HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
  The Poweshiek Skipper Project  
Butterfly Forecasts for Central Iowa  
  June 2018  
    Least skipperJune is a great time to see butterflies.  Species numbers and diversity rapidly increases.  For the last several years I have been tracking the first sighting for each species of butterfly in Iowa.  Typically June has the most first of the year (FOY) sightings.  During the first two weeks of the month I usually average one to two FOY butterflies per day. 
We are going into the season's rapid expansion of butterfly numbers.  On Memorial Day weekend I drove up to Hoffman Prairie, near Clear Lake Iowa.   I spent about an hour on the prairie, then went to McIntosh Woods, which is nearby.  I saw a grand total of zero butterflies.  Chris Edwards and Mark Brown spent some time the same weekend in southern Iowa, Chris in Shimek State Forest and Mark in Stephens State Forest, and both reported their results on the Iowa Insects listserve.  Chris found 20 species and Mark found 26 species.  Both had total numbers well over a hundred.  Chris and Mark are both probably better at locating butterflies than I am, and spent more time than I did.  However, a big part of the difference was that northern Iowa got some very severe late season snows, and the season is therefore delayed in the north compared to the south.  The butterfly population increases rapidly in just a few days, typically in late May or Early June.  The numbers will continue to increase throughout the summer.
All of the swallowtail species should be flying now.  You will see eastern tiger swallowtails and giant swallowtails in gardens and woodlands.  Black swallowtails go more for prairies and clearings. 
Gravel roads and the weeds alongside those gravel roads are great places to look for butterflies.  Clouded and orange sulfurs will become quite common.  Watch for eastern commas and question marks sipping moisture from the grains of sand along the roads. 
If you walk along those roads on a hot, humid summer day you might find yourself sweating.  If you do, you are also likely to have a butterfly come land on you.  If that happens, I would give odds that it is a hackberry emperor.  Several species will land on sweaty humans, but hackberry emperors are known for it.
My photo of a least skipper shows the small white flowers of dogbane.  This is a plant that is related to the milkweeds and, like the milkweeds is very attractive for butterflies.  I have had pretty good luck watching for butterflies on patches of dogbane.  It is especially good for many of the small skippers.
hackberry emperorLater in the month common milkweed will be in bloom.  Common milkweed is a great place to look for several of the grass skippers.  I have seen dun, little glassywing, and crossline skippers all on the same flowers patch of milkweed.  Since these little butterflies are very similar in appearance it usually takes a good photograph to get a positive ID.
Other skippers that show up will include Peck's, tawny-edge, Delaware, least, and silver-spotted.
There are two common species of blues in central Iowa.  The summer azure is light blue above and flies up into the trees.  The eastern tailed-blue is darker blue or gray, and flies lower to the ground.
The gray copper is fairly large for a gossamer winged butterfly, and therefore can be quite conspicuous.  It is usually fairly common where it is found, but will not be seen at all in other areas.
Bronze copper is smaller, but very spectacular when seen.  It seems to be less common now than it once was.
There is a group of hairstreak butterflies that are rarely seen, but can often be found on milkweeds--common milkweed or butterfly milkweed especially.  These hairstreaks typically only have one flight per year, and live as adults for only a short time.  The group includes the banded hairstreak, coral hairstreak, Edwards hairstreak, and the much rarer hickory and banded hairstreaks.
Fritillaries will be showing up as well.  Meadow fritillary is small, but can be fairly common most years.  Great spangled fritillaries put on quite a show in the backyard gardens.  Variegated fritillaries are occasionally seen in small numbers, but more often seen singly. 
Regal fritillaries will start to emerge by the end of the month, and are well worth taking the time to search out.  They are prairie obligates, so you have to go to a pretty good prairie to seek them out.
June is a great time to see butterflies, so get outside and look for them.

See you outside.

