HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
  The Poweshiek Skipper Project  
 
Butterfly Forecasts for Central Iowa  
  July, 2017  
  Monarch, great spangled fritillary, and thick headed flyIn Iowa in July, butterfly numbers are normally good, and the diversity is close to its peak.  This year the news might be a little mixed, however.  The surveys I have done have shown numbers to be quite a bit lower than normal.  I seem to be hitting mostly cool days, which might explain part of the problem.  Two species that are normally very common, orange sulfurs and eastern tailed-blues, are present but in greatly reduced numbers compared to this time most years.  Those two species usually account for about half of the butterflies I see each year.
There does not seem to be much drop-off among most other species, however.  Dr. Royce Bitzer has reported very high concentrations of red admirals in certain locations, and apparently there are small local outbreaks of painted ladies as well.  There have been reports of early sightings of southern migrants, some of which are very rarely seen in Iowa.  Aaron Brees reported common buckeye, sachem, and a cloudless sulfur, all of which can usually be seen later in the summer here.  He also reported three southern dogface, which are usually pretty rare here.  Southern strays reported in earlier forecasts include goatweed leafwing, zabulon skippers, and (possibly a southern migrant) white M hairstreaks.
The North American Butterfly Association (NABA) Fourth of July butterfly count posted by Chris Edwards had about half of the average total numbers, but the average number of species, including sightings of another southern butterfly, pipevine swallowtail.
The first part of July is a great time to find several of the small, inconspicuous, and rarely-seen hairstreaks.   Milkweeds are a pretty good place to start the search.  For some reason hairstreaks are very much attracted to milkweeds and spend a lot of time on them.  Common milkweed is good, but butterfly milkweed seems to be better. Coral, banded, and Edward's hairstreaks can all be seen in late June and early July, and can be found on milkweeds.  I have yet to see a striped hairstreak, but Eileen Miller posted an excellent photograph of one on the Iowa Butterflies Facebook page.
Butterfly milkweed ranges in color from bright orange to a deep red.  On a good prairie it can be seen from some distance.  It is a special experience to see butterfly milkweed from 100 yards away, then  when you make your way to it to find one or sometimes many small hairstreaks nectaring on the flowers.  It is even more magical to see hairstreaks chasing each other around a tree.  Many of our hairstreaks have certain trees as caterpillar host plants, and the males perch near those trees, waiting for mates.  They fly out and chase other butterflies--sometimes females of the same species, but often males or butterflies of other species.  It is a fairly standard behavior among hairstreaks and is pretty entertaining to watch.
Swamp milkweed usually blooms after butterfly and common milkweed.  It should be blooming by the middle of July.  Swamp milkweed is also pretty attractive to butterflies, but it seems to have certain times when it is more attractive than at other times.  I have walked past it when it was completely bare of butterflies, and seen it loaded at other times.  In the photo above there is a monarch, two great-spangled fritillaries, and a thick-headed fly (possibly Physocephala tibialis.)silver-spotted skippers
Little glassy-wing and dun skippers can often be found on the same common milkweed blooms during the last week of June and the first week of July.  They can be very difficult to tell apart.  By the middle of the month, little glassy-wings have been replaced by crossline skippers, which are also very similar-looking to duns.  Delaware skippers, least skippers, and tawny-edged skippers will be common, and fairly easy to identify with practice.  Peck's skipper, common checkered skipper, and common sootywing can also be present and are fairly easy to identify. 
Silver-spotted skippers are not uncommon, and are quite charming.  They are larger than any other Iowa skipper, and can often be found in rural habitats.
Any of the swallowtails can be found during the month of July.  The most common in central Iowa are the eastern tiger, giant, and black swallowtails.  Other large butterflies that can be seen now include monarchs, viceroys, red-spotted purples, and great-spangled fritillaries.  You should try to visit a good prairie and see the magnificent regal fritillary.  Rolling Thunder and Medora prairies are real good places to see them.
One of the most common butterflies to be seen in July, especially in grassy or prairie areas, is the common wood nymph.  It can be somewhat frustrating, though.  It is easy to scare them up simply by walking through the prairie.  Then they fly for a short distance and dive down into the grass.  There they can be difficult to see, and especially difficult to photograph.
Pearl crescents and silvery checkerspots should be common, and not too difficult to photograph, especially on cone flowers of black-eyed susans, where they like to get nectar.  Watch for the rarer gorgone checkerspot also, especially in the good prairie areas.
Gray coppers should be out for the first part of the month, but they are usually gone by the end of the month.
Little yellows should start showing up anytime soon.  They use partridge pea as a host plant, and can usually be found in good numbers anywhere this plant grows.  Dainty sulfurs should start showing up as well.
I have not seen checkered whites for a couple of years, but others have.  Maybe I will see one or two of them this year.
Summer is slipping by, so get out and enjoy the butterflies while you can.

