Armyworms are insect pests that can cause significant damage to crops, including eggplants. These caterpillars, the larvae of several moth species, feed on a variety of plants, including sugarbeet, alfalfa, beans, eggplants, and tomatoes, as well as several types of weeds.
In the winter and spring, armyworm populations tend to be concentrated on weeds, but as the weather warms up and host crops begin to grow, moths lay their eggs on the young leaves of these plants. Once the eggs hatch, the larvae feed together near the egg cluster before dispersing as they grow.
Armyworms Management in Eggplant
The Life Cycle of Armyworms
- The life cycle of armyworms begins when they overwinter as pupae in the soil. Adult moths emerge from the soil from March to July and mate before laying eggs on host crops. Depending on environmental conditions, the eggs hatch into small larvae that feed on the host plant for 5 to 8 weeks.
- As the larvae mature, they gradually disperse from their original egg cluster and continue feeding on the host plant, causing significant damage. Once they have finished feeding, the mature larvae enter the pupal stage in the soil, where they will remain until they emerge as adult moths in the following spring.
- There are typically two generations of armyworms yearly, with the second generation hatching in late summer or early fall. These larvae feed until early October before entering the pupal stage to overwinter in the soil.
Identification of Armyworms in Eggplant Field
- Armyworm moths are grey and brown in adult form, with a 1.25 to 1.5 inches wingspan. Depending on the species, they may also have grey or tan-colored patterns. On their wings, they feature a recognizable “V-shaped marking.
- Egg: Beet armyworm eggs are ridged, pale green to pink, and in a mass wrapped in a substance that resembles grey cotton. Often, they are arranged in groups on the undersides of leaves.
- Armyworm larvae are 1.25 to 1.5 inches long and come in various colors, including olive green, light green, and yellow, as well as grey with dark patterns and yellow with dark grey or black markings. Their skulls have a characteristic inverted “Y” shape.
- Pupa: Armyworm pupae are about 0.75 inches long and reddish-brown. They are usually found in the soil or leaf litter at the base of host plants.
Damage Symptoms of Armyworms in Eggplant Fields
- Defoliation: Armyworms can quickly defoliate eggplant plants, stripping them of their leaves and reducing their ability to produce energy through photosynthesis.
- Fruit loss: As the fruit forms, armyworms may feed on the calyx, causing damage and scarring to small fruit. This can result in reduced yield and lower-quality products.
- Plant stunting: Severe armyworm infestations can cause eggplant plants to stunt, reducing their growth and overall productivity.
- Visible feeding damage: Armyworm larvae can leave visible feeding damage on the leaves and fruit of eggplants, including ragged holes and missing tissue.
- Fecal matter: Armyworms leave behind fecal matter as they feed, which can accumulate on the leaves and fruit of eggplants, making them unattractive and unsellable