HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
  The Poweshiek Skipper Project  
 
Butterfly Forecasts for Central Iowa  
  May, 2019  
  HobomokI am not a particularly superstitious person but this has been an eventful year for me with lots of changes--some good, some that I did not want at all.  But life goes on, and after a long winter I was particularly looking forward to seeing the first butterfly of the year.  Others had reported seeing butterflies--March 29 was the first report I saw from Iowa, but Wisconsin had a sighting on March 18.  But it was well into April by the time I was able to take a little trip up to The Ledges State Park in hopes of seeing my first.  And I saw it on the trip up there--a red admiral flew up out of the road ditch and in front of my car.  Is it a bad omen if the first butterfly of the year ends up on your radiator grill?  If I had better reaction time I might have braked for it, but I am old and slow.
I'm not taking it as a bad omen, though, because I don't believe in that sort of thing.  Plus, I did not get a positive ID on it--I thought it was a red admiral, but it could have been something else--a grasshopper, perhaps.  And I did look at my radiator grill when I got to the park--no sign of a butterfly of any kind.
The first butterfly that I saw this year that I know I didn't kill was an American lady that I saw drinking nectar from a dandelion at Camp Dodge.  Since then I have seen several additional American ladies, red admirals, and painted ladies.  There have been some nice photos and sightings of those three species on the Iowa Butterflies Facebook page, and some exceptional photos of Henry's elfin as well.  The elfins have been reported from Polk City and Pammel State Park. 
On April 26 I visited Elk Rock State Park, specifically looking for Henry's elfins.  I have spent hours and taken many unsuccessful trips looking for this species.  However, in this day I was lucky.  I saw between a dozen and two dozen individuals.  The cold weather in the days that followed probably cut back the numbers, but there might still be some there.  Look along the horse trails to the east of the equestrian day-use camp.  Most were basking on the trail, although some were seeking nectar in the gooseberries and spring beauty flowers along the path.  But do it quickly because otherwise it might be too late.
May is sort of an odd time for butterflies.  The number of species that can be found in Iowa during the month of May is relatively high.  The problem is that most butterflies have a flight time that resembles a bell curve or a normal curve.  Some have a single generation per year, and some have two or more generations per year.  The peak times for those populations are usually not found in May--they are earlier for some species, and later for others.  So while you can see a lot of species the numbers can often be low.Viceroy
 Butterflies that can be found throughout the entire month of May include red admirals, eastern tailed-blues, clouded sulfurs, and cabbage whites.  Those butterflies are also among the most common throughout the butterfly season, and typically have more than one generation with overlapping flights.  Black swallowtails, eastern tiger swallowtails, and giant swallowtails are not as common but are large and showy, and can be seen through the entire month.  Individuals can live for several weeks, and if you have a flower garden or a lilac bush you might see the same individual visiting at about the same time each day.
Skippers start showing up this month as well.  Silver-spotted skippers can be found at any time during the month, although they will be much more common later in the summer.  Peck's skipper often shows up.  Hobomok skippers are showy and a little larger than Peck's skipper.  In my experience, they have been fairly common some years but mostly absent in others.
American copper can be found in very limited areas.  Although they can be found in May they are more likely later in the summer.  They are never very easy to find, however.  Bronze copper is more widespread, and can often be found around wetlands.  Still, its numbers are fairly low.
Look for eastern comma to be replaced by the slightly larger and similar looking question mark.  Question marks found in mid May can be spectacularly colorful, even though they disappear from sight when they fold their wings.
By the last week in the month the first viceroys and red-spotted purples show up.  By then, the butterfly season is well on its way.

Targets:

Eastern Pine Elfin
To the best of my knowledge, this butterfly has not yet been found in Iowa.  It has been found in Minnesota and Wisconsin, including at least one county adjacent to Iowa.  If it is here, it will be secretive and difficult to find.  It is also likely to be quite rare. There are a very few places in northeast Iowa where white pine grows as a native.   Look for it during the month of May.  Any photos or sightings should be reported and I will buy whoever documents one a nice cold beer.

Harvester:  Harvesters are small, distinctive butterflies that have been found in many locations throughout Iowa.  But they are never common.  I have been fortunate enough to see one on one occasion.  I would love to see one or more again.  Harvesters are predators in their caterpillar stage, living among and eating wooly aphids.  The wooly aphids seem to prefer alder or cottonwood trees, or greenbrier.  I have searched greenbrier for wooly aphids and found them, but so far have not been lucky enough to find any stage of the harvester butterfly.  

Good luck finding butterflies.  If it ever quits snowing in Iowa the season should get off to a good start.