Harlan Ratcliff


 

 
  henry's elfin  
  June, 2017  
  Little wood satyrThe days are really starting to heat up and soon so will the butterfly watching.  Populations can be low during the last few weeks of May but typically increase rapidly in June.  This year that rapid increase in populations might come a little bit later because of the extended periods of cool rainy weather we had in May. 
There were some interesting reports of sightings in May.  There was at least one additional sighting of a goatweed leafwing, and two white M hairstreaks.  The white M hairstreaks are particularly exciting because only a handful of records exist for the species in Iowa.  In The Butterflies of Iowa (see the reference in the March forecast)  the species is discussed, and it is suggested that it is probably a southern stray, or that it may be more common than we know because it mostly only flies unseen in the canopies of tall oak trees.  Other unusual sightings include large numbers of zabulon skippers at Shimek State Forest.  The southern stray idea, given our warmer than normal winter this year, might explain those sightings. Watch for these species all summer long, though, because they are all thought to have more than one generation in Iowa.
In the early part of June we should see eastern tiger, black, and giant swallowtails.  Clouded and orange sulfurs have made appearances already, but their numbers seem to have temporarily died back.  Their numbers will slowly recover, and by the end of the month may be the most common of our butterflies.  Red admirals can be seen in back yards, particularly near sunset.  They perch on the ground or in trees, and fly out to investigate anything that flies nearby. 
Silver spotted skippers and tawny edged skippers are flying now, and Peck's and least skippers should be flying soon (they have already been reported for Shimek).  Normally I would be seeing summer azures and eastern tailed-blues by now, but I don't really expect them until maybe the second week in June or later, because of the recent cool weather.
By the end of the month we will be seeing much greater numbers and many more species.  Look for little wood-satyrs here within a week or two--once again, they have already been seen in the southern part of the state. 
June has a steady progression of new and different wildflowers, some of which can be very good places to look for butterflies.  I especially like dogbane, which is a relative of milkweed (or possibly is a milkweed, depending on which expert has the latest word on the matter).  It stands about three or four feet high, and has small white flowers which are very attractive to skippers of all kinds, and larger butterflies as well.little glassy-wing  Dogbane should be blooming by about the second week of the month.
Pale purple coneflower might be blooming by then as well, and purple coneflower should bloom just a little bit later.  Both are very good spots to watch for large butterflies--great spangled fritillaries, swallowtails, and others are attracted to these. 
Eastern commas, question marks, and northern pearly-eyes are not often found on flowers but I have found all of them on purple coneflowers.  They are more likely to be found mudding and are more easily attracted to rotten fruit than to flowers, however.
Pearl crescents will be likely be common everywhere, and silvery checkerspots will be common in the woodland areas (but still often encountered in prairies).
By the end of the month the common milkweed and butterfly milkweed should be blooming.  Both are well known as host plants for monarchs (which should be flying in fair numbers by mid June).  What may not be known is how attractive both flowers are to other butterflies, particularly small skippers and hairstreaks.  A couple of plants on the edge of the gravel road across from my house were crawling with little glassywings and dun skippers last year in the last half of June.  Small butterflies like skippers and especially hairstreaks can often be found on common milkweed and can be seen from a pretty good distance because they break up the spherical outline of the flowers.  Of course, if you know of a prairie or savannah with good populations of butterfly milkweed and oaks or hickories you are almost guaranteed to find some of the hairstreaks that are rarely seen otherwise.
Viceroys and red-spotted purples should be out by early to mid-June.  Hackberry emperors will come out and land on you if you hike a woodland trail or canoe one of Iowa's slow rivers, especially if you sweat just a little bit.
Harvester butterflies would be a rare find.  Their caterpillars are predatory on woolly aphids.  They have been documented on greenbrier in the southern United States, and I have found woolly aphids on greenbrier in Iowa (but I have not yet found harvesters or their caterpillars on it).  Greenbrier grows pretty much all across the state, so I plan to inspect those plants whenever possible.
If you haven't yet seen regal fritillaries, you owe it to yourself to go to a good prairie to try to see them.  They should be flying in good numbers by the end of the month.  If you watch any large butterfly going by you should be able to identify one.  They are the size of a monarch, but once you see one they are easily recognized.  The Insects of Iowa website is a good place to start if you don't know where to go.  Be sure to get permission before going on any private property.

Happy butterfly hunting.

