Notice anything missing in the Tropical Butterfly House? If you answered, “The umbrella plant is gone,” you must be visiting us a lot! Give yourself a pat on the back! This week our Horticulture staff removed that tall, willowy sedge plant, Cyperus alternifolius that loomed over the south goldfish pond.
During routine plant grooming on March 16th, horticulturist Maida Ingalls noticed several caterpillars of different instars on the fronds of the umbrella plant. These odd looking creatures were easily recognizable as the caterpillars of Owl butterflies, Caligo memnon.
Unfortunately, this wasn’t the first infestation of Caligo caterpillars. Several years ago some had been found on the same umbrella plants. Those larvae were removed and destroyed. The Tropical Butterfly House is a controlled environment with strict USDA permitting requirements that forbid us from growing caterpillars on our premises. Because of our permit restrictions, we have been carefully watching this plant and others for signs of butterfly larvae.
After a short consultation, Maida and Horticulture Supervisor Jeff Leonard cut down and removed all of the umbrella plant foliage and stalks, placing it in the freezer for a minimum of 72 hours. Next, they will completely dig up the plants’ roots with hopes that some day they can install a waterfall that will run into the pond below.
Maida reminds us, “Caterpillars are masters of camouflage. It’s hard for the casual observer to see them on a plant because they easily blend in with the stems and mimic the veins of the leaves.”
Even though we select only plants that will not stimulate the butterflies to lay eggs, it’s not unusual for Science Interpreters or Life Sciences staff to come across tiny Lepidoptera eggs every now and then. As Life Sciences manager Sarah Moore explains:
“The pressure on female butterflies to lay their eggs is pretty strong. They pick up on scents, and on visual cues; color, texture, and reflectivity of objects can all trigger egg laying. We’ve had the most problems with Caligos. Besides plant foliage, we’ve found them laying eggs on guests’ clothing, walls, glass and once, a butterfly laid eggs on my plastic eyeglass frames!”
The Life Sciences staff is ever vigilant, looking for the tell-tale signs of chewed foliage and caterpillar frass among the plantings. The continual monitoring of our garden to allow only butterflies – not their offspring – keeps us in compliance with the USDA permitting requirements and makes a more pleasant environment for all.