HomeOarisma PoweshiekThe History of the ButterflyIowa's Biological Diversity  
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Butterfly Forecasts for Central Iowa  
  October, 2017 to end of the year  
  sachemSummer is over, winter is coming, and another butterfly season is coming to a close.  Did we "waste" enough time watching the butterflies?  If not, maybe we need to hurry up and get outside.
The good news is that there should still be a few prime butterfly observing days left, if we can find the time to enjoy them.  The bad news is that there are only a few.  The butterfly season may be over as early as the middle of October, or it could last well into November.  After that we will have to wait until the winter is over to see them again.
On a warm day before the first frost, there are still quite a few butterflies that might be seen.  Black, giant, or tiger swallowtails are possible, but very unlikely.  You should be able to see cabbage whites, orange sulfurs, or clouded sulfurs.  If you look closely, you might see eastern tailed-blues.  Gray hairstreaks are possible late into the year.  You might see ragged pearl crescents or silvery checkerspots.  Some of the migratory brushfoot butterflies can be seen--common buckeyes, red admirals, and American ladies.  I am not sure of the status of the monarch migration--I never saw a huge accumulation of them, although I did see some reports of large clusters.  I continue to see a few every day, though, flying at tree level.  My impression is that there has not been a weather event yet this year to accelerate the migration.  They are present, and in fairly good numbers, but they are not as concentrated as we see them in some years.  That is just an impression though--someone may have data that shows me right or wrong in that assessment.
We had a very impressive migration and irruption of painted ladies during the first week of September.  It was easily larger than any migration I have seen since at least 2003.  For a while any flower you could find was covered with painted ladies.  Then the numbers went down, and slowly picked up again.  We will not see the numbers we saw in early September, but I expect there will continue to be painted ladies in our lawns and gardens until we get the first frost.
Most years there are pretty good numbers of some of the brushfoot butterflies that over-winter as adults--eastern and gray commas and mourning cloaks.  This year it seems that there are not as many as normal, especially on the fallen apples where I usually find them.  I still see a few, but I think the population is down.  That might have an impact on when we first see butterflies in the spring, and the numbers that we see then.  Of course, the winter weather will also have an impact.
Some of the skippers can continue to be seen until late in the year.  With their high populations, I think we will see silver-spotted skippers for a couple more weeks.  We will see sachems, Peck's skippers, tawny-edged skippers, fiery skippers, and maybe a few others until we get a killing frost.
orange sulfurButterfly numbers can fluctuate wildly from year to year.  This year was on the low end of the spectrum.  The numbers I saw on my surveys were half or less of what I see on average.  What was especially noticeable was the very low numbers of normally common species.  Clouded sulfurs, orange sulfurs, and eastern tailed-blues were sometimes completely absent, although they seem to have picked up now--very late in the season for them.  Most years those three species account for over half of my sightings, but this year they accounted for less than a third.  Painted ladies seldom exceed five percent of my surveyed butterflies, and sometimes are only a fraction of a percent.  This year, well over half of the butterflies I counted were painted ladies.
We also had good numbers of red admirals early in the summer.  We saw some of the southern migrants, like goatweed leafwing, white M hairstreaks, and zabulon skippers early in the year.  I thought that might translate into high numbers late in the year, but that prediction did not pan out.
If you want to see lots of butterflies and don't mind traveling outside of the state, you might want to go to the Texas Butterfly Festival in the early part of November.  I probably won't make it this year, but I have made it in the past and plan to go again.  When I went a few years ago there were so many butterflies that it took my breath away.  The Mission, Texas area is on a natural migration pathway for butterflies (and birds) and the overwhelming numbers and diversity make the area someplace that should be on everyone's bucket list.  There are construction projects in the area that threaten to damage the area ecologically, so sooner might be better if you plan to visit.
If you find yourself depressed by the lack of butterflies in the middle of the winter in Iowa, you might also consider a visit to Reiman Gardens in Ames.  A walk through the butterfly wing really can lift the spirits.

So get out now and watch the butterflies. 