Harlan Ratcliff

 
  Henry's elfin  
  May, 2017  
  Peck's skipperWith May the butterfly season is getting off to a good start.  There have been a number of pretty good sightings, including some fairly rare species.  Cool cloudy weather in the last few days of April put a damper on my plans to attempt to find several seasonal and rare butterflies.  Still, the trend is positive.
Red admirals are constantly patrolling the back yards, and staking out their territories.  Red admirals will visit flowers and you may see them there.  However, you are more likely to see them a little before dusk, basking on a tree trunk or the ground, and flying out to chase anything that flies past. 
As more flowers start to bloom we will start to see butterfly activity around them.  Cabbage whites have been around since the first part of April, and will be joined by clouded sulfurs and orange sulfurs as the butterflies seen most frequently at flowers.  This year has seen a large number of painted ladies and American ladies as well.
 Eastern tiger swallowtails have already been out, and we should see black swallowtails as well.  Giant swallowtails are typically a little later, but we should be seeing them by the middle of the month.  Zebra swallowtails can only be found reliably in the southwestern and the southeastern parts of the state.  There has been one sighting already this year in Waubonsie State Park.
You may be able to see spring azures in the early part of the month.  By the end of the month they are replaced by summer azures.  Eastern tailed-blues should start showing up in fairly good numbers in early May as well.  Pearl crescents and silvery checkerspots will occur in good numbers as well.
One butterfly that is usually pretty uncommon in Iowa has been seen by at least three different observers, and in three different locations recently.  The goatweed leafwing is a brushfoot butterfly that looks like a dead leaf when its wings are vertical and it is viewed from the side.  From above it is orange with faint markings.  This butterfly is usually considered to be an occasional stray, with a possible resident colony in Waubonsie State Park (where one of the sightings occurred.)  The other sightings were in Shimek State Park and in Geode State Park. 
Goatweed leafwingSome of the skippers should start showing up, including Peck's, hobomok, common checkered skipper, common sootywing, and silver-spotted skipper.  Juvenal's duskywing has been around for a while, and should continue through the first part of May.  Several duskywing species are flying and they are all difficult to identify.  Juvenal's would be the largest and most likely, but Horace's, wild indigo, columbine, and sleepy duskyings are also possible. 
Meadow fritillaries have been common enough to be seen in recent years, but can be totally absent in other years.  Another butterfly that seems to vary in numbers from year to year is the bronze copper.  In my estimation, populations of this species have been pretty low for the last few years.
Look for viceroys and red-spotted purples (a.k.a., red-spotted admirals) in about the last week of May.
As always, I find May to be full of human social activities that interfere with chasing butterflies.  Don't let that interfere with your ability to get outside.  A lot of our problems would seem less significant if we would spend more time outside and less time doing things that other people expect us to do. 

So get outside when you can.  Chase the butterflies.


