[4] 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.

[5] 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.

[1] As polygamous insects, females release sex pheromones and choose multiple males as mates.

[7][8] 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.

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

[1] 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.

See also Hacker et al.[9] Pupation occurs underground in a silken case produced by the larvae.

Black dots line the anterior edge of the forewings, making them look very pointed.

The orbicular and reniform stigmata are pale or yellowish, the latter with a white dot at lower end.

These include ground beetles, who share the same habitat in the soil, in addition to predatory bugs, ants, and spiders.

On average, this behavior is displayed around 4–6 days after emergence; age of calling onset is determined by ambient temperature and photoperiod.

Low temperatures and short photoperiods delay the calling period, but higher temperatures and long photoperiods trigger calling period sooner after emergence[6] These are consistent with the yearly changes in the behavior of P. unipuncta: the moth is in migration in the fall and spring seasons, and P. unipuncta prefer to mate in the summer.

The corpora allata is an endocrine gland that when removed, causes pheromone synthesis and calling behavior to cease.

However, these scent organs are not necessary for copulation as a significant portion of females will still mate with males with no hairpencils.

The delay can be attributed to the time it takes to transfer sperm to the duplex, an accessory gland.

When (Z)-11-hexadecenal, a component found in the sex pheromones of S. nonagrioides females, was added to the lures, the M. unipuncta males were less attracted.

Therefore, the males' ability to detect certain acetates in the pheromones serves as a reproductive isolating mechanism and prevents cross-species mating.

In response to female sex pheromones, males may produce a low-frequency trembling noise.

This species prefers grass weeds, (such as Urochloa ramosa,[15]) but when those are depleted, they quickly move to crops.