Orgyia detrita (Fir Tussock Moth)

 

04/03/2026

 

Samuel Clifford

 

This moth species is a part of the family Erebidae and was formerly in the family Lymantriidae. That family was recategorized as a Subfamily under Erebidas and is now called Lymantriidae. I viewed this specific species in Savannah GA. I am concerned of a miss identification as a relative of this species is fairly common in the region. That species being Orgyia leucostigma (White-marked tussock moth).

Lighter Form

Darker Form

 

The pupae appear hairy & the males have longer antennae than the females. Their wings also are longer. Adult Moths exhibit sexual dimorphism. Males are smaller & have a dull color compared to the females. When resting they hold their legs (first pair) in an outstretched position. In fact, the name Orgyia is Greek for "the length of the outstretched arms.”

 

Orgyia species are Frown to cause dermatitis in younger children. Dermatitis is caused by urticating setae containing histamine‑like compounds. Known predators of Orgyia include large ground beetles and polistes paper wasps. Bird predation is low because of the irritating setae. 

Sources

 

Hall, Donald W., and Lyle Buss. Fir Tussock Moth Orgyia detrita Guérin-Méneville, 1831 (Lepidoptera: Erebidae: Lymantriinae). EDIS, vol. 2014, no. 2, University of Florida IFAS Extension, 2014, https://doi.org/10.32473/edis-in1032-2014.



The caterpillar or larvae I saw had a grayish body with tan tufts & orange tinted warts. That gave me the identification of Orgia detrita as Orgyia leucostigma has more bright white tufts & yellow warts. There are two forms of Orgyia detrita, a light form that has a bright yellow hue & a dark form. Both detrita & leucostigma have a bright orange head especially when compared to the relative definita which has a tan or yellow head.

 

The cocoons of the Orgyia detrita are constructed of silk & setae that come directly From the caterpillars. I actually was able to view one individual in an early cocoon. All the individuals I viewed were on the side of a building & constructed their cocoons under the soffits of the building or in a crevice.

 

 

Region: 

 

Orgyia detrita is most strongly associated with the Southeastern Coastal Plain, where it is especially common in Florida and extends northward into coastal Georgia, including the Savannah region, and occasionally into southern South Carolina during warm years. Its larvae feed primarily on live oak (Quercus virginiana), a dominant tree in these coastal habitats, and this host preference is one of the clearest ecological distinctions between O. detrita and its more widespread relative O. leucostigma. 

 

Life Cycle :

 

  • They start out as eggs and are laid in Clusters. The eggs begin to hatch in late February and the newly hatched larvae then feed on the left over egg mass & use it for silk for dispersal.

 

  • During the larvae stage the larvae increasingly get bigger in size through a series of molts. When they reach maturity they begin to spin their cocoons in early April. I observed. this behavior on April 3, 2026.

 

  • Adults then emerge between Mid-April to early May. The flightiess females stay on their cocoon & release a sex pheromone to attract a mate. Males fly in a rapid, zig‑zag pattern when searching for pheromone plumes. After mating the females lay their eggs onto the cocoon and coat the eggs with a secretion. They then rub their own setae onto the secretion for a protective layer. The eggs are over wintering which means the eggs survive through winter & develop when temperature rises again.