Harlan Ratcliff
 
  Henry's elfin  
  April, 2017  
  It is April, and we are starting into Spring.  We are in a pattern of cool, cloudy, rainy weather which is not generally good for butterflies. eastern tailed-blue Still, there have been a few observations.  Eastern  and gray commas and a red admiral have been seen recently, adding to the late February sightings.
When the weather gets a little warmer and we start seeing the sun we should be able to see more butterflies.  We will see more of the ones we are seeing now, that mostly have spent the winter in Iowa in the adult stage--eastern and gray commas and mourning cloaks.  We will see those butterflies that spent the winter in areas to the south of Iowa as adults, and migrated with the winds that follow the thunderstorms.  That includes the red admirals, American ladies, and painted ladies.  And we might see the first of the butterflies that spent the winter as a caterpillar or a chrysalis, like the cabbage white.
If you can get to a good woodland, one with lots of spring flowers, make sure you go there.  Take a camera and a field guide if you don't know the flowers.  Look for bloodroot, hepatica, snow trillium, spring beauty, Dutchman's breeches, wild ginger, and any others you can find.  Get down on your belly to get photos looking up at the flowers.  Feel the soft earth and smell the smells.  This has nothing to do with butterflies but it has something to do with life.  We should spend more time in the woods chasing butterflies and looking at flowers and less time chasing whatever else it is we are chasing in our lives.
Toward the end of the month as the days steadily get warmer we might see small blue butterflies in the woodlands that fly anywhere from eye level to treetop level.  These are probably spring azures, Celastrina ladon.  The genus Celastrina contains the azures, and is a group of butterflies consisting of a number of species or subspecies with subtle differences.  There is also a summer azure, C. neglecta.  The spring azure has only one generation while the summer azure has several.  If you see one in early April it is probably a spring azure, although some experts (mostly from states east of here) claim to find summer and spring azures at the same time, and to be able to tell the difference.  I must confess that I can't.  I do think Iowa has both species, though.
By the last week of April eastern-tailed blues will be flying.  They typically fly from eye level to lower levels, and very seldom fly up into the trees.  Their upper wings are dark blue in the males and brown or gray in the females.  The upper wings of azures are lighter blue than that of the male eastern tailed-blue, and both sexes are blue above.  Female azures have a wider black edge around the forewings than the males.
Black swallowtails and eastern tiger swallowtails should be flying in central Iowa by the end of April.  Zebra swallowtails might also be flying by this time as well, but are only found in the southwest corner of the state (Waubonsie State Park) and the southeast corner (Shimek State Forest).
Henry's elfinApril can be a good time to hunt for some hard-to-find butterflies also.  Juniper hairstreaks use eastern red cedars as a host plant, and usually have two generations in Iowa.  The first generation emerges in late April, and the second comes out in July.  Juniper hairstreaks are more common in the eastern counties of Iowa and in the Loess Hills on the west side of the state.  They are also found in the central part of the state, but seem quite rare and hard to find here.  I have seen them on my property in Dallas County twice, both times more or less by accident.  I have searched for them here dozens of times, and been disappointed by my lack of success.
Henry's elfin is difficult to find in Iowa, but it might not be all that rare.  It is very small, and only flies for about a week or two out of the year.  The last week of April is probably the best time to look for it.  While it uses several caterpillar host plants, in Iowa it probably only uses redbud, which limits it to about the southern third of the state.  I have seen it at Cordova State Park and Elk Rock Park, which are on opposite sides of Red Rock Reservoir (the Des Moines River).  I don't have that much experience with the species, but one time I did find about half a dozen and was able to spend about an hour taking all the photos I could of them.  I initially saw a couple by sitting in a lawn chair by a redbud tree.  That time it probably took close to an hour before I saw one, and it was not close enough to take a good photo.  I was able to positively identify it, though.
Olympia marbles are small white butterflies that use various mustards, particularly rock cress, as host plants.  They are also only found in the early spring--late April and early May.  They have always been difficult to locate, but there have been so few records lately that some of our butterfly experts are suggesting that they could be extirpated from the state.  I hope that is not the case.  If they are still found here they would be most likely to be found in the western part of the state, in the Loess Hills.
Yucca giant skipper has never been documented in Iowa, and it would be an exciting find if it could be found.  It is large--almost as large as a silver-spotted skipper.  If it could be found here, it would most likely be found in the last week of April or the first week of May (although we really don't know for sure). The caterpillar is a stem and root borer of yucca, and it might be possible to detect the presence of  butterfly by the characteristic frass it leaves behind on the damaged yucca.
This time of year gets pretty busy with school events and social events.  Make sure you find some time to get out in nature and recharge your batteries. 

And I am not talking about the batteries on your cell phone.

Harlan Ratcliff

 
  Henry's elfin  
  March, 2017  
  Mourning cloakWe have made it mostly through winter, and finally we might have some spring.  March brings the butterflies--a few at a time, and in fits and starts.  We had a very warm stretch in February.  Normally we never see butterflies in February in Iowa, but there were a couple of sightings in Iowa--a red admiral at Cone Marsh on February 18, and an eastern comma in Iowa City on the 23rd.  There were a dozen sightings of eastern commas in Wisconsin and one in Sarpy County, Nebraska.
But then the weather changed again and we all had to put on our winter coats and get our snow shovels back out of the garage.  Such is Iowa weather.
The February sightings were likely early records.  Eastern commas are known to overwinter as adults, and are always among the first butterflies seen.  The red admiral was a little surprising--conventional wisdom is that they spend the winters to the south of the state, and repopulate through northward migrations.  In The Butterflies of Iowa by Schlicht et. al., the authors suggest that while large numbers of the species sometimes enter Iowa through migration, there are always early individuals in the spring that may have overwintered as either adults or pupa.  It is probably impossible to tell what this individual was, especially from just a sighting, but it seems more likely that it overwintered in some form than that it migrated.
The ten day forecasts that I have seen do not predict butterfly weather--the highest temperatures look to be only in the high fifties.  But once we hit the mid sixties or seventies we should start seeing butterflies again, especially if the low temperatures are above freezing.
The first butterflies seen are usually those that over winter as adults.  In central Iowa, that usually just means eastern commas and mourning cloaks.  Gray commas and the tortoiseshells--Milbert's and Compton--are possible but are usually rare in this part of the state, so are unlikely to be seen.
Eastern commaLater in the month we will see the butterflies that spend the winter in some form other than the adults.  The first of this group may include red admirals, cabbage whites, spring azures, and black swallowtails. 
The early butterflies don't usually have access to flowers, so instead look for them on tree trunks and branches where some physical damage has occurred and the sap is leaking.  A wet tree trunk is usually a good spot to look.
While it is always a thrill to see the first butterflies in March, the numbers and diversity are always low.  But hang in there, it will get better soon.
Get outside and enjoy!

Harlan Ratcliff

Reference:  Dennis W. Schlicht, John C. Downey, Jeffery C. Nekola.  The Butterflies of Iowa.  2007.  The University of Iowa Press, Iowa City.

 
  Henry's elfin