HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
The Poweshiek Skipper Project
 
Butterfly Forecasts for Central Iowa  
  June 2021  
  Joel Asaph Allen was a zoologist and ornithologist who was a curator of birds and mammals at the American Museum of Natural History.  In that capacity, he would often take field trips to such exotic locations as Brazil, Florida, and the great plains.  gray copperOn one of those trips, in June of 1869, he visited Denison and New Jefferson, Iowa.  In addition to collecting birds and mammals he collected some butterfly specimens which he gave to Samuel Hubbard Scudder, one of the leading entomologists at the time.  Mr. Scudder published a description of the species as Chrysophanus dione.   It turned out to be a new species, discovered in the young state of Iowa.
Gray coppers seem to like prairie or old field habitats.  If you see one there are likely to be a lot more around when you look for them.  They are very visible, being large for gossamer-winged butterflies.  In Iowa, they have one generation only and fly from mid June to mid July.
In Iowa, June is the start of the busiest time for butterflies.  Many of the species that have only one generation per year fly when the days are the longest.  Species that have more than one generation each season will start their second flight in June.  The numbers rapidly increase.  With the longer days, you will have many more opportunities to encounter butterflies as well.
The first generation of eastern tiger giant swallowtails will persist through June, with the second generation appearing in July.  Black swallowtails can have several generations with steadily increasing numbers throughout the summer.  These butterflies are large and have fairly long adult life spans.  If you have large showy flowers in your garden, you might see particular individual members of those species visiting the same flower at approximately the same time each day.  Red admiral behavior is also fun to follow--late in the day, near sunset time, individuals will bask on tree trunks or on the side of a house, or even on different structures in your yard.  They chase any other butterfly they see, regardless of the species, then often return to the same spot to bask again.  They might return to a particular prime location for several evenings in a row.American lady
Cabbage white, clouded sulfur, and orange sulfur all become very common in June, and can be seen almost anywhere.  You may see little yellow anywhere its host plant partridge pea is found.  Look for dainty sulfur in the sandy areas along the Des Moines River.  They seem to be associated with the
cockleburs that grow in those locations.
There are a number of hairstreaks and grass skippers that have only one generation per year and fly in June.  A surprisingly high percentage of them can be found by inspecting common milkweed flowers on a regular basis.  You might also check dogbane and other types of milkweeds.
Purple cone flowers are good as well.  The point is to watch them on a regular basis and look for the small, easily overlooked butterflies that you might not see otherwise.  Watch for banded and coral hairstreaks, Peck's, Delaware, tawny-edged, and crossline skippers.  You may see other species that are less common as well.
Most of the brushfoot butterflies can be seen in June.  Painted ladies and American ladies can be found almost anywhere.  Watch for question marks mudding along trails in wooded areas.  Northern pearly-eyes and little wood satyrs can also be found along woodland trails.  Red-spotted purples and viceroys can also be seen easily.
One of the spectacular butterflies that can be seen most of the summer is the great spangled fritillary.  It is quite large, and visits backyard flower gardens readily.  It seems to have just one generation per year, although there can be fresh individuals for most of the summer.
You should plan on making a trip to a prairie sometime in late June or early July to look for regal fritillaries.  There have been good numbers in recent years, but typically they are only found in good prairie habitat.  This is a spectacular, monarch-sized brown butterfly, and well worth the time and effort needed to see them.
Days are long in June and butterflying is good.  But the season passes by fast, and you can miss the show if you are not outside.  So get outside and watch for butterflies.
 
