He may look like a pretty butterfly, but this winged creature is actually a day-flying, evil-eradicating, heroic moth.
The Cinnabar Moth (Tyria jacobaeae) is a member of the Arctiidae (Tiger Moth) family — originally found only in Europe and western and central Asia — and is a relatively new resident to our area.
Initially introduced to Washington state in 1960, the Cinnabar Moth is part of a concerted effort to control the invasive poisonous plant — tansy ragwort — and all without the use of herbicides.
This is the time of year when you may see a Cinnabar Moth flitting through the wild grasses and plants in your neighborhood.
The Evils of Tansy Ragwort
Tansy ragwort (Senecio jacobaea) is a wild growing weed with a pretty yellow flower that can used as a source of yellow dye. But whatever mildly beneficial qualities the ragwort possesses, the good qualities are far outweighed by its poisonous nature:
“All plant parts are toxic, with the highest amount of alkaloids in flowers then leaves, roots and stems. Toxic properties are a possible threat to humans through food chain contaminants.” Source: Washington State Noxious Week Control Board
“Tansy ragwort is toxic, and can be lethal to cattle and horses … These toxic properties remain in cut plants found in hay. … Chronic, cumulative poisoning, and irreversible liver damage, including cirrhosis of the liver are the results of ragwort poisoning.” Source: Washington Department of Fish and Wildlife. 2006. South Puget Sound Wildlife Area Management Plan. Wildlife Management Program, Washington Department of Fish and Wildlife, Olympia. 67 pp.
Tansy ragwort flowers throughout the summer and grows on roadsides, in pastures, fields and cleared forested areas, at low and mid elevations. Ragwort contains many different alkaloids, making it poisonous to most creatures — but the Cinnabar Moth thrives on the invasive weed.
Both larvae and mature moths feed on tansy plants. The adult moths consume the nectar of the flowers, the larvae feast on the foliage and stems.
Meet the Hero
The larvae of the Cinnabar Moth can consume large amounts of the tansy ragwort alkaloids without a problem. In fact, the alkaloids are actually beneficial to the Cinnabar Moths, because as they absorb alkaloids, they also become a bitter bite in potential predators’ mouths.
The bright colors of both the larvae (yellow and black) and the moths (red and black) serve as universally readable warning signs of their foul taste.
Cinnabar Moth larvae also eat other plants in the Senencio plant family, including groundsels, dusty miller, and butterweeds, but the tansy ragwort is its favorite food.
Life Cycle of the Cinnabar Moth
Adults moths emerge in late spring from overwintering pupae.
The Cinnabar Moth is brightly colored, day-flying moth. Their crimson hindwings are bordered with dusky black and their dark grey forewings have a red streak towards the front margin and two red spots on the outer edges
The female moth lays her eggs under the leaves at the base of the ragwort plant. Larvae hatch in about two weeks.
Their development takes about one month, after this, they pupate on the ground and remain in diapause (physicologically enforced dormancy) until the following spring.
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Kimberly Mason is a freelance writer and photojournalist. She is the founder of The (Almost) Daily News website, enjoys using her Nikon to take pot shots at all things with wings and strives to learn something new every day. You can find her on Facebook, call her with questions or outdoors news tips at 360-269-5017, or email her at email@example.com.