Butterfly hightlights for 2005 at Fermilab
Tom Peterson

November 17, 2005
With a 15 F temperature this morning and highs around freezing, I have to reluctantly admit that the butterfly season is over.  I saw a Purplish Copper last Friday, November 11, in the same location as the one photographed below, along Road C-West.  Orange Sulphurs and Cabbage Whites were also still out.  Incredibly, however, three or four species of living adult butterflies are still out here, hibernating in hidden cracks in trees, etc., awaiting the warm weather of spring.  These include the Mourning Cloaks and Eastern Commas (winter form), both of which may often be seen flying in the woods on warm March days.  They may even occasionally emerge during an unusually warm, sunny, January or February day.  Gray Commas should also be hibernating here, but I have only seen them at Fermilab in the summer.  Question Marks may also hibernate here; they are abundant here in the summer.  But like the Gray Commas, I have not found them flying on warm winter days.  Question Marks may also migrate to some extent, so without finding them in the winter, one cannot be sure that the summer generations have not moved up from further south.  These hibernators do not stay warm in the winter, they are cold-blooded, but their bodies produce a sort of "antifreeze" which prevents ice from forming in their bodies in the cold weather.  They cannot move to escape predators when so cold, but all these hibernating adult butterflies are well-camouflaged, with wings folded their undersides resembling bark or dead leaves.

It is still possible that one may see a butterfly this year.  Clouded Sulphurs and Orange Sulphurs seem to tolerate some freezing, I have occasionally seen them flying on a warm December day, but I do not think they survive the winter as adults.  So that's about it for the 2005 butterfly season in the Chicago area.  Perhaps in just three months, on some warm February day, a Mourning Cloak will give us an early start at butterfly watching in 2006.

November 8, 2005
Warm days and the lack of a series of really hard freezes have extended the butterfly season this year.  Incredibly, the photo below of the male Purplish Copper was taken today, November 8.  It is resting on a dead leaf of the wetland plant (a genus Polygonum species) on which the caterpillars feed.  This Purplish Copper was getting nectar from some of the last white asters still blooming. Orange Sulphurs and Cabbage Whites are also still flying.  These species both like to make use of the late-blooming dandelions.

September 19, 2005
Purplish Coppers and Bronze Coppers are among the late season butterflies again this year at Fermilab.  Last Friday I saw (photo below) a male Purplish Copper aggressively pursuing a female Bronze Copper.  The female always turned to face him as he walked and fluttered around, so the impression was that they were butting heads.  While the female seemed to understand right away that they were not compatible, the male did not seem to get it.  (No comment!)  It is delightful that these beautiful little butterflies help extend the summer season here at Fermilab.

Above, a male Purplish Copper pursues a female Bronze Copper.
 

August 1, 2005
Tigers!  No, not the cats, but the Tiger Swallowtails, seem particularly abundant this year.  These large, yellow butterflies may be seen soaring nearly everywhere on the Fermilab site.  They especially seem to like purple flowers like the Bee Balm in the prairie, thistle, Joe Pye Weed, and Butterfly Bush in our back yard.  Surprisingly, some female Tiger Swallowtails are black.  They are thought to mimic the Pipevine Swallowtail which is unpalatable to birds.  Giant Swallowtails and the smaller Black Swallowtails are also flying now.

July 11, 2005
The drought does not seem to have hurt the butterflies yet, in fact they like warm, dry weather.  But in the longer run, if the caterpillar food plants dry up, the impact of the drought on butterflies will be negative, like for us all.  Many of the tiny, brightly colored butterflies of the Gossamer-wing family (Lycaenidae) are flying on these hot July days, but with their small size and rapid flight, they are often hard to spot. Coral Hairstreaks  live in the open, brushy areas on the east side of the Fermilab site.  I find Banded Hairstreaks at the woods edges on the west side of Fermilab. Summer Azures favor brushy areas with dogwoods and other shrubs, while Eastern Tailed-Blues brighten up the the prairie trail and roadside edges, visiting clover and other flowers.

July 6, 2005
Many dark brown, almost black, medium-sized butterflies are presently flitting through the prairies and fields at Fermilab.  Up close one can see that they are not just plain black or dark brown, but have some eyespot markings.  These are Common Wood-Nymphs.   Their low, bouncing flight seems well suited to maneuvering through the prairie grasses.  Their caterpillars feed on grasses, and these butterflies have most certainly moved into our prairie restorations, where during the month of July they are probably the most common butterfly.

June 17, 2005
Along the edges of woods, such as on the eastern part of the Prairie Interpretive Trail off Pine Street, Great Spangled Fritillaries are now abundant.  These are large, orange butterflies, nearly the size of Monarchs, but with quite a different pattern of brown markings and silver spots on the underside.  A second generation of Meadow Fritillaries is now flying in the open fields with violets, such as in the tall grass just north of the Batavia Road entrance.  Meadow Fritillaries look like miniature Great Spangled Fritillaries when flying, but at rest one sees that the Meadow Fritillaries lack the silver spots on the undersides of the wings.

June 7, 2005
A mowed path straight north from the east guard shack at the Batavia Road entrance takes one along the woods/field edge where Little Wood-Satyrs and Spring Azures are abundant right now.  Little Wood-Satyrs are medium-sized brown butterflies with a low, bouncing flight characteristic of their subfamily, the Satyrinae.  Spring Azures are little, brilliant blue butterflies which unfortunately usually sit with wings closed, showing us only the whitish undersides at rest.

May 31, 2005
Bronze Coppers are now flying.  I saw four at noon today just south of the main ring. This is a butterfly which has declined in numbers in some parts of the US due to wetland destruction, but Bronze Coppers seem to thrive at Fermilab.  Some of the early summer skippers, Tawny-edged and Peck's, are also out now and may be seen visiting clover along the paths.

May 5, 2005
Warm weather again is bringing out the butterflies.   Meadow Fritillaries are flying in the open fields at Fermilab, and a few Tiger Swallowtails and Black Swallowtails have been seen here.  The common medium-sized yellow butterflies, Clouded Sulphurs, are out.

April 18, 2005
Spring Azures, small, bright, iridescent blue butterflies, are flying now.  They may be found around shrubs like dogwoods, on which the caterpillars feed.  Like those butterflies listed below, Spring Azures are among the first to appear in the spring.  Spring Azures typically sit with wings closed.  When they fly, one sees flashes of the bright, blue upperside.

April 12, 2005
With the warm weather of the past few weeks (up until today, anyway) butterflies have appeared.  Numerous Cabbage Whites are out, having emerged from over wintering chrysalises.  The hibernating butterflies, Mourning Cloak and Eastern Comma, were flying in the woods at Fermilab this past weekend.  Also, I have seen Painted Ladies and Red Admirals.  Painted Ladies do not survive the winter temperatures here, so they have had to fly up from the south already.  Red Admirals may also have traveled north, but many early Red Admirals are so very fresh looking, as this past weekend, that it seems that they could not have traveled very far.

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