Mythimna unipuncta

Mythimna unipuncta, the true armyworm moth, white-speck moth, common armyworm, or rice armyworm, is a species of moth in the family Noctuidae. The species was first described by Adrian Hardy Haworth in 1809. Mythimna unipuncta occurs in most of North America south of the Arctic, as well as parts of South America, Europe, Africa, and Asia. Although thought to be Neotropical in origin, it has been introduced elsewhere, and is often regarded as an agricultural pest. They are known as armyworms because the caterpillars move in lines as a massive group, like an army, from field to field, damaging crops.

The true armyworm has a distinct migration pattern in which they travel north in the spring and south in the fall to ensure that mating occurs in a favorable environment in the summer. While progressing through the life cycle stages of egg, larva, pupa, and adult, this species must avoid attack from predatory bugs, birds, wasp and fly parasitoids, and bacterial and fungal diseases. As polygamous insects, females release sex pheromones and choose multiple males as mates. The production and release of the pheromones are influenced by temperature, photoperiod, and the juvenile hormone. Hearing is an important sense for the true armyworm, necessary for mating and evading bat predation.

M. unipuncta are commonly found around the world including the Americas, southern Europe, central Africa, and western Asia. In North America, they inhabit areas east of the Rocky Mountains and in northern Canada.

Larvae feed and damage on a variety of Graminae (weedy grasses) and other crops.

Adults feed on the nectar of various types of flowers and will eat ripe or decaying fruit.

In a given year, there can be two to three generations, each generation requiring 30–50 days to complete.

Adults oviposit in groups of 2 to 5 rows on dry leaves and grass, especially between the leaf sheath and blade. Females may deposit up to 80 eggs per cluster, leading to highly dense larvae populations. Total reproductive capacity for females is between 500-1500 eggs. The egg stage lasts on average 3.5 days in warmer weather and 6.5 days in cooler weather.

The eggs appear to be a white or yellowish color but change to a gray hue right before eclosion. A sticky material on the surface of the egg sticks to surrounding foliage and helps hide the eggs.