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.
Why?
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.
EXCELLENT photography!
ReplyDeleteWhat an amazing photo of the owl butterfly laying eggs! Talk about being in the right place at the right time. (And, fortunately, the photographer could presumably remove the eggs right after the b'fly finished laying them.) Bravo for an interesting article and accompanying photos.
ReplyDeleteSo... why does the USDA not permit you to breed butterflies? Wouldn't that actually be "safer" than importing them? (Just curious.)
ReplyDeleteAnonymous, great question about raising our own pupae. For me, the main reason to raise butterflies from caterpillars would be to showcase the entire life cycle. It would not be cost effective in terms of labor or plant material, but certainly educational.
ReplyDeleteWe can submit additional permitting requests for rearing individual species of butterflies from eggs, but they would need to be reared in fully enclosed containers with fine mesh ventilation. So they would not be free to roam the butterfly house.
I think the reasoning for not allowing breeding in the exhibit is multi-fold. First, if butterflies were breeding successfully here, it would mean they had adapted to our seasons and hours of light, which are pretty different from those in their tropical habitat (though closer around the equinox). So butterflies reared here for multiple generations might make a quicker transition to natural Seattle daylight, should they happen to escape.
Butterflies are prone to parasitism and diseases (this is a whole article) which are of at least equal concern to the USDA as actual butterfly escapes. These are mostly problems for caterpillars and pupae. By rearing in a separate facility from the flight area, we could catch any such problems quickly. Again, however, this would be a step beyond what we are doing at this time.
Possibly a third concern is locomotion. Our exhibit is designed to prevent the escape of flying insects - adult butterflies. A caterpillar could conceivably crawl through spaces smaller than a butterfly could fly. I believe our structure would contain caterpillars effectively, but I might see things differently if I were in the shoes of an inspector.
In my opinion, another good reason for importing pupae is to provide an economic incentive for butterfly farming. I'd like to think that our commerce with these small businesses helps to preserve Lepediptera habitat -- but I may be dreaming.
ReplyDeleteYou'd think it would be okay to breed certain types of butterflys.
ReplyDeleteIt is a shame the caterpillars had to go, they are quite beautiful. However, good job in being vigilant!
ReplyDeleteThank you to the Pacific Science Center for bringing us responsible beauty and learning. While I would love to see a world filled with butterflies I do understand that to become those gorgeous creatures they must pass through the rather voracious lifecycle of a caterpillar. While we may moan a little over the USDA's rigid rules we can only wish they had been around before pigs, chickens and snakes decimated so many incredible bird populations in Hawaii or the yummy Zebra mussel that has clogged so many Great Lake waterways in turn killing off indigenous fish. The Pacific Science Center not only enlightens and informs us, they care for the long term repercussions of introduced exotics and the steps that must be taken to make sure they remain visitors. You have a dedicated Member in me.
ReplyDeleteWell spotted, Maida! Thanks for the article. Invasive species are a huge problem today, so I think it's great that PSC isn't just helping to prevent it, but educating the public about it.
ReplyDeleteAre you saying that you froze the caterpillers to death? If not what did you do with them?
ReplyDeleteDear Butterflybuckeroo,
ReplyDeleteUnfortunately, to comply with our permitting, larvae found in the butterfly house must be destroyed. Freezing is considered humane and quick for small, cold blooded animals. Having used soap sprays in my own garden in the past, I believe freezing is a better option when available.
But because none of us look forward to having to do it, we have a strong incentive to choose plants with a careful eye toward preventing egg laying.