   
  May 2021  
  Eastern tailed-bluesApril has had weather which has been somewhat inconsistent for butterflies--cool windy days, mixed with the occasional warm day.  We have even had some snow and frost.  We have had some good butterfly days and some bad butterfly days.  May should have days that are consistently better for butterflies, and the populations should start to increase.
Redbuds grow naturally in the southern third of Iowa.  If you hit one of those places--Red Haw, Elk Rock, Cordova, or Waubonsie State Parks to name just a few, and you look closely at the redbud trees or along the walking paths near those trees you might see a very small butterfly that looks black--Henry's elfin.  It is more of a brown color than black when you get the light on them, but they look black initially. Their flight only lasts for a few weeks in late April or May.  If you get out during the first week of May you might find some, or you might just be too late.  Henry's elfin can be quite frustrating.  I spent many hours looking for them before I finally had a little bit of success.
Cabbage whites have been on the wing, as have clouded sulfurs.  I have only seen one eastern tailed-blue so far, but I expect them to be out in large numbers soon.
I noticed what I thought was an abnormal absence of red admirals when I started writing this forecast, so I asked the expert on the species, Royce Bitzer, what was going on.  If you remember, a small fraction of this species seems to over-winter in Iowa, but most migrate in from states to the south of us.  Royce pointed out that we had a pretty cool spring, the jet stream was far to the south of us, and we had not had winds from the south that were warm enough (above 60 degrees F) and which had a high enough humidity (dew points above 55 degrees F) to support the migration.  Normally we have those conditions by mid-April, and this year we did not get those conditions until April 26.  So the bottom line is, the red admiral migration came a little late this year.  I have noticed that we are now getting good numbers of red admiral sightings on the web sites that track those things.
The butterfly numbers in May can be low.  Multi-generational butterflies have peak populations when most of the adults are flying, and May happens to fall between the peaks for most species.  eastern tiger swallowtail
The swallowtail species should be out.  The big three for central Iowa are the black swallowtail, the eastern tiger swallowtail, and the giant swallowtail.  The black swallowtail can be found in open fields.  Watch for the other two on flowering trees.  Crab apples, lilacs, or fruit trees are always good places to look for them. 
If you happen to live in either southwestern Iowa or southeastern Iowa, zebra swallowtails can be found in Waubonsie State Park and is Shimek State Forest.
Look for American ladies and painted ladies this month.  I usually see American ladies a little bit earlier than I see painted ladies.
Meadow fritillaries have been photographed in Iowa by several people.  They can be common in certain habitats.
Skippers that show up in May include the silver-spotted skipper, Peck's skipper, hobomok skipper, and the common sooty wing. 
Dusky wing skippers that are flying include Horace's, Juneval's, and wild indigo.  There are a few others that are rarer than those three.  All are difficult to identify even with a good photograph.
The weather is turning nice, and it is time to get outside and replace that Covid-19 paleness with a good tan.  You won't be sorry that you did.

Harlan Ratcliff
 
  Grapeleaf skeletonizer  
  March and April 2021  
 
Mourning cloakButterfly season is upon us.  Hopefully it is coming up fast.  But it doesn't come in with a bang. The sky will not be filled with butterflies. Instead, the season comes in with two or three species sunning themselves high on a tree trunk, or sipping sap from cracks in the bark where tree limbs have broken, or from holes in the bark drilled by sapsuckers.
While the late summer days with lots of butterflies are great, so are the early spring days after a long winter when you see just one or two little bits of optimism flitting around.
Butterflies which spend the summer as adults are the first you will see.  Around here they are the mourning cloak, the eastern comma, and the gray comma.  Compton tortoiseshell and Milbert's tortoiseshell also overwinter as adults, but are extremely rare in central Iowa.  You might see them if you are in northeastern Iowa, however.
The other butterfly you might see very early on is the red admiral.  Red admirals migrate into Iowa from southern states, but it seems likely that the early ones are the result of individuals which spent the winter in the pupa stage rather than migrate in.
As we get into the (usually) warmer weather of April we will start seeing other butterflies that have recently emerged from their chrysalis rather than just those that spent the winter in the adult stage.  We will also see the other migratory Vanessa species, the painted and American ladies.  The early April species include the cabbage white and the black swallowtail. red admiral Olympia marble was formerly found in central Iowa in small numbers, but is probably not present now.  However, it is a very secretive species and could be here and not seen.  If present, it would fly in early to mid April into very early May.  Unfortunately, it is most likely gone. 
In mid to late April you may be able to find spring azure in some of the wooded areas.  Henry's elfin uses redbud as a caterpillar host plant, and is found about the time that small tree blooms.  Look for it in the wooded areas along the Des Moines River, anywhere south and east of the city of Des Moines, and where there are concentrations of redbud.  I have found them on the ground or in low vegetation along walking trails.
By late April a good assortment of butterflies should be flying, including the eastern tiger swallowtail, clouded sulfurs, eastern tailed blues, juniper hairstreaks (they are found in central Iowa but are pretty rare here), pearl crescents, and question marks.
I usually admonish people to get outside and away from their screens during butterfly season, but there are some pretty good resources that are worth checking out which can enhance the experience.  The first is the book The Butterflies of Iowa by Dennis Schlicht, John Downey, and Jeffery Nekola.  It was published in 2007, and your library may have a copy. Amazon does seem to have some used copies for sale.  This book gives a lot of information about Iowa's butterflies that is more specific than the general field guides give.
Jim Durbin's Insects of Iowa site gives information on recent records for Iowa's butterflies.  Royce Bitzer, Ph.D. has a website with lots of good information about the migration patterns of red admirals and the painted lady species.  The Wisconsin Butterflies site tracks Wisconsin butterflies, but has a useful "recent sightings" page that tells us that mourning cloaks have been seen in Wisconsin, with the first of the year seen on March 8th.  inaturalist seems to have some really good information about butterflies but also records of a whole host of other species.  There is also an Iowa Butterflies Facebook page.  e-butterfly,  Butterflies and Moths of North America (BAMNA) and BugGuide all give useful regional information.
Last year was difficult.  Many of the state parks had restrictions.  Let's hope this year is better.  Butterflying is an activity that can be enjoyed individually or in small groups, but maybe some of the more social events can happen this year as well.
So get your nose out of the internet and get outside and look for butterflies.
 
  Grapeleaf skeletonizer