Wax moths are a common challenge for those managing beeswax or stored comb, as their larvae can cause destruction. These insects progress through four distinct life stages—egg, larva, pupa, and adult—each with unique physical characteristics. Identifying the different stages is the first step in addressing a potential infestation. The two most common species, the Greater and Lesser Wax Moths, share similarities but are distinguished by specific visual cues at maturity.
Visual Characteristics of the Adult Moth
The mature wax moth is a small, winged insect that generally exhibits a drab appearance. Adult moths of both species range in body length from 10 to 19 millimeters, with the color scheme tending toward pale brown, gray, or mottled shades. When at rest, the forewings are held tightly in a characteristic roof-like posture over the body.
The adults possess reduced mouthparts and do not consume food or water, meaning they are not responsible for the damage associated with these pests. Their primary role is reproduction, with females seeking out dark crevices to lay their eggs. Both species are typically nocturnal and may be observed flying or quickly scuttling away when exposed to light.
Identifying the Larva and Pupa Stages
The larval stage, or the wax worm, is the phase responsible for feeding and damaging wax and comb. Newly hatched larvae are small and creamy white, gradually turning grayish or mushroom-gray as they mature. The larva has a distinct, dark brown or reddish head capsule and a segmented body with three pairs of legs near the head.
Fully grown larvae reach 20 to 28 millimeters, actively burrowing tunnels through the comb and lining these passages with silken webbing. This silk, combined with granular, dark fecal matter known as frass, is a clear sign of their presence. Before transforming, the mature larva spins a dense, tough cocoon of white or off-white silk.
This cocoon is often cemented firmly to the wooden parts of a structure, sometimes in a boat-shaped cavity the larva gnaws out. Inside this protective casing, the insect enters the pupal stage, transforming into a moth. The pupa is typically yellowish-brown to dark reddish-brown, measuring 11 to 20 millimeters in length.
Key Visual Differences Between Species
The Greater Wax Moth, Galleria mellonella, and the Lesser Wax Moth, Achroia grisella, are differentiated in their adult form based on size and wing markings. The Greater Wax Moth is the larger of the two, with a body length of 13 to 19 millimeters and a wingspan up to 40 millimeters. Its forewings are usually pale brown or gray with reddish-brown mottling, sometimes displaying a bronze tinge, especially on the hind edges.
Male Greater Wax Moths have a distinctive feature: the outer margin of their forewings is scalloped or concave. In contrast, the Lesser Wax Moth is smaller, measuring 10 to 13 millimeters long with a wingspan of 11 to 14 millimeters. The Lesser Wax Moth tends to have a uniform silvery-gray or tan coloration and may have a distinct yellow head.
The larval stages also exhibit a size difference; the Greater Wax Moth larva grows up to 28 millimeters, compared to the Lesser Wax Moth larva, which reaches about 20 millimeters. While both larvae are pale, the Lesser Wax Moth larva may sometimes show a faint pink or salmon-pink tinge as it ages. Identification relies on these subtle yet consistent differences in size, wing shape, and color patterns.