong moths breed and larvae hatch during this period, consuming winter pasture plants during their growth. During the spring, the moths migrate south or east and reside in mountains such as Mount Bogong, where they gregariously aestivate over the summer until their return towards breeding grounds again in the autumn.
The pine processionary is a moth of the subfamily Thaumetopoeinae in the family Notodontidae, known for the irritating hairs of its caterpillars, their processions, and the economic damage they cause in coniferous forests. The species was first described scientifically by Michael Denis and Ignaz Schiffermüller in 1775, though it was known to the ancients, with remedies described by Theophrastus, Dioscorides and Pliny the Elder. Its processionary behaviour was described in 1916 by the French entomologist Jean-Henri Fabre. It is one of the most destructive species to pines and cedars in Central Asia, North Africa and southern Europe.
Agrotis segetum, sometimes known as the turnip moth, is a moth of the family Noctuidae. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775. It is a common European species and it is found in Africa and across Eurasia except for the northernmost parts.
The oak processionary is a moth whose caterpillars can be found in oak forests, where they feed on oak leaves, causing significant damage. They travel in nose-to-tail processions, often arrow-headed, with a leader followed by rows of several caterpillars abreast. They are a human irritant because of their venomous setae, which can cause skin irritation and asthma. The species was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae.
Manduca quinquemaculata, the five-spotted hawkmoth, is a brown and gray hawk moth of the family Sphingidae. The caterpillar, often referred to as the tomato hornworm, can be a major pest in gardens; they get their name from a dark projection on their posterior end and their use of tomatoes as host plants. Tomato hornworms are closely related to the tobacco hornworm Manduca sexta. This confusion arises because caterpillars of both species have similar morphologies and feed on the foliage of various plants from the family Solanaceae, so either species can be found on tobacco or tomato leaves. Because of this, the plant on which the caterpillar is found does not indicate its species.
The African armyworm, also called okalombo, kommandowurm, or nutgrass armyworm, is a species of moth of the family Noctuidae. The larvae often exhibit marching behavior when traveling to feeding sites, leading to the common name "armyworm". The caterpillars exhibit density-dependent polyphenism where larvae raised in isolation are green, while those raised in groups are black. These phases are termed solitaria and gregaria, respectively. Gregaria caterpillars are considered very deleterious pests, capable of destroying entire crops in a matter of weeks. The larvae feed on all types of grasses, early stages of cereal crops, sugarcane, and occasionally on coconut. The solitaria caterpillars are less active and undergo much slower development. The species is commonly found in Africa, but can also be seen in Yemen, some Pacific islands, and parts of Australia. African armyworm outbreaks tend to be devastating for farmland and pasture in these areas, with the highest-density outbreaks occurring during the rainy season after periods of prolonged drought. During the long dry seasons ("off-season"), the population densities are very low and no outbreaks are seen.
Agrotis is a genus of moths of the family Noctuidae. The genus was erected by Ferdinand Ochsenheimer in 1816. A number of the species of this genus are extinct.
Agrotis ipsilon, the dark sword-grass, black cutworm, greasy cutworm, floodplain cutworm or ipsilon dart, is a small noctuid moth found worldwide. The moth gets its scientific name from black markings on its forewings shaped like the letter "Y" or the Greek letter upsilon. The larvae are known as "cutworms" because they cut plants and other crops. The larvae are serious agricultural pests and feed on nearly all varieties of vegetables and many important grains.
The poko noctuid moth is a moth in the family Noctuidae. The species was first described by Arthur Gardiner Butler in 1881.
Acronicta rumicis, the knot grass moth, is a species of moth which is part of the genus Acronicta and family Noctuidae. It was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. It is found in the Palearctic region. A. rumicis lives and feeds on plants located in wide-open areas. At its larval stage, as a caterpillar, it causes such a large impact as a crop pest that it has received much attention and research. A. rumicis feeds on maize, strawberries and other herbaceous plants.
Peridroma saucia, the pearly underwing or variegated cutworm, is a moth of the family Noctuidae. The species was first described by Jacob Hübner in 1808. It is found in North and South America, Europe, Asia and Africa. The variegated cutworm feeds on many plants, especially common fruits and vegetables. The moth undergoes two to four generations per year. The development of the moth slows in colder temperatures, indicative of its migratory nature. All stages of the life cycle have a developmental threshold for temperature. The moth is known to migrate to the northern regions during warmer months, returning to the southern regions when the climate becomes colder.
The zebra caterpillar is the larva of an American noctuid moth that feeds on cabbages, beets and other cultivated plants.
Spodoptera eridania is a moth that is known to be a pest. They are one of the most important defoliators in the tropical and subtropical regions of the western hemisphere that feed heavily on plants while they are young, often resulting in skeleton leaves on their food plants. They are also heavy feeders on tomato in Florida. There is a lot of development in producing pesticides against the S. eridania, specifically a neem-based pesticide that can result in smaller and prolonged development. The wingspan is 33–38 mm. Adults are on wing year-round. The larvae feed on various weeds but prefer Amaranthus species and Phytolacca americana.
Lespesia archippivora is a species of tachinid fly, which, like all tachinids, are parasitoids of other arthropods. L. archippivora lives in the body of its host resulting in its death. This is not uncommon since it is estimated that about 10% of all insects are parasitoids. L. archippivora is a generalist and able to infect at least 25 lepidopteran species in addition to one species of Hymenoptera. It is common in North America and other species exist worldwide. One study suggests the species is bivoltine.