Honey locust moths that emerge in June and after are called the “summer form.” The forewing upperside ranges from rust-colored to orangish to yellow-tan. Usually, there is a postmedian line (running between the midpoint and the wing edge) that bends in toward the hind part of the forewing. This line touches the leading edge of the wing in front of the outer tip. In the cell (a region at the core of the forewing, near the leading edge), there are two small white spots. The hindwing lacks lines but usually has some rosy or reddish shading.
There is a lot of variation in the markings of this species, based on season and individual genetics. In the spring generation, the ground color of the forewing is gray, often with heavier sprinkling of small dark specks. As the season progresses, moths with intermediate coloration occur until June, when the brighter, more colorful summer form predominates.
Larvae, in their mature stage, are green and sprinkled with white specklike tubercles. The second and third thoracic (behind the head) segments have two pairs of reddish horns. There is a reddish taillike horn. There are sharp, pearl-colored spines on the abdominal section (behind the thorax). A white stripe, often bordered by a red stripe, runs down each side. The head is green with yellow bands.
Similar species: The bisected honey locust moth (S. bisecta) is very similar but is usually less abundant. It is generally larger, its postmedian line is straighter and reaches the outer tip of the wing, and the white spots in the forewing cell are absent. It has the same food plants and range as the honey locust moth. At one point they were considered different forms of the same species.
Wingspan: 1¾–2¾ inches.
Habitat and Conservation
Honey locust moths are found where there are honey locust and Kentucky coffee trees, which means nearly any woodland or forest in the state. You may also see them around lights at night.
As the name implies, the larval food plant is honey locust. The caterpillars also eat the foliage of Kentucky coffee tree. The adults of this (and other members of the giant silkworm family) have reduced mouthparts and cannot eat as adults.
Common breeding resident.
Adults of this species fly between mid-April and September, and there are three broods. Females are larger than males. Like other members of this family, they have a limited time as adults — usually, they mate the same night they emerge as adults. The next day, females deposit eggs, singly or in twos, on the leaves of honey locust or Kentucky coffee tree — their host plants. Larvae can hatch within a week, and these can eat, grow, molt, pupate, and complete the cycle within six weeks. The larvae pupate in the ground. This species overwinters in the pupal form.
The primary food plant of this moth, the honey locust, is famous for its large, imposing thorns. A thornless variety of the tree is very popular as a street tree and in landscape plantings. The many planted thornless specimens must attract at least some honey locust moths to the suburbs and cities.
This moth belongs to a subfamily of saturniids called the royal moths (Ceratocampinae). One of the characteristics of this subfamily is that the antennae of males are quadripectenate (featherlike, with each branch split into two parts) at the basal half or two-thirds of the antenna, with the outer portion simple (not featherlike). Males use their elaborate antennae to detect and follow the pheromones (sex-attraction scents) given off by the female. These moths don’t live long as adults, and if they are to reproduce, they must find each other quickly.