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If
it seems there are fewer butterflies in your yard this summer, the
culprit could be the local shopping mall or that new subdivision down
the street, or even your neighbor's rose garden. Butterflies are delicate, territorial creatures that don't
like changes in their environment, says John Watts, curator of the
Butterfly Pavilion in Westminster. Watts says Colorado is home to more
than 250 butterfly species - only Texas, California, Arizona and
Florida have more - but "the numbers are decreasing somewhat." Blame it on the destruction of the winged ones' natural
habitat, whether it's a grassy prairie in Parker or an alpine valley in
Vail. "If you have a beautiful meadow and you put in a shopping
center parking lot, people think, 'Well, the butterflies will just fly
somewhere else,"' says Jeffrey Glassberg, president of the North
American Butterfly Association in Morristown, N.J. "That's 100 percent
not true. Those butterflies are gone forever." The problem, says Glassberg, is that most butterflies are
small and can't fly very far. And even if they did manage to find a
similar natural habitat nearby, it would already be supporting its own
population of butterflies. Even if the shopping center or home developer landscapes the
denuded meadow, unless it's planted with native grasses, flowers, trees
and bushes, it might as well be butterfly hemlock, Glassberg says. "As far as a butterfly is concerned, a yardful of stuff like
roses and rhododendrons might as well be a movie set - it looks good to
the eye, but it's all fake." Still, despite all the development along the Front Range, the
metropolitan area is home to 50-100 butterfly species, Watts says.
Glassberg says Gilpin County holds the nation's record for most
butterfly species counted on one day - 104. A hundred or so more
species live in the mountains. "There are butterflies at every elevation in the state," says
Watts. "They're pretty forgiving insects, as long as we give them
conditions they can tolerate." Those conditions include plenty of sunlight, because
butterflies' wings function as tiny solar panels. "A butterfly's body
has to be a certain temperature before it can fly," Watts says. Natural predators, such as spiders and particularly the
European paper wasp, also cause butterfly numbers to dwindle, says
Whitney Crenshaw, an entomology professor at Colorado State University.
These wasps migrated to the state five years ago and now infest
backyards along the Front Range. One of their favorite foods is
caterpillars, Crenshaw says. The wasps, which look like yellow jackets,
build open, paperlike hives and mature in mid-July. Wasp traps don't work on these papery predators, Crenshaw
says. "You have to knock down their hives. Do it at night. I knock them
down all the time, and I haven't been stung yet." Or you can try wasp spray, but avoid pesticides and insecticides, which kill caterpillars and butterflies.
"Butterflies
are wonderful environmental indicators - if you destroy their habitat,
they disappear," Watts says. "They're not just pretty creatures. They
serve
Aflutter with facts
Butterflies are sensitive to
environmental conditions, so their populations may vary from year to
year depending on the weather. CSU's Whitney Crenshaw says he has seen
more painted ladies this year because of rainy conditions in the
southern United States, but the rainy spring in Colorado resulted in
the lowest miller moth population in two decades. Most butterflies live only three weeks to a month, but some breed a few times a year.
That's
why you might see a lot of butterflies in June, fewer in July, more in
August and so on. The butterfly season in Colorado is generally May to
October. Mountain butterflies are smaller and darker than Front Range
butterflies to help them absorb heat. They hang out on the south sides
of peaks, along creeks and in meadows, avoid dark forests. In the
highest tundra, where summers are short, it could take two years for a
caterpillar to become a butterfly. To identify butterflies indigenous to Colorado, visit npwrc.usgs.gov/resource/distr/epid/bflyusa/bflyusa.htm.
Source: John Watts, Jeffrey Glassberg and Whitney Crenshaw
Mutual attraction
Even if your backyard is never
going to be mistaken for a native meadow, it can still attract
butterflies. Watts says an average-size yard could be home to half a
dozen butterfly species. Make sure there's a sunny area, with shelter
from the wind, and fences shorter than 10 feet. "The butterflies in
Colorado evolved where there were no tall trees, so they're used to
flying around, not over, obstacles," Watts says. Then plant native
species or caterpillar and butterfly-attracting non-natives. These
include: TREES
Ash, cottonwood, aspen, poplar, willow, elm
GRASSES, BUSHES AND WEEDY PLANTS
Alfalfa, clover, milkweed (monarchs' favorite), butterfly bush, ornamental thistle, rabbitbrush, flax
FLOWERS
Aster,
bee balm, cosmos, gaillardia, lilac, marigold, sweet pea, zinnia,
verbena, blazing star, coneflower, sunflower, hollyhock, penstemon,
Indian paintbrush, native wildflower seeds HERBS AND VEGETABLES
Mint, dill, parsley, fennel, carrots
For information on butterfly plants, check out ext.colostate.edu/PUBS/INSECT/05504.html.
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