Arctiinae

Leach, 1815

Tiger Moths and Allies, Tiger Moths, Woolly Bear Moths, Footmen, Lichen Moths, Wasp Moths

Tribe Guides

Arctiini(Tiger Moths)
Lithosiini(Lichen Moths)

Arctiinae is a large and diverse of within the Erebidae, comprising approximately 11,000 worldwide. The subfamily includes tiger moths, footmen, lichen moths, and moths. Many species are characterized by aposematic coloration, chemical defenses, and the production of ultrasonic sounds for defense and communication. The group was formerly classified as the family but was reclassified as a subfamily of Erebidae based on phylogenetic studies.

Apantesis obliterata by (c) Doug Macaulay, some rights reserved (CC BY), uploaded by Doug Macaulay. Used under a CC-BY license.

Lycomorpha by (c) gailhampshire, some rights reserved (CC BY). Used under a CC-BY license.

Lycomorpha regulus by (c) Toby, some rights reserved (CC BY), uploaded by Toby. Used under a CC-BY license.

Pronunciation

How to pronounce Arctiinae: /ɑrkˈtaɪ.iːˌni/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

The most definitive diagnostic feature is the presence of a tymbal organ on the —membranous structures that can be vibrated to produce ultrasonic sounds. Additional distinguishing characters include: thoracic tympanal organs with distinctive location and structure; particular arrangements of larval setae; distinctive wing venation; paired glands near the ovipositor in females; and anal glands in females. The combination of these traits separates Arctiinae from similar within Erebidae.

Images

Habitat

Occurs in virtually all terrestrial from Arctic tundra to tropical rainforests. occupy forests, grasslands, meadows, wetlands, and urban areas. Larval habitats depend on plant availability; many species are associated with specific plant . Some temperate and Arctic species overwinter as larvae in exposed conditions, including on snow surfaces.

Distribution

distribution with highest diversity in tropical regions, particularly the Neotropics (approximately 6,000 ). Present on all continents except Antarctica. Well-represented in North America, Eurasia, Africa, Asia, Australia, and Pacific islands.

Seasonality

Most are and active year-round in tropical regions. Temperate and Arctic species typically have periods during warmer months, with larvae . Some species are , particularly -mimicking forms and certain tiger moths. At least one species, Borearctia menetriesii, is not attracted to light.

Diet

Larvae are predominantly herbivorous, with many being . Some species are monophagous or oligophagous, feeding on specific plant . primarily feed on nectar, with some species also acquiring defensive compounds by regurgitating and consuming decomposing plant material containing or cardiac glycosides.

Host Associations

flowering plants - larval food sourcewide range of herbaceous and woody plants; many
milkweeds (Apocynaceae) - larval food source and chemical defense acquisition such as Euchaetes egle sequester cardiac glycosides
plants containing pyrrolizidine alkaloids - chemical defense acquisition acquire and transfer defensive compounds to
Senecio and related Asteraceae - larval food sourceTyria jacobaeae (cinnabar moth) is monophagous on ragworts

Life Cycle

Holometabolous development with complete . are laid on or near plants. Larvae pass through multiple instars, with some temperate as larvae and producing cryoprotectant chemicals to survive freezing. occurs in silk cocoons, often incorporating larval hairs. Some Arctic and temperate species overwinter in the larval stage and complete development the following spring.

Behavior

produce ultrasonic clicks using tymbal organs for defense against bat and for mating communication. Some can jam bat echolocation. When disturbed, woolly bear caterpillars roll into a tight spiral or drop from perches suspended by silk. Larvae commonly bask to accelerate digestion. Social ranges from solitary to gregarious. Males evert androconial glands (coremata) during courtship to disperse demonstrating based on accumulated toxins.

Ecological Role

Herbivores that transfer plant secondary compounds through . Important prey for bats, birds, and other . Chemical makes many unpalatable, contributing to aposematic defense systems. serve as . Some species are significant defoliators, with the fall webworm (Hyphantria cunea) being a notable pest of ornamental and crop trees.

Human Relevance

Fall webworm is an economically significant pest of shade trees and crops. Some are used as agents, such as the cinnabar moth for ragwort control. Woolly bear caterpillars feature in North American folklore as weather predictors, spawning festivals in Ohio, Kentucky, and North Carolina. are frequently encountered at lights and are popular subjects for natural history observation and photography. Historically, some species were used for silk production.

Similar Taxa

LymantriinaeSome Arctiinae larvae were historically misidentified as tussock moths due to hairy appearance, but Arctiinae lack the distinctive tussock larval characteristics and possess the diagnostic tymbal organ.
Sesiidae (clearwing moths)Both include -mimicking with clear wings, but Sesiidae lack tymbal organs and have different wing venation; have wasp-like appearance with narrow bodies and often possess transparent wings.
ZygaenidaeSome zygaenid are mimics with similar aposematic coloration, but they lack the tymbal organ and have different larval .
Herminiinae (litter moths)Phylogenetically closely related within Erebidae, but Herminiinae lack tymbal organs and typically have drab coloration with different wing venation.

Misconceptions

The 'tussock ' has been incorrectly applied to some Arctiinae based on larval hairiness; true tussock moths belong to Lymantriinae. Folklore suggesting that woolly bear caterpillar banding predicts winter severity is biologically unfounded; band width varies with instar, not weather. The name 'sheep moth' (Hemileuca eglanterina) does not indicate any association with sheep; larvae feed exclusively on plants.

More Details

Ultrasonic communication and defense

The tymbal organ is unique to Arctiinae within Erebidae and represents a major evolutionary innovation. Sounds serve dual functions: aposematic signaling to bats (advertising unpalatability) and active jamming of bat echolocation in some . This acoustic defense system is among the best-studied examples of -prey in insects.

Chemical defense sequestration

Arctiinae exhibit sophisticated mechanisms for acquiring, storing, and transferring defensive compounds. Larvae sequester cardiac glycosides, , and other compounds from plants. can acquire additional compounds through pharmacophagy—consuming decomposing plant material. Males transfer these compounds to females during mating, and females transfer them to , providing multi-generational defense.

Taxonomic reclassification

Molecular phylogenetic studies demonstrated that the former was nested within Erebidae, most closely related to Herminiinae and Aganainae. To preserve monophyly, Arctiidae was reduced to rank as Arctiinae, with former subfamilies becoming tribes (Arctiini, Lithosiini, Syntomini) and former tribes becoming subtribes.

Crystal scales discovery

Recent research has identified novel 'crystal ' or 'crystal macrosetae' in male Arctiinae associated with androconial organs. These scales appear to be developmentally arrested, consisting of thin envelopes filled with viscous sugar-like material that crystallizes after death. Found in over 80 across multiple subtribes, these structures represent an uncharacterized communication or defense system.