HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
  The Poweshiek Skipper Project  
 
Butterfly Forecasts for Central Iowa  
  September 2018  
  common checkered skipperSeptember brings the end of summer and almost the end of the butterfly season.  Butterflies are still out and are in good numbers.  Don't let the high numbers fool you, they will soon be gone.  But we can still enjoy them while they are here.  Maybe July or August has higher diversity, but September is not far behind.  Total numbers of butterflies can be highest in September, and that can be awe-inspiring.
Black swallowtail butterflies can be seen flying around, some quite fresh.  Giant swallowtails can be present in very high numbers if you happen to find a woodland that has a good population of the primary Iowa host of this butterfly, prickly ash.
Cabbage whites, clouded sulfurs, and orange sulfurs have been around since the very start of the butterfly season.  Those species have multiple generations, and over the summer each generation has more individuals than the last.  Numbers peak at the end of the season.  In the right locations, you might see clouds of these butterflies or huge numbers drinking water from the spaces between grains of sand near a puddle.
Little yellow, clouded sulfur, dainty sulfur, sleepy orange, and some others are not native to Iowa, but have similar habits to our native species.  They have multiple generations which overpopulate and overflow their habitats.  We get the excess butterflies which come in from areas to the south of us.
Growing up in Iowa there were a couple of things that I always assumed were true of everywhere.  Except that they are not.  The first is that dirt is black.  Most soil in Iowa is black, rich in organic matter.  Almost everywhere you go in Iowa the dirt is rich and black.  If you look closely enough you can find areas where the soil is mostly sand and is not black.  But most places away from Iowa and the upper Midwest the dirt is not black.  Perhaps we do not appreciate what we have.
The other assumption I have made has to do with the brilliant flowers we have all over all summer long and into the fall.  Often we think of them as weeds, but they are spectacularly beautiful flowers.  They include many variations of flowers that look like sunflowers--cup plant, compass plant, Jerusalem artichoke, cone flowers, and bidens.  They also include thistles and goldenrods. Our ditches and flood plains are covered with these tall, spectacular flowers especially late in the season.  Had we not torn up the prairie, the fields where corn and soybeans are grown would be covered with similar tallgrass prairie plants.  As natural as the landscape seems to us here, it is not seen everywhere.  The prairie, as little of it as remains, is a very special and spectacular part of Iowa and the upper Midwest.
Eastern tailed-blue is normally very common throughout the year, but numbers have been low for the most part this year.  I seen quite a few lately and expect to see high numbers until frost kills them off.  Look for Melissa blue as well--it has been seen in some parts of the state where it was not documented previously.  Gray hairstreak will show up in prairie areas or open fields.  It can be mistaken initially for eastern tailed-blue, but it is larger and the edge of the forewing is straighter than the blues.fiery skipper
One butterfly that is worth watching for this time of year is the American snout.  This smallish butterfly has what looks like a long nose--hence the name.  This butterfly is almost always found in small numbers in Iowa near the end of the summer.  In Texas, however, it can have huge irruptions and can be populous enough occasionally to require roads to be shut down.
Last year we had a very notable irruption and migration of painted ladies for a few weeks in the first part of September.  I would not expect to see something similar this year.  We still may see good numbers of them, and of red admirals as well.  Common buckeyes will be seen as well.  Late in the month, and later, watch for the winter form, which has unusual amounts of red coloration.
Pearl crescent will be present in fairly good numbers.  If you see crescents on fog fruit (the small flower in the fiery skipper photo) look at them closely.  I think phaon crescent may be an occasional invader, and fogfruit is its host plant.  Phaon crescent can look a lot like pearl crescent, and both species can be highly variable.
Monarch numbers have been pretty good.  At Camp Dodge we have some monarch research going on, and they documented a queen butterfly there.  As near as I can tell, it is only the fifth documented sighting of the species in Iowa.  Pretty exciting!
Several skippers will common as well.  Watch for silver spotted skipper, common checkered skipper, fiery, tawny edged, Peck's, least, and sachem skippers.
Watching butterflies in September is sort of like watching the end of a fireworks display.  You have seen and heard the fireworks going off, and while watching them you almost get used to the noise and the lights.  Toward the end the good stuff comes out, and then suddenly it is over.  So get outside.  The good stuff is out now, but it will be gone soon.

