An Exception to the Rules

 

wasp moth & Bidens alba

A polka-dotted wasp moth feeds on beggarstick flowers--Bidens alba.

The exceptional and beautiful polka-dotted wasp moth (Syntomeida epilais) breaks a number of Mother Nature’s rules:

 

#1. Adult moths fly at night. Fortunately for photographers, this beautiful moth flies in the daylight hours.

 

#2. Adult moths have pale or pastel colorations. With their iridescent gunmetal blue coloring punctuated by white dots and a bright red tip on their abdomens, these insects mimic wasps and display the warning coloration that tells birds that they are dangerous. As larvae (caterpillars) they consume poisonous foliage, so this is not an entirely false warning.

 

Polka-dotted wasp moths by Stibolt

Polka-dotted wasp moths attract each other by sounds

 

#3. Moths and butterflies emit pheromones (attracting scents) to attract mates. The female polka-dot wasp moth emits ultra sonic sounds to attract a mate, not the scented pheromones like most other moths and butterflies. When the male comes within a few feet he’ll start clicking as well. Some researchers have studied this habit in relation to bat populations. The theory is that decreasing bat populations make the sound emissions less dangerous.

 

#4 Moth larvae will only consume one species of plant. This is why as wildlife gardeners we plant a wide variety of native plants to serve as larval food sources for butterflies and moths. The polka-dotted wasp moth is native to south Florida and the Caribbean Islands and researchers think that it originally used the devil’s potato (Echites umbellatus), a member of the dogbane family (Apocynaceae) as its main host plant for the caterpillar. This family includes an interesting collection of poisonous-sap plants including milkweeds, frangipani, allamanda, deviltree, periwinkle, cape jasmine, and oleander.

The devil’s potato is relatively rare and its range is limited to southeast Florida. (Atlas of Florida Vascular Plants profile) These days the polka-dotted wasp larvae are sometimes found on other members of the dogbane family such as milkweeds, but mostly they have switched to oleander (Nerium oleander) as their main host plant and have increased their range with the plantings of this Mediterranean shrub. The Spanish brought oleanders to Florida in the 1600s and now, except for California, the polka-dot wasp moth is found wherever there are oleanders in the Americas. A group of these ravenous caterpillars can strip bare an entire shrub in a matter of a day or two. Now the other common name for this insect is the oleander moth and it has become a significant pest in the landscape.

Isn’t Mother Nature fun to study? Here one of her exceptional creatures has taken advantage of new plants introduced into its environment.

 

polka-dotted wasp moth on dog fennel

A polka-dotted wasp moth on dog fennel (Eupatorium capillifolium)

For more information see:
See my article on bidens and waspmoths No Need to Beg for Beggarticks for more resources.
Thanks to the reader of my last month’s post on poisons who asked about this insect that was being wrapped up by a garden spider.

 

© 2011, Ginny Stibolt. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us

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About Ginny Stibolt

Ginny Stibolt, a naturalist with a master's degree in botany, lives in Green Cove Springs in northern Florida.  She's written a book, Sustainable Gardening for Florida published by University Press of Florida.  Her website, Green Gardening Matters contains a six-year log of Florida gardening, nearly 100 articles, and links to more than 100 podcasts about gardening in Florida.  She's an active member of the Florida Native Plant Society and is one of the primary FNPS bloggers.  She is also an active member of the Lawn Reform Coalition.

Comments

  1. Donna says:

    Now that is one interesting insect…love the coloring…

    Reply
  2. Susan Wittig Albert says:

    Thanks, Ginny–a fascinating glimpse into a world that most of us never see!

    Reply
  3. Gaia Gardener says:

    Great post! Thanks for introducing me to an interesting and beautiful moth.

    Reply
  4. Carole says:

    Very interesting, I had assumed the wasp moth was exotic since the oleander is.

    Reply
  5. Ellen says:

    That coloration is incredible. If it had come home on my child’s coloring assignment, I would have thought it quite appropriate for an active imagination. Very cool and a good story too.
    Ellen recently posted..Ragweed, not Goldenrod, is the culprit!

    Reply
  6. Kevin Songer says:

    nice photographs with a great educational discussion. Thanks, Ginny!

    Reply
  7. Beatriz Moisset says:

    Nice photos of a beautiful moth. I don’t have the fortune to live in an area where it is present, but I have seen a similar one in Argentina.
    Another moth that has learned to take advantage of an introduced plant is the Ailanthus Webworm Moth, http://bugguide.net/node/view/430. As its common name suggests it feeds on Ailanthus or tree of heaven. It has expanded its range because of this introduced plant.
    Just like the polka-dotted wasp moth, it flies during the day and is brightly colored.
    Beatriz Moisset recently posted..Bees and vitamins

    Reply
  8. Athena Rayne Anderson says:

    Great post! I’d never heard of a moth that uses sound to advertise for sex!
    Most people don’t realize that moths are important pollinators too!
    Athena Rayne Anderson recently posted..New YouTube videos!

    Reply
  9. Steve Worden says:

    First sighting of the Moth, I thought it was a wasp. Found out that it was and its relationship to the orange caterpillars with the Punk Rocker hair styles on my oleander plants. Think both are strange but beautiful. HOWEVER, my oleander plants are taking a big hit. Don’t like destroying what mother nature has put here …. put would like to control the numbers of the creatures lunching here. Any good ideas…

    Reply
  10. Norma says:

    I have the same problem that Steve has. I found some eggs under my Desert Rose. I am assuming they belong to the Polk-A-Dot Wasp Moth I saw the other day on it. This moth is a beauty and I am positive it has to do with my Desert Rose having seed pods this year. I would hate to destroy these eggs but I don’t want to lose my plant. Please advise.

    Reply
  11. Ginny Stibolt says:

    Norma’s desert rose belongs to the dogbane family and so would also provide food for this caterpillar. If I wanted to preserve some of my landscape or specimen plants is to plant a few oleanders to sacrifice in an out-of-the-way corner and transfer the caterpillars to them from your favored plants. This is what I do for the black swallowtail caterpillars on my dill and parsley–I plant a row of parsley away from my other edibles to sacrfice. Who wouldn’t want to support those beautiful butterflies?

    Reply
  12. sara says:

    hey do pollka dot wasp moth sting

    Reply
    • Ginny Stibolt says:

      Sara, No they are moths. They look dangerous by design–they consume the poisonous oleanders, so they probably are poisonous to the birds as adults.

      Reply
  13. Beth says:

    Hi, Do they ever mutate to have red wings? We have enjoyed many cycles and recently had two solid red winged moths emerge along with the beautiful deep blue polka dotted moths. Thanks

    Reply
    • Ginny Stibolt says:

      Beth, I have no idea, but in nature anything is possible.

      Reply

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  1. My Polka-Dot Wasp Moth | Garden Almanac & Classroom Notes says:

    [...] them by releasing scent and it is active during the day not at night like most moths. (see An Exception to the Rules and Oleander [...]

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