Reprinted by Ion Exchange with permission. Forecast for Central Iowa August 1, 2008-August 15, 2008
Butterfly numbers and diversity are at their peak right now. Diversity will continue to be at a peak until about the middle of September. Numbers will remain high after that—possibly as late as the end of October depending on the weather. However, by that time the diversity will have crashed and only a few species will be represented.
Many of the butterflies you see at this time of the year are newly emerged, but some, particularly the larger butterflies, may be individuals who have lived for several weeks. If you have appropriate habitat you may see the same individual eastern tiger swallowtail or great spangled fritillary over several days. Butterflies can become quite raggedy over a period of time, but can still survive.
There can be some unexpected butterfly watching opportunities at this time of year. A few years back I went on a ride on the Boone and Scenic Valley Railroad (Boone, Iowa). The ride goes for several miles, and there are wooded stretches and areas with some prairie plants. I got great looks at lots of butterflies, especially eastern tiger swallowtails and giant swallowtails. The northwestern part of the route, near Fraser and Holst State Forest had very large populations of giant swallowtails.
Rides on bike paths can be quite good as well. You might need to keep the ID books at home and just concentrate on the ride, however.
If you happen to pass a hay field you might see clouds of butterflies—clouded and orange sulfurs in numbers much greater than you will see elsewhere. Puddles near a hay field may yield hundreds of these butterflies which all fly up at the same time.
Watch the white butterflies at this time of year. Cabbage whites are common, as are white forms of clouded and orange sulfurs. If you look closely, you can tell them apart quite easily—the forewings of cabbage whites coming to a point instead of being rounded, and lacking the black border. You may see a white butterfly that is clearly different from either—one that is very white with no border, but which has more dark spots on it than the cabbage white. That will be the checkered white, which is a migrant that comes in to the state late in the summer.
In normal years we would be seeing great numbers of little yellows about now. However, I have not seen any yet this year. There have been huge numbers of summer azures, however—many more than normal, and flying about 3 weeks after one would expect their peak.
The American snout is a distinctive butterfly with a long nose. It can form huge swarms in Texas, where certain forms of hackberry tree are found.
In Iowa it is found in smaller numbers. I usually see only a few individuals each year.
Cloudless sulfurs can sometimes be seen late in the summer. Once again, they are quite common in the south but not so common in Iowa. Cloudless sulfurs resemble the more common clouded and orange sulfurs but are quite a bit larger. Look for fiery skippers to be fairly numerous as well.
Some species are found here pretty much all summer but reach fairly high numbers late in the year. They include before mentioned clouded and orange sulfurs, eastern tailed-blues, pearly crescents, and silvery checkerspots.
Black swallowtails, painted ladies, red admirals and monarchs may be found in fairly high numbers in prairie and old-field areas, and hackberry and tawny emperors can be found in the woodlands.
Summer is flying by (in more ways than one). Make the time to enjoy the show.
Harlan Ratcliff
References:
Schlicht, Dennis, John C. Downey, and Jeffrey C. Nekola. 2007. The Butterflies of Iowa. The University of Iowa Press, Iowa City, IA.
Scott, James A. 1986. The Butterflies of North America. A Natural History and Field Guide. Stanford University Press, Stanford CA.
IA-BTRFLY: The Iowa Butterfly and Dragonfly list serve.
http://www.wisconsinbutterflies.org/ sightings page.
http://www.naba.org/ sightings page.
Ratcliff, Harlan: 2003-2007 Unpublished butterfly survey results.
Many of the butterflies you see at this time of the year are newly emerged, but some, particularly the larger butterflies, may be individuals who have lived for several weeks. If you have appropriate habitat you may see the same individual eastern tiger swallowtail or great spangled fritillary over several days. Butterflies can become quite raggedy over a period of time, but can still survive.
There can be some unexpected butterfly watching opportunities at this time of year. A few years back I went on a ride on the Boone and Scenic Valley Railroad (Boone, Iowa). The ride goes for several miles, and there are wooded stretches and areas with some prairie plants. I got great looks at lots of butterflies, especially eastern tiger swallowtails and giant swallowtails. The northwestern part of the route, near Fraser and Holst State Forest had very large populations of giant swallowtails.
Rides on bike paths can be quite good as well. You might need to keep the ID books at home and just concentrate on the ride, however.
If you happen to pass a hay field you might see clouds of butterflies—clouded and orange sulfurs in numbers much greater than you will see elsewhere. Puddles near a hay field may yield hundreds of these butterflies which all fly up at the same time.
Watch the white butterflies at this time of year. Cabbage whites are common, as are white forms of clouded and orange sulfurs. If you look closely, you can tell them apart quite easily—the forewings of cabbage whites coming to a point instead of being rounded, and lacking the black border. You may see a white butterfly that is clearly different from either—one that is very white with no border, but which has more dark spots on it than the cabbage white. That will be the checkered white, which is a migrant that comes in to the state late in the summer.
In normal years we would be seeing great numbers of little yellows about now. However, I have not seen any yet this year. There have been huge numbers of summer azures, however—many more than normal, and flying about 3 weeks after one would expect their peak.
The American snout is a distinctive butterfly with a long nose. It can form huge swarms in Texas, where certain forms of hackberry tree are found.
In Iowa it is found in smaller numbers. I usually see only a few individuals each year.
Cloudless sulfurs can sometimes be seen late in the summer. Once again, they are quite common in the south but not so common in Iowa. Cloudless sulfurs resemble the more common clouded and orange sulfurs but are quite a bit larger. Look for fiery skippers to be fairly numerous as well.
Some species are found here pretty much all summer but reach fairly high numbers late in the year. They include before mentioned clouded and orange sulfurs, eastern tailed-blues, pearly crescents, and silvery checkerspots.
Black swallowtails, painted ladies, red admirals and monarchs may be found in fairly high numbers in prairie and old-field areas, and hackberry and tawny emperors can be found in the woodlands.
Summer is flying by (in more ways than one). Make the time to enjoy the show.
Harlan Ratcliff
References:
Schlicht, Dennis, John C. Downey, and Jeffrey C. Nekola. 2007. The Butterflies of Iowa. The University of Iowa Press, Iowa City, IA.
Scott, James A. 1986. The Butterflies of North America. A Natural History and Field Guide. Stanford University Press, Stanford CA.
IA-BTRFLY: The Iowa Butterfly and Dragonfly list serve.
http://www.wisconsinbutterflies.org/ sightings page.
http://www.naba.org/ sightings page.
Ratcliff, Harlan: 2003-2007 Unpublished butterfly survey results.
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