Harlan Ratcliff

  Little wood satyr  
  May 2018   
  Silver-spotted skipperSpring is finally here and the butterflies have been slowly showing up.  This year they have been delayed compared to recent years.  Still, they are welcome.
As far as I know, the first butterfly recorded in Iowa this year was an eastern comma noted by Barb Manning on April 10 in Windsor Heights.  There was another eastern comma noted at Effigy Mounds National Monument on the 12th.  We had a couple of weekends with snow after that.  Mark Brown noted several red admirals, a mourning cloak, and an eastern comma at Shimek State Forest on April 20th.  I did not see any butterflies until April 28th, when I made a trip to Waubonsee State Park on the southwest corner of the state.   I expected to see some of the common species--mourning cloaks, cabbage whites, azures, and red admirals, and I did see at least one of each.  I thought if I was lucky I might see one or two Henry's elfins.  In fact I saw a lot--maybe close to two dozen.  I also was hoping to see zebra swallowtails, but I thought it might be too early for them to be out.  I was not too early--they were out in numbers as well.  I did not get a photograph that I thought was particularly good but I did get a lot of great looks at this spectacular species.  Chasing butterflies with the intent to photograph them is a little bit like fishing.  You can spend all day, come back empty-handed, and still consider it a good day. 
Zebra swallowtails are mostly only found in a couple of sites in Iowa, in Waubonsee and in Shimek State Forest on the southeastern corner of the state.  Eastern tiger swallowtails, giant swallowtails, and black swallowtails should all show up in May.  All three of those species have relatively long life spans for butterflies--they may live for several weeks in the adult stage.  Swallowtails make quite an impression, even when they are present in small numbers.
Cabbage whites are out already.  Clouded sulfurs should follow within a week or two.  They will soon become quite common, and will be one of the most common butterflies throughout the season.
Two small blue butterflies are far and away more common than any of the other blue butterflies seen in Iowa.  The spring/summer azure complex is fairly complicated.  Iowa may have two or more of the azure species but telling them apart requires netting them and examining them up close.  Typically a photograph from one angle is not enough to show the subtle differences.  The summer azure is probably the one seen most often.  The other common blue butterfly is the eastern tailed blue.  It is fairly easy to tell those two apart--the azure is lighter blue and flies up into the trees.  The eastern tailed-blue is darker blue or gray from above, and flies at a lower level.  Both the eastern tailed-blue and the summer azure have multiple generations and may be seen in small numbers in the first part of May, and will be seen in larger numbers in late May going into June.eastern tailed-blue
Some other possibilities within the gossamer-wing group include juniper hairstreaks, bronze coppers, and American coppers.  All can be found throughout the state, but might be more common in certain habitats.  I find them difficult to find on a regular basis but it is not too uncommon to accidentally run across them.
Red admirals have already made an appearance, and will be seen often in back yards.  They like to find a sunny spot on a tree trunk or any other place they can perch, and they wait until another red admiral or anything they can mistake for a red admiral goes by.  Then they take off in hot pursuit.  American ladies and painted ladies can often be seen getting nectar from the spring flowers.  Eastern and gray commas will be present, but will be replaced later in the month by the slightly larger question mark butterfly.
Pearl crescents and meadow fritillaries may be present from fairly early in the month, and silvery crescentspots, red spotted purples, and viceroys will show up later in May.
Skippers that show up in May include the silver-spotted, common sootywing, peck's, and tawny-edged skipper.  I have seen them all on the alien wildflower Dame's rocket.  There were a couple of years when I first started taking photos of butterflies that I would see large numbers of hobomok skippers on those flowers in May.  Recently I haven't seen them at all in the same locations. 
Sometimes one species will be really common.  At other times they can't be found.  The populations of butterflies in early May will be fairly low, but will pick up pretty well towards the end of the month and really go to town in June.  It slowly gets better.
Get outside.  See the butterflies.

