Gardeners who grow Cannas (Canna sp.) are most likely familiar with their most common pest – the caterpillars of the Canna or Brazilian Skipper (Calpodes ethlius). These leaf-rolling larva do serious damage to the look of Canna foliage, although they rarely damage the plant so badly as to kill it.



Canna skippers lay their eggs individually on the broad leaves. The tiny larvae first eat their own eggshells, and then move on to the foliage itself.


Canna leaves are huge and don't give caterpillars much of a place to hide, so the caterpillars create their own shelters by cutting along the leaf in two places and then spinning silk threads from side to side. As the silk dries, it shrinks and pulls the leaf pieces together, creating a nice little hidy-hole for the caterpillar. The caterpillars nest in there during the day and emerge at night to feed. As they outgrow one nest, they create another. Canna skipper larvae grow quite large (2.5 inches or so), especially compared to their diminutive adult size.


Canna skipper caterpillars have an unusual characteristic – their bodies are transparent. The green you can see in the body of the caterpillar to the left is actually the leaf matter being digested in the caterpillar’s gut. The transparent body also makes it easy to see some other parts of the caterpillar’s anatomy, like the spiracles they use for breathing. (Click here to read more about caterpillar anatomy.)


Perhaps the most beautiful part of the canna skipper life cycle is the chrysalis. The light green chrysalis is speckled with black spots, and seems waxy and delicate, although it does wiggle when you touch it. Interestingly, the canna skipper chrysalis has a protruding tube where the butterfly’s proboscis forms (shown to the right in the photo below). This is a more common characteristic of moths in cocoon (sphinx moths also do this), and rarely seen in butterflies. In the picture below, the small tube pointing to the left contains the developing proboscis of the canna skipper butterfly within.

 
After the interesting stages of caterpillar and chrysalis, the canna skipper butterfly is somewhat dull in comparison. It’s a small brown skipper (about 2 inches) with some white marking on the wings. The proboscis is especially long, allowing these small butterflies to probe into deep flowers that other butterflies might not be able to manage.



If you grow Canna and find the caterpillars to be a pest, you can control them in several ways. Watch the leaves for eggs (they’re small and white) and scrape them off when you find them. Once the caterpillars appear, you can either pick them off and drop them in a bucket of soapy water, or spray them with insecticidal oil or a weak solution of dish soap and water. Be sure to coat the caterpillar directly and completely if you spray – the oils and soaps work by clogging the spiracles (breathing holes) of the caterpillars. If you don’t like the idea of killing the caterpillars, considering growing a canna or two in a patch by itself where you can move caterpillars when you find them on the rest of your canna.