Harlan Ratcliff
 
  little wood satyr  
  August 2018  
  silvery checkerspotButterfly numbers continue to increase throughout the summer.  Many of our butterflies have more than one generation per year, and their numbers build up, sometimes quite rapidly, throughout the summer.  In addition, there are a number of butterflies that do not overwinter in Iowa but which migrate into the state during this time of year.
Clouded sulfurs, orange sulfurs, and cabbage whites are present in high numbers.  Eastern tailed-blues have very low numbers compared to normal, but still should be common enough that you will see some.  Summer azures will be around in small numbers but will fade away by the end of the month.
Monarchs have received a lot of attention lately and there have been conservation efforts by people who are not normally involved with the conservation of butterflies.  There have been efforts to plant milkweeds, even if only a plant or two in a yard with no other wildflowers.  It is hard to draw a line between those efforts and the actual numbers but where I have been this year monarch populations seem to be higher than  in recent years.   Maybe that is a trend, or maybe that is just normal variation.  Viceroy population numbers seem to be up, also, and there are no special conservation efforts for them. Viceroys should persist in good numbers through August, as should the other Iowa butterfly in the genus, the red-spotted purple.
Three swallowtails are fairly common in central Iowa, and they will all have good numbers in August.  Black swallowtails are more common in the prairies while giant and eastern tiger swallowtails use woodlands more.  All three will travel widely, however.  If you have large, long-lived flowers in your back yard or garden you might see a single individual visit those flowers at about the same time every day for a number of days.  They live long for butterflies and often follow a particular routine. 
In addition to the very common sulfurs mentioned earlier, there are several which do not survive Iowa winters but populate the state from areas to the south each summer.  The most common of these is the little yellow, which uses partridge pea as a host plant.  They will be found in high numbers everywhere there are clumps of this plant.  Cloudless sulfurs use partridge pea and other legumes, and can often be found in August, but in smaller numbers.  Cloudless sulfurs are quite large, however, and are pretty showy when they are around.  Sleepy orange looks quite a bit like the orange sulfur from a distance, but is a bit darker on the dorsal surface.  Common sootywing Some years large numbers of dainty sulfur can be found along Saylorville Reservoir, near the mile-long bridge that goes into Polk City.  The area that would normally provide the habitat for this butterfly has been flooded most of the summer, so I would not expect to find them there this year.
Pearl crescents and silvery checkerspots will be quite common.  In some prairie areas you should also find gorgone checkerspots.  Other brushfoot butterflies that might be present in numbers include the hackberry and tawny emperor, the question mark butterfly, and the eastern and gray commas. Battered great spangled fritillaries may still be seen throughout most of the month.
Red admirals, common buckeyes, and painted ladies are migratory and can be quite common.  They can be the among the most variable in numbers, being almost absent some years and filling the sky in others.
Several species of skipper can become quite common towards the end of the summer.  Common sootywing and common checkered skipper can often be found getting nectar from flowers along roadways.  Also easily seen will be the silver-spotted skipper, tawny edged skipper, Peck's skipper, fiery skipper, and sachem.
Watch the edges of roadways and puddles for butterflies "mudding".  Most of the butterflies that drink from the damp soil near puddles are males--they seem to concentrate the liquid for minerals.  Whenever there is a light rainstorm there will often be good concentrations of butterflies on the wet sand or dirt within half of an hour of the storm.
Butterfly numbers should be good in August.  Enjoy them while you can.

