Happy Moth Week! Crotalaria & Co-evolution

invasive pest plant, moth, Moth larval plant, Oslo Riverfront Conservation Area

Lots of people love only some Lepidoptera.  It’s the beautiful butterflies that get nearly all of the attention.  Moths, the other Lepidoptera, often get overlooked perhaps because most of them are creatures of the night and some of them are drab.  National Moth Week is July 21 through July 28 this year and highlights the beauty and ecological significance of moths.

Some moths are active during the day and rival butterflies in their beauty.  The ornate bella moth (Utetheisa ornatrix) is a poster child and is show above in a photo by University of Florida entomologist Dr. Don Hall.  All of the insect photos in this post are the handiwork of Dr. Hall.

This brightly colored and very variable moth has been studied extensively in part due to its ability to sequester toxins from its host plants, Crotalaria sp., sometimes collectively called rattleboxes.  Worldwide, there are more than 600 species of Crotalaria.  Florida is home to 15 species, 4 of which are native.  Fortunately, the ornate bella moth has co-evolved from feeding on the native species to feeding on exotic Crotalarias.

This moth lays its eggs only on Crotalaria foliage, and larvae (caterpillars) begin to feed on the leaves and “graduate” to feeding on the seeds, when possible.  Immature seeds contain about 5 times more of the toxic pyrrolizidine alkaloids than the leaves.  The larvae get better protection from predators, and we get invasive plant control.  Pupae sometimes can be found on the seed pods (a.k.a ratlleboxes).  Click here to learn about research at the Florida Museum of Natural History into this co-evolution.

Showy rattlebox, Crotalaria spectabilis, was introduced to Florida in 1914 as a cover crop, and has escaped from cultivation.  It frequently “appears” in disturbed areas at the Oslo Riverfront Conservation Area (ORCA) and is the most common species found at ORCA sometimes growing to be more than 8 feet tall …

Smooth rattlebox (Crotalaria pallida) also is found at ORCA, and my only (lousy) photo of an ornate bella moth is on this plant at the ORCA link, the much-disturbed former citrus grove on the south side of Oslo Road …

Look for this marvelous moth wherever you see rattleboxes.