Harlan Ratcliff
 
  banded hairstreaks  
  March and April, 2019  
  Red admiralThis is the tenth year for butterfly forecasts on my website.  It has been for the most part an enjoyable task to put them out but sometimes I struggle to keep the forecasts fresh and new.  March can be especially problematic.  It is a great thrill to see the first butterfly of the year, and that almost always happens in March.  That butterfly will probably be one of two or three species.  It will either be an eastern comma or a mourning cloak.  Sometimes it will be a red admiral. 
This year looks to possibly be an outlier.  The huge piles of snow outside as I am writing this suggest to me that the butterfly season will be late this year.  We might not see any butterflies in March this year.  So I am combining the forecast for March and April this year.
The snow is starting to melt and it might be mostly gone by the end of the month.  The butterfly season will start slowly and probably late, but it should progress rapidly once it starts.
 The butterflies which spend the winter as adults will show up first.  These include eastern comma, mourning cloak, and gray comma.  Then some of the migratory species show up--red admirals and American ladies.  Then, often by mid-April, cabbage whites and black swallowtails can be seen.  Azures can often be seen by the middle of the month as well.  It is unclear whether what we see are a first generation of summer azures (which have multiple generations), or spring azures, which have a single generation.  The whole situation with azures is confusing as there seem to be several species nationally, and those individuals have very subtle differences.  Whether those differences are big enough for the individuals to be considered different species is not clear, nor is the question as to what we have here.
Targets:
In order to change things up a little bit, I thought I would add a discussion of what I am calling "targets."  Targets are simply things that seem to be worth looking for.  The term might include rare butterflies but it might also include other creatures.  It might include something I have seen before, or it might include something I am hoping to find (or for someone else to find) that may or may not actually be found in Iowa.  It might also be some particular area that is worth searching in.  Three targets I have for this month are Henry's elfin, Olympia marble, and yucca giant skipper.
Henry's elfin:
Henry's elfin is a small hairstreak.  It is found only in some of the counties in the southern third of the state.  In Iowa the only host plant for the butterfly seems to be redbud.  Like several of Iowa's other hairstreaks, this butterfly seems to only have one generation per year.  In the case of Henry's elfin, the adult butterfly is only found for about a week each year.  The last week of April and the first week of May seem to be the time frames with the most records.  I have spent a lot of time unsuccessfully looking for Henry's elfin.  But while much of my searching was in vain, I also was lucky enough to find them on a few occasions.  A couple of times when I found them I found quite a few, and in locations where I had not expected to find them.Henry's elfin  Specifically, if you spend enough time hanging around redbuds sooner or later you will see the small brown butterflies flying around them.  The problem is that often you will not see them close up.  When I have looked for them this way I have only seen one or two at a time.  A couple of other times while walking along trails I saw quite a few of them.  They bask on the stems of brush or weeds a foot or two above the ground level, and they fly out and chase other individuals of the same species that get close.  I did not observe mating behavior, and the impression I have is that this is male on male aggressive displays, but I can't say for sure.  In spite of respectable numbers I saw on one occasion, the following week when I visited I saw none.
Olympia marble:
The Olympia marble is similar to Henry's elfin in that it might be more common than it seems to be.  It has one generation per year and only flies for a short time.   However, there are not as many recent records for the species as there are for Henry's elfin.  There is some thought that the Olympia marble has been extirpated from much of its range in Iowa, although it has been seen a few times   Most records for the species are in the western loess hills counties and a few counties in north eastern Iowa, although I do know of an individual who reported seeing them in The Ledges State Park, and even in Ames.  I have yet to see it, but I hope to sometime.
Yucca Giant Skipper:
A few years back Tim Orwig sent a message to the Iowa Insects list serve, asking if anyone in Iowa had looked for the yucca giant skipper.  It has never been found here, although it ranges widely across the United States.  Its host plants are various species of yucca, and the larva are root borers of the plants.  A link to a video by Dr. Andrew Warren, explaining some of the habits and a way to search for the species was included in the original email.  It can be found here
It is difficult to say when the adult would be seen if it is found in Iowa, but middle or late April might be a good guess.  I have looked for the adults, and have also looked at yucca plants to see if I can see any evidence of the larval feeding tunnels, but have not had any luck.  I am not prepared (or advising anyone) to break open the plants to look for the larva, but it might be interesting if someone could. 
I know some of you have already been out in the field.  Good luck looking for butterflies, and report them to the Iowa Insects list serve, the Iowa Butterflies facebook page, or Jim Durbin's Insects of Iowa site if you see some.
 
  banded hairstreaks