Agreeable Tiger Moth

The agreeable tiger moth inhabits a wide range of open and semi-open habitats. It is most common in:

Old fields and meadows Roadsides and railway verges Forest edges and clearings Suburban gardens and parks Abandoned agricultural land Wetlands and marshes edges The species avoids dense, closed-canopy forest and extremely arid deserts, although it may occur in riparian corridors through otherwise unsuitable terrain. The key requirement for habitat suitability is the presence of herbaceous host plants for the larvae. In urban and suburban areas, the agreeable tiger moth is often one of the more commonly observed white moths at porch lights. It tolerates moderate levels of habitat disturbance and may benefit from the proliferation of weedy host plants in human-modified environments.

Many tiger moths, including species in the genus Spilosoma, possess tympanal organs on the thorax that allow them to detect the ultrasonic echolocation calls of bats, their primary nocturnal predators. When exposed to ultrasound, these moths may exhibit evasive flight manoeuvres, such as diving, spiralling, or dropping to the ground. Some arctiines also produce their own ultrasonic clicks in response to bat calls, which are thought to jam the bat's echolocation or to warn the bat of the moth's unpalatability. Whether S. congrua engages in such acoustic aposematism has not been studied, but it is plausible given that the behaviour is widespread in the subfamily.

The generic name Spilosoma is derived from the Greek words spilos (a spot, stain, or blemish) and soma (body), referring to the spotted abdomen characteristic of many members of the genus. The specific epithet congrua is Latin for "agreeable", "congruous", or "fitting". The precise reason for Walker's choice of this name is unknown. It may refer to the pleasing symmetry of the black spots on the white body, or it may simply have been an arbitrary choice from the vocabulary of descriptive Latin terms. The common name "agreeable tiger moth" directly translates the scientific name and was adopted by early 20th century American entomologists. The alternative name "New Hope tiger moth" derives from a later synonym, Spilosoma spesnova, where spes nova means "new hope" in Latin. This name was proposed by Smith in 1985 for what was thought to be a separate species, but was later synonymised.