Other Common Names
Defoliating Hemlock Moth (name used in the weed control industry)
Synonyms and other taxonomic changes
the species epithet is commonly spelled (in Europe) with a single "e" - alstromeriana
Adult: forewing creamy or pale brown with whitish area at base and a large dark squarish blotch that touches the costa mid-way along the wing; a short broken dark line runs obliquely just above the blotch; a few dark spots usually present along the wing fringe, and several small dots may be scattered across the wing.
Larva: changes color and markings as it matures, from clear whitish-yellow (early instars) to black-dotted greenish (late instars). See detailed description
by Ian Smith.
northeastern US and southeastern Canada, plus northwestern US and southwestern Canada; spreading inland from both regions
native to Europe
fields, roadsides, waste places - wherever the host plant (Poison Hemlock) occurs; adults attracted to artificial light
adults fly from April to August
larvae from May to July
larvae feed only on Poison Hemlock (Conium maculatum), which was introduced to North America from Europe in the 1800s
First recorded in North America in New York State in 1973; accidentally introduced to the US northwest shortly after, and has since spread rapidly from both locations.
Larvae of this species are commercially available for biological control of Poison Hemlock.
The common name of Poison Hemlock Moth is preferable to Hemlock Moth or Defoliating Hemlock Moth because this species feeds solely on the herbaceous plant Poison Hemlock (Conium maculatum), and has no association with the coniferous trees called Hemlock (Tsuga spp.).
live adult image
(Ian Kimber), and description of larval stages (Ian Smith, UK Moths)
live adult image
and eggs on host plant (Eric Coombs, Oregon Dept. Agriculture)
pinned adult image
(B. Gustafsson, Sweden)
live larva images
(Ian Smith, UK Moths)
live larva image
on flowers of host plant (Steve Nash, UK Moths)
image of feeding damage
caused by larvae (Eva Castells, U. of Illinois)