Corn Moth - Caterpillars Attack Agricultural Fields

Agricultural fields are constantly attacked by pests. One of them is a corn moth or a grass moth. This butterfly is a polyphage that damages 250 species of various plants. From the life of its larvae, cereals, oilseeds and legumes suffer. The pest has spread throughout Eurasia; it develops in temperature conditions exceeding 20⁰ in the summer months.

The appearance of a moth

Ognevka corn - a butterfly that inhabits various cultivated plants. The wingspan is 24-32 mm, the color varies from brownish-gray to yellow. Fore wings have transverse brown stripes and spots. At rest, the butterflies sit on the underside of the leaves, folding their wings in a roof-like fashion. The whole family of herbal moths, to which the corn moth belongs, is a pest of crops. In insects, sexual dimorphism is clearly seen. There are several signs to distinguish between males and females:

• the females are larger than the male in size;
• the coloration of males is darker;
• tibia of middle legs covered with serrated scales;
• in females of the abdomen of six segments, and in males - of seven.

Butterfly habitat - Europe, Central Asia, North Africa and America. The period of their activity is evening and night. In search of food, they fly up to three kilometers.

Information. The life expectancy of an adult corn moth is 5-20 days.

Breeding

Stem corn moth Ostrinia nubilalis refers to insects with a complete transformation. Intensive reproduction of the pest is observed in periods with high humidity. With drought, their amount decreases. In most of the inhabited territory, 1 generation of butterflies is replaced per season, but in the North Caucasus, conditions contribute to two-fold breeding. The most favorable region for the moth is Central Asia, 3 generations are replaced here.

Ognevki appear in mid-late June. After 4-5 days after departure, the female lays eggs on the underside of the leaves. This process coincides with the flowering of corn. Egg laying lasts 2-3 weeks, during which time the insect produces 250-600 pieces, the most prolific ones - 1200. In one clutch, 10-15 flat cream eggs. They are laid like tiles, poured on top with sticky secretions.

At high humidity and moderate temperature, 3-4 days are enough for the development of the embryo, in poor conditions it takes 2 weeks. Young larvae of the first and second age feed on leaves, eating large longitudinal holes. In addition, they penetrate into the inflorescences and tops of the stalks of corn. After birth, the caterpillars are weak and vulnerable, at this time a significant part of the offspring dies. The larva size is 20–25 mm; the color is yellow with a pink tint. The head is brown, on the back is a dark longitudinal stripe. Young caterpillars migrate not only along the plant on which they were born, but also move to neighboring stems. At an older age, the larvae eat into the middle of the stem and cob. They get nutritious protein foods and quickly gain weight. In the process of feeding, labyrinths are created from passages and holes.

Information. Pest control is complicated by the prolonged period of the summer of butterflies, which is 45 days.At the same time, insects of different ages are found.

Pest Insect Life Cycle

In its development butterfly fire goes through all stages of development from the egg to the imago. Despite the fact that adults need food, caterpillars do harm to cultivated crops. In the process of development, they molt 4 times. Larvae of the last fifth age remain wintering. The caterpillar stage takes from 14 to 60 days. With the onset of cold weather, the larvae descend from the upper and middle parts of the stalks of corn or another plant into the lower section. In the cavity of the stem, they build a protective chamber, covering themselves on two sides with pieces of the plant. Insects are amazingly resistant to frost, temperature -30 can destroy them⁰established for a whole month.

Attention. After harvesting in the stubble of millet and corn, you can find many wintering caterpillars.

Turning into a chrysalis occurs in the spring, when at least + 15 is established⁰. In May, the caterpillar gnaws at a passage in its chamber, so that the butterfly that appears can easily get out of the cob. The larva creates a web cocoon inside the stem. A pupa needs warmth and high humidity for development. After 10-14 days, a moth flies out, in adverse conditions - after 50. By the weight of the pupa, the sex of the individual can be determined - large cocoons of 100 mg are found in females, males weigh 60 mg.

Track Injury

A corn stalk moth cuts through the fibers inside the plant stem. The culture begins to dry, the seed yield decreases. The second generation of moths begins in August. The development of larvae occurs in the same way as in the first generation. They are embedded in the petioles of leaves, panicles of corn, undermine the stem. In places of thinning, cobs and stems break. Weakened plants are easily affected by pathogenic fungi. Fusarium, gray rot and mold appear after the caterpillars.

Fire fighting methods

To prevent significant crop losses (up to 10%), which are a consequence of the life of the moths butterfly, a set of measures is applied.

Biological products

The moth has many natural enemies. In the fields of corn, trichograms are populated. These are parasites riders, their offspring grow on the eggs of butterflies. The number of stem moths is reduced by birds, for example, black-headed.

Agrotechnical measures

Agrotechnical measures are effective in the fight against a pest:

• autumn plowing;
• low cut when harvesting corn;
• destruction of weed and plant debris;
• mechanical damage to stubble, allowing the destruction of wintering larvae.

Chemicals

Without chemical preparations, insects cannot be destroyed; plants are treated twice with insecticides - “Karate”, “Chlorophos”. Spraying and distribution of granules is carried out after the appearance of the first caterpillars and during the period of their mass distribution.