Harlan Ratcliff

 
  little wood satyr  
July 2018
  question mark butterflySummer is here and so is the peak of the butterfly season.  It has been an unusual season so far, with lots of rain.  I am not sure that I have a clear assessment of what is going on with the butterfly populations this year.  My survey numbers have been much lower than normal.  That seems to be caused by a combination of some of the usually common species (especially eastern tailed-blues) having sparse numbers and cloudy or rainy weather when I have tried to do surveys.   I also have relocated so I can't gauge the numbers I see in the afternoon or evening against past experience, because I don't have access to the same habitats.  Butterfly photography requires the ability to sneak up on them, and I have been having a hard time with that this year.  The butterflies tend to be startled when my arms are wildly flailing around swatting at mosquitoes or the little gnats that fly into my eyes or my nose.  Mosquitoes and gnats are present every year, but seem to be present in higher numbers than normal this year.
There might be an analogy with the overflow coolant tank on your car.  The overflow tank can be empty while there is still coolant in the radiator.  If you go to good habitats--prairies, woodlands, and wetlands that have diverse vegetation you will see fair numbers of butterflies.  If you go to the suburban back yards that do not have the caterpillar host plants or good supplies of nectar, the overflow of butterflies that often  populate these areas will not be there. 
If you have never seen a regal fritillary it is well worth your time to go searching for the species.  They are at their population peak in July.  You have to go to a pretty good prairie in order to have a reliable chance of seeing one.  Caterpillar host plants are bird's foot violet and prairie violet.  If you get out in the middle of a prairie and stay there long enough you are likely to see them flying by.  With luck you might even get close to one.  If you need a hint as to where to start, you should check out the list of sightings at the Insects of Iowa website.
While you are visiting a prairie, you should check any milkweeds they you see for butterfly visitors.  The association that monarchs have with milkweeds is well known, but the various kinds of milkweeds are also great sources of nectar and are visited by many types of butterflies.  Many of the small but colorful hairstreaks (coral, Edwards, banded, hickory, striped) visit milkweeds and then remain on the bundles of flowers for relatively long periods of time.  Many of the skippers also visit milkweeds, but are generally more active than the hairstreaks.  Look for Delaware, little glassywing, crossline, dun, and tawny-edge skippers here.  If you are at one of the diverse prairies you might see some of the more rare skippers as well.  Two-spotted skipper and byssus skippers are always targets for me, but I have only seen each of those species once.
meadow fritillaryMonarchs have generally been more common this year than most.  I have also seen fairly large numbers of great spangled fritillaries.  Certain locations have had good numbers of meadow fritillaries.
Question mark butterflies can show up in wooded areas.  They look similar to the eastern commas that we see first thing in the spring, but the punctuation mark on the side of the hind wing is different.  Also, they are typically slightly larger, and have longer and skinnier tails on the hindwing.  The basic color is brown, but there can be a great deal of variation within individuals.  Some, like the individual shown above, can have a lot if intricate color.
The three most common swallowtails (black, giant, and eastern tiger) should all be present this month.  You may see some individuals that are quite beaten up and old, and you may see some fresh ones as well.  If you have a flower garden you might see an individual swallowtail visiting a particular group of flowers at about the same time each day for a number of days.
Hackberry emperors are likely to come out of the trees and land on you if you walk in a trail near where they are hanging out.  Red admirals will do the same, but hackberry emperors are the most likely.
One of the most common butterflies in prairies right now is the common wood nymph.  They can be hard to photograph, though, because while they readily fly up so they can be observed they then fly back down into the tall grasses so that it is hard to get a good view of them.  Northern pearly-eye looks and acts in a similar fashion, but is more a butterfly of wooded areas.  If you happen to visit wet prairies in the northern part of the state you might see the eyed brown, which acts about the same.
Pearl crescents will continue to be common this month.  We should also be seeing silvery crescent spots but I haven't seen any yet this year.  Eastern tailed-blues have been mostly absent this year.  Clouded and orange sulfurs are around, but their numbers seem lower than most years.
Eastern tailed-blues have been mostly absent, but there have been several sightings of melissa blue in southern Iowa.  I saw one myself just today (June 30) along the road to Medora prairie.
Get outside.  Never mind the bugs.  Take plenty of water and don't get overheated.  But get outside.  You will be glad you did.

                                                  Harlan Ratcliff
 
  little wood satyr  
  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