Harlan Ratcliff
 
  henry' elfin  
  September, 2017  
  Painted lady The butterfly season is rapidly slipping away.  Summer always seems so slow to arrive and so fast to leave. 
Often September will find goldenrods and asters full of bright yellow and orange-yellow sulfur butterflies.  Not this year, though.  A few orange sulfurs can be found, but the numbers are greatly reduced when compared to more "normal" years.  Still, there are plenty of other butterflies when the weather cooperates.  On a cool day with clouds you might not see any, but when the sun pops from behind the clouds suddenly the flowers will be full.  Butterflies that can be seen in good numbers include several of the skippers.  Silver-spotted skippers are unusually common this year, but you can also see Peck's, tawny-edge, and fiery skipper.  Sachems are the largest of the grass skippers--not as large as the silver-spotted, but larger than most other skippers you will see.
I have not been fortunate enough to find Leonard's skipper yet, but I think I know how to find it.  As near as I have been able to figure out you either have to go to the western part of the state (at least a 2 hour drive) or to the north-east part of the state (maybe four hours for me) to some hilly prairie country.  Then you walk five miles or so, inspecting all of the liatris that you find.  If you don't find any, walk another few miles until you either find them or give up and try another day.  I will find them sometime, but it may take a while.  (I am sorry if my frustration shows through here.  They are on my bucket list).
Monarch numbers have been good around here this year, and by the middle of September we should start seeing some of them migrate.  If you are lucky you might find a communal roost of migrating butterflies.  I have seen them in some of our walnut trees in past years.  A roost is always a thrill to find. 
Other butterflies we see here have two-way migrations as well, most notably common buckeyes and the Vanessa species (red admirals, American and painted ladies).  Usually they are widely dispersed and their movements are not especially noticeable unless they are present in large numbers.  We might see good numbers this year, however, especially of painted ladies which seem to be common right now.
We will continue to see large swallowtails throughout the month.  Eastern tiger swallowtails have been especially common, but giant swallowtails have been present in good numbers as well.  Black swallowtails have been a little less numerous than some years, but can still be seen.
Eastern tailed-blues are present in small numbers this year.  Gray hairstreaks can often be seen among the prairie flowers in September, so watch for them.  There have also been some unusual sightings of melissa blues in central Iowa this year.  Any small blue that you see should be examined closely if possible because it could be something surprising.little yellows
I have seen a few little yellows, but as with the orange and clouded sulfurs their numbers seem below normal.  I have not recorded a dainty sulfur yet, but photos have been posted on the Iowa Butterflies Facebook page.  Where they are present they are likely to be common.  Cabbage whites seem to be present at normal levels.
We have an apple tree and a crab apple tree that suddenly seems to be bearing normal sized apples from a few limbs.  If the apples are allowed to remain after they have fallen they will often attract butterflies.  Sometimes damaged apples that remain on the tree attract butterflies as well.  I have seen red-spotted purples, viceroys, hackberry emperors, eastern commas, red admirals, and question marks, all on fallen or hanging rotten apples.  The apples attract a variety of other insects as well, including flies, bees, and wasps.
The butterfly season should easily last through the end of September.  Depending on the weather it might be done soon into October.  Sometimes it will last well into November.  You never know.
So get outside and enjoy it while you can. Once the cold weather hits it will be a long time before the butterflies come out again.

Harlan Ratcliff
 
  Henry's elfin  
  August, 2017  
  gray hairstreakAugust usually sees a general increase in the numbers of butterflies, and this year will be no exception.  Although a couple of the normally very common species are experiencing lower than normal numbers, most seem to be doing well.  Orange sulfurs would normally have been filling the air over the last few weeks, but they are just now starting to put in an appearance.  They can be easily found, but the population is very low compared to most years.  Eastern tailed-blues, also very common most years, have very low numbers this year.
Swallowtails can put on quite a show this time of year.  Typically they can live for several weeks in the summer, and you will see some individuals that are quite ragged.  Others will look very fresh.  Garden flowers are quite attractive to them, as are tall thistles.  Eastern tiger swallowtails often make several visits per day to the same flowers--their visits can sometimes be about the same time each day.  Giant swallowtails are a little less common, although they are hard to miss when they do show up.  Black swallowtails can often be seen over prairies and old fields.  To see zebra swallowtails you need to go to Waubonsie State Park or Shimek State Forest, in the southwestern or southeastern corners of the state.
Most hairstreaks are gone for the season, but not gray hairstreaks.  They can be seen from now until about the end of the summer.  They are not too common, but can be easy to spot as they are larger than most blue butterflies.  Summer azures and eastern tailed-blues will make up the bulk of the small blue butterflies.
August often brings an influx of butterflies that spend the winter in states to the south of here.  Many have been previously seen much earlier than expected here.  Southern dogface, goatweed leafwing, and Reakirt's blue have all been reported and are usually quite rare here.  Little yellow and dainty sulfurs are southern imports that can often be found in some numbers in Iowa.  Look for little yellow anywhere partridge pea is found. 
 Sleepy orange and cloudless sulfur are less common in Iowa, but look for them in the same habitats.
Great spangled fritillaries are common and visit larger flowers.  Regal fritillaries should still be found in good prairie locations for most of the month.  Variegated fritillaries are not very common, but I have seen a couple recently and more may show up for a short time during August.
Monarch butterflies seem to be doing fairly well, at least around here this year.  I don't know how the northern populations that will migrate through here later in the year are faring, however.
giant swallowtailRed admirals will be seen in back yards all over the state.  They are often active right before sunset, setting up territories and chasing other butterflies.  Also watch for painted ladies.  Both are capable of having small population explosions (called irruptions) and could be present in really high numbers.
Pearl crescents and silvery checkerspots can be found on many of the smaller flowers that bloom this time of year.  Also keep an eye out for the gorgone checkerspot, which is much less common, but distinctive when the under surface of the wings can be seen.
Watch for the American snout butterfly in August, as well.  As suggested by the name, this butterfly appears to have a big nose--it is quite distinctive.  Although this butterfly can reach huge populations in Texas, usually it only encountered as single individuals in Iowa.
Skippers can become fairly common this month.  Silver-spotted skippers will be seen visiting thistles throughout the month, but their numbers fade in the second half of the month.  Common checkered skippers will start to become more common as the month goes on. Peck's skipper and tawny-edged skippers are found here all summer long but can become quite numerous late in the season. 
A fairly large skipper, the sachem, is a southern import that becomes more and more common as the season goes on.  Fiery skipper is another southern import, slightly smaller and a bright yellowish-orange color.  If you see a male fiery skipper in the typical jet-fighter pose that grass skippers often use you will get a good idea how it got its common name.  The upper surface of its wings have markings that resemble a flame.
Summer is rapidly slipping by, and with it the butterfly season.  Get outside and enjoy the butterflies while you can.
         
                                                   Harlan Ratcliff

 
  Henry's elfin  
  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