''Euchaetes egle'', the milkweed tiger moth or milkweed tussock moth, is a moth in the family

Erebidae The Erebidae are a family of moths in the superfamily Noctuoidea. The family is among the largest families of moths by species count and contains a wide variety of well-known macromoth groups. The family includes the underwings ('' Catocala'') ...

and the tribe

Arctiini __NOTOC__ The Arctiini are a tribe of tiger moths in the family Erebidae. Systematics The tribe was previously treated as a higher-level taxon, the subfamily Arctiinae, within the lichen and tiger moth family, Arctiidae. The ranks of the fami ...

, the tiger moths. The species was first described by

Dru Drury Dru Drury (4 February 1724 – 15 December 1803) was a British collector of natural history specimens and an entomologist. He had specimens collected from across the world through a network of ship's officers and collectors including Henry Sme ...

in 1773. It is a common mid- through late summer feeder on

milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to humans ...

s and

dogbane Dogbane, dog-bane, dog's bane, and other variations, some of them regional and some transient, are names for certain plants that are reputed to kill or repel dogs; "bane" originally meant "slayer", and was later applied to plants to indicate tha ...

. Like most species in this family, it has chemical defenses it acquires from its host plants, in this case,

cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for c ...

s. These are retained in adults and deter bats, and presumably other predators, from feeding on them.Hristov, N. L. & Conner, W. E. (2005). "Effectiveness of tiger moth (Lepidoptera, Arctiidae) chemical defenses against an insectivorous bat (''Eptesicus fuscus'')". ''Chemoecology''. 15 (2): 105–113. Only very high cardiac glycoside concentrations deterred bats, however. Adults indicate their unpalatability to bats with ultrasonic clicks from their tymbal organs.

Range

It is found from southern Canada and south through Texas and Florida in North America.*Wagner, D. L. (2005). ''Caterpillars of Eastern North America''. Princeton University Press.

Lifecycle

One generation per year occurs in the north, and two or more may occur in the south.

Egg

Females lay eggs in masses on the undersides of leaves.

Larva

Early

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...

s appear slightly hairy and gray. They skeletonize whole leaves gregariously, leaving lacy leaf remnants. They are gregarious until their third instar. Later instars sport tufts of black, white and orange (sometimes yellow) setae (hairs). The head capsule is black. The later instars wander much more, and may appear alone or in groups of up to 10. Mature caterpillars occur from June onwards. Larvae grow as long as 35 mm. Image:Euchaetes2.JPG, Early instar Image:Euchaetes.JPG, Late instar Image:Euch attack.JPG, Under attack of a pentatomid Euchaetes egle pupa

Pupa

The gray cocoon is felted, with hairs from the larvae, and overwinters (Wagner, 2005).

Adults

Wings are grayish. Abdomens are hairy and yellow, each with a row of black dots on its dorsum. Males use their tymbal organs in calling females and in defense against bats.

Food plants

This moth frequently uses milkweeds (''Asclepias'' spp.) and sometimes dogbane (''Apocynum'' spp.) as larval host plants. Larvae often feed on older milkweed shoots, and seldom share shoots with monarchs (''

Danaus plexippus The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. I ...

''), which prefer younger ones. Dogbanes and milkweeds produce a sticky latex that can impede larval feeding. Early instars avoid the veins by skeletonizing the leaves. Older larvae sever the veins that supply the latex, which reduces latex flow to the area on which they feed.Dussourd, D. E. & Denno, R. F. (1991). "Deactivation of plant defense: Correspondence between insect behavior and secretory canal architecture". ''Ecology''. 72 (4): 1383–1396.

References

External links

* Range map
''Moths of Maryland''
Images of adult {{Taxonbar, from=Q1764213 Moths described in 1773 Phaegopterina Moths of North America Taxa named by Carl Linnaeus