The owlet moths (family Noctuidae) account for over 25% of all butterflies and moths. As you might expect in a family this large, there's a good deal of diversity within this group. Though there are exceptions, most noctuids share a common set of traits outlined here. The family name, Noctuidae, derives from the Latin noctua meaning little owl or night owl (which in turn derives from nox, meaning night).
As you've undoubtedly already deduced from the family name, owlet moths tend to be nocturnal. If you've ever tried black lighting for insects, you must have collected some noctuids, because most will readily come to lights.
The owlet moths are robust, stout-bodied insects, usually with filiform antennae. The fore wings tend to be mottled in color, often cryptic, and slightly longer and more narrowed than the hind wings. In most, the hind wings will be brightly colored, but kept hidden under the forewings when at rest. Some owlet moths have tufts on the dorsal surface of the thorax (in other words, they're furry!).
For those readers who enjoy confirming their ID's by studying wing venation details, you should note the following traits in the owlet moths you collect:
- The subcosta (Sc) arises near the base of the hind wing.
- The subcosta (Sc) fuses briefly with the radius near the discal cell in the hindwing
- Three medio-cubital veins extend to the distal edge of the hind wing
As David L. Wagner notes in Caterpillars of Eastern North America, there are no unique identifying traits of caterpillars in this family. In general, noctuid larvae are dull in color, with smooth cuticles and five pairs of prolegs. Owlet moth caterpillars go by varied common names, including loopers, earworms, armyworms, and cutworms.
Owlet moths sometimes go by other common names, such as underwing moths or cutworm moths. The family is divided into several subfamilies, although there is some disagreement about their classification, and some sources may consider these groups separate families entirely. I generally follow the classification system found in the latest edition of Borror and Delong's Introduction to the Study of Insects.
Noctuid caterpillars vary greatly in their diets, depending on the species. Some feed on foliage, living or fallen, some on detritus or decaying organic matter, and still others feed on fungus or lichens. Some noctuids are leaf miners, and others stem borers. The family Noctuidae includes some significant pests of agricultural crops and turfgrass.
Adult owlet moths usually feed on nectar or honeydew. Some are capable of piercing fruit, thanks to a sturdy, sharp proboscis. One very unusual noctuid moth (Calyptra eustrigata feeds on the blood of mammals. You only need to worry about these blood-suckings moths if you live in Sri Lanka or Malaysia, fortunately.
Noctuid moths undergo a complete metamorphosis, just like any other butterflies or moths. Most owlet moth caterpillars pupate in the soil or leaf litter.
Special Adaptations and Behaviors:
The nocturnal noctuids can detect and avoid hungry bats, thanks to a pair of tympanal organs located at the base of the metathorax. These auditory organs can detect frequencies from 3-100 kHz, enabling them to hear a pursuing bat's sonar and take evasive action.
Range and Distribution:
Globally, the noctuids number well over 35,000 species, with the worldwide distribution you would expect within such a large group. In North America alone, there are approximately 3,000 known species of owlet moths.
- Borror and DeLong's Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson
- Caterpillars of Eastern North America, by David L. Wagner
- Kaufman Field Guide to Insects of North America, by Eric R. Eaton and Kenn Kaufman
- Family Noctuidae, North Dakota State University. Accessed January 14, 2013.
- Family Noctuidae, Butterflies and Moths of North America website. Accessed January 14, 2013.
- Family Noctuidae, by Dr. John Meyer, North Carolina State University. Accessed January 14, 2013.