Limacodidae or Euclidae is a family of moths in the superfamily Zygaenoidea or the Cossoidea (Scoble, 1992); the placement is in dispute. They are often called slug moths because their caterpillars bear a distant resemblance to slugs. They are also called cup moths because of the shape of their cocoons.
They are mostly tropical, but occur worldwide, with about 1000 described species and probably many more as yet undescribed species.
They are small, hairy moths, with reduced or absent mouthparts and fringed wings. They often perch
with their abdomens
sticking out at 90 degrees from the thorax
and wings. North American moths are
mostly cryptic browns, sometimes marked with white or green, but the hag moth
The final instar
constructs a silk cocoon
and hardens it with calcium oxalate excreted from the malpighian tubules. Cocoons have a circular escape hatch, formed from a line of weakness in the silk matrix. It is forced open by the pupa just prior to emergence of the adult (Epstein, 1996).
The larvae are typically very flattened, and instead of prolegs
they have suckers (Wagner, 2005). The thoracic legs are reduced, but always present and they locomote by rolling waves rather than walking with individual prolegs. They even use a lubricant
, a kind of liquified silk
, to locomote on (Epstein 1996).
Larvae might be confused with the similarly flattened larvae of Lycaenid butterflies,
but those caterpillars have prolegs, are always longer than they are wide, and are always densely
covered in short or long setae (hair-like bristles). The head is extended during feeding in the
Lycaenids, but remains covered in Limacodidae.
Many Limacodidae larvae are green and fairly smooth (e.g. Yellow shouldered slug, pictured), but others have tubercles with stinging hairs and may have bright warning colours. The sting can be quite potent (Marshall, 2006), causing severe pain.
The larval head is concealed under folds (Scoble, 1992). First instars skeletonize the leaf (avoiding small veins and eating mostly one surface), but later instars eat the whole leaf, usually from the underside (Wagner, 1995). Many species seem to feed on several genera of host plants (Scoble, 1992).
Research on Limacodidae larvae in temperate forests of eastern North America has found that they prefer glabrous leaves, presumably because the trichomes of pubescent leaves interfere with their movement (Lill et al. 2006).
are flattened and thin. They are highly transparent and the larva can be seen developing inside (Wagner, 2005). They may be laid singly or in clusters on leaves.
Limacodidae (e.g. Latoia viridissima, Parasa lepida, Penthocrates meyrick, Aarodia nana
) have caused serious defoliation
- Epstein, ME. 1996. Revision and phylogeny of the limacodid-group families, with evolutionary studies on slug caterpillars (Lepidoptera: Zygaenoidea). Smithsonian Contributions to Zoology, No. 582.
- Marshall, SA. 2006. Insects: Their natural history and diversity. Firefly Books.
- Scoble, MJ. 1992. The Lepidoptera: Form, Function and Diversity. Oxford University Press.
- Wagner, DL, 2005. Caterpillars of Eastern North America. Princeton University Press.
- Lill, JT, RJ Marquis, RE Forkner, J Le Corff, N Holmberg, and NA Barber. 2006. Leaf pubescent affects distribution and abundance of generalist slug caterpillars (Lepidoptera: Limacodidae). Environmental Entomology 35(3):797-806.
- Brisbane Limacodids, with photo of cocoon.
- Moths of Borneo