Harlan Ratcliff
  Little wood satyr  
  April 2018  
  Cabbage whiteI was watching the weather forecast the other day and the meteorologist said that he was very tempted to give the forecast that he wanted, rather than what it will actually be.  So am I.  But his inaccurate predictions probably have more severe consequences than mine.  If you get rained on when you are expecting sun you might get angry.   Hopefully if you see a different butterfly than I predict you will see it won't have the same negative consequences as a bad weather forecast.
This year has been pretty slow for butterflies because of the cool weather.  I have heard of no reports of butterfly sightings in Iowa for March this year--we have only had a couple of days that were warm enough for them to be flying.  There have been several sightings in Wisconsin, per the Wisconsin Butterflies site.  The weather forecast for the first week or so of April seems to be pretty unfavorable for butterflies but spring will get here eventually.  When it does, we should see the butterflies that normally show up in March.  Butterflies that spend the winter as adults and emerge on warm spring days include mourning cloaks and eastern commas.  Gray commas, and Compton's tortoiseshells are not common around here but could also show up early in the spring.  Once the days start to heat up other butterflies will not be far behind.  
Cabbage whites often show up in early April.  It will be at mid-April at the earliest this year.  This species is common state wide.  A couple of other white butterflies might be seen--the checkered white has two flights, including one in April.  Olympia marble has only one flight, usually in early April to late May.  Both come from fairly specific habitats and feed on wild mustards.  Checkered white is often seen in its second flight, which occurs later in the summer, but not so often in April.  Olympia marble is historically reported from the Loess Hills area in the western counties of Iowa, a few counties in northeast Iowa, and Story and Boone counties.  It is notoriously difficult to find, which may be because it only flies for a short time in restricted habitats.  There have been some suggestions, however, that like several other butterflies it is no longer found in Iowa.  It is certainly worth looking for, though.  The most recent sighting on Jim Durbin's Insects of Iowa website was from 2006.Henry's elfin
Another butterfly that has a short flight time is Henry's elfin.  It can only be found in late April through early May.  Henry's elfin has uses several caterpillar host plants across its range, but in Iowa it specializes in redbud. It is found in the southern part of the state. This is a very small butterfly that looks pretty dark when it flies.  You have to look close and be in the right place to find it.  I have seen them in Cordova Park and Elk Rock State park, both of which are in Marion County.
Spring azures should start showing up about the end of the month.  If the weather is warm enough eastern tailed-blues will be around in April.  Other early butterflies include clouded sulfurs, eastern tiger swallowtails, black swallowtails, and American ladies.  Red admirals can show up early as well.

But the weather forecast has a great impact on butterfly numbers.  As I am writing this, there seems to be no good butterfly weather in it.  The warm weather will come.  But it seems to take so long...

Harlan Ratcliff 
  Little wood satyr  
  March 2018  
  Red admiralDon't you just hate winter?  Earlier last week I tried to get in my car but the doors wouldn't open because of the ice that was caked on it.  I had to tap around the edges of the door before I could get it open to get my ice scraper out.  Then I had to do the same with another door.  I started the car, but had to let it heat up for about twenty minutes before I could even get to the ice to scrape it.
We have had mostly dry weather earlier in the winter, and now we are getting that stuff the forecasters call a "wintery mix." But the days are getting longer, a few minutes per day.  And the weather will get warmer as well.
The butterflies are coming!
In most years the first butterflies of the year are spotted in March.  Sometimes it is not until the end of the month, but just as often they can show up during the first week.  2017 and 2016 were exceptional years, though, with early butterfly sightings in February.
Mourning cloaks and eastern commas spend their winters in Iowa in the adult stage, and are the most likely to be seen early on.  Gray commas and compton tortoiseshells have similar life cycles and might be possible as well, but they are not very common here so are less likely to be seen than the other two.
If you walk in the woodlands on a sunny March day, watch for sunny branches up high where you might see the eastern commas basking.  Look for moisture on the bark of trees.  That can be an indication of sap leaking from a crack in the bark or perhaps where a branch meets the main trunk.  It can also be caused by small holes drilled into the bark by sapsuckers (a type of woodpecker).  Early butterflies use that sap as a source of food, as flowers are not yet blooming.
Red admirals are generally considered to be migratory in Iowa.  They have been observed flying south in the winter and a different generation re-populates the state in the spring.  Large numbers can show up in the spring, often late April, but if the weather cooperates they might show up as early as March.  In additon to the migration, however, red admirals seem to have a little bit of plasticity in their life cycle.  In warm winters some individuals may be able to live through the winter as either adults or some other stage.  Last year, some of the first butterflies seen in Iowa were red admirals.eastern comma

Cabbage white butterflies spend the winters in the pupal stage, and are therefore very early butterflies as well.  Typically they start flying in early April, but they might show up in March if the weather cooperates.
The numbers will be small, and the total number of species that could be seen will also be small.  Still, one or two butterflies are better than none, and are a sign of things to come.
So get out in the wild areas of Iowa when you can.  Enjoy the sights, sounds, and smells.  Watch for butterflies.
Warmer weather is coming.  Butterflies will be here before you know.

Harlan Ratcliff

  Little wood satyr