Written by Pam Otto
Wednesday, 30 October 2013 00:00
Favorable conditions this year may mean increased numbers in '14
Where have all the butterflies gone?”
It’s a question that seemingly was on everyone’s minds this summer, at least the minds of everyone who loves butterflies. And really, who doesn’t?
With delicate wings covered in colorful scales, and mouthparts that sip nectar instead of, say, human blood, butterflies typically rank high on people’s lists of “Likes” in nature. In fact, we naturalists have a saying, “Butterflies are easy,” meaning that it’s not hard to get people to appreciate them. Ticks and mosquitoes, by contrast, are hard, but that’s another story for another time.
Back to butterflies. Any population of living organisms is prone to fluctuations over time. When conditions are favorable, numbers go up; when times are tough, numbers go down.
Last year, you may recall, was undeniably tough. Spring arrived in, what, February, which may at first have seemed like a blessing, but was then followed by months of drought and extreme heat. Many plants that are vital to caterpillar survival wilted, then shriveled, leaving little for the youngsters to munch on.
Those larvae that made it to butterfly-hood found that being a grownup wasn’t all wine and roses either. Puddling, a behavior many adult butterflies practice as a means of gathering nutrients from moist soil, was almost nonexistent, save for those lucky enough to be near a shrunken river or stream.
Finding nectar, another key component of butterfly diets, was equally challenging. Produced as a sweet enticement for pollinators, nectar is an “extra” that plants in strict survival mode can do without. They did, but then so did the butterflies.
Things were even tougher for monarchs. Poorly provisioned, they nonetheless had to make a 1,700-mile migration flight to their wintering grounds in the mountain ranges of central Mexico. Researchers estimate the population that overwintered from 2012 to 2013 numbered 60 million, which is a steep drop from the species’ 350 million average.
Okay, enough of this gloom and doom. I may be in the minority but, even so, I have a hunch that butterfly numbers will come back again. Just as our weather patterns did them a disservice last year, it may give them a boost next year. We’ll just have to wait and see.
In the meantime, we have sphinx moths.
I’ve lost track of the number of calls, emails and text messages I’ve received over the past month or so reporting “this thing that looks like a hummingbird” hovering in front of flowers throughout the area.
The most commonly reported species is the white-lined sphinx, Hyles lineata, although there have been a fair number of clearwing moths (Hemaris spp., which people frequently describe as “small hummingbirds”, or “large bumblebees”) and assorted others too.
Although these moths superficially resemble butterflies, and belong to the same insect order, Lepidoptera, their life cycles feature some significant differences.
For one, while most nonmigratory butterfly species overwinter above ground, typically as eggs or as pupae in chrysalises, the sphinx moths by and large overwinter below, in pupal chambers dug in soil.
Interestingly, white-lined sphinx moths are prone to population explosions in warmer, drier climates like those in the Southwest—and here, last year. Maybe, just maybe, there’s a connection between 2012’s weather patterns and 2013’s apparent sphinx moth success.
This past summer was marked by early rains and, for the most part, seasonable temperatures from start to finish.
It will be interesting to see how our weather this year affects next year’s moth—and butterfly—numbers. I’ve made a note on my calendar to take a look at this topic again in September of 2014. We’ll revisit it then, if not before…
Pam Otto is the Manager of Natural Programs and Interpretive Services for the St. Charles Park District
Last Updated on Tuesday, 29 October 2013 13:24