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Butterfly Forecasts for Central Iowa  
  July, 2019  
  Giant swallowtailsButterfly activity is way up.  Things really start to hop in July.  Butterfly numbers are high and diversity is probably at its peak.
I had a great experience at work in late June.  I work at Camp Dodge, and there is some research going on there on monarchs.  The researchers had noted some regal fritillaries in different locations in the training areas of Camp Dodge.  I was able to go out with them and observe and verify the presence of about a half dozen regals in a couple of different locations.  They all seemed to be males.  The males come out first, and the females follow in a few weeks.  Regals require good quality prairies in order to survive.  Although the area is managed with prairie grasses and some forbs, the classic undisturbed, highly diverse prairie does not exist near to where the butterflies were found.  We had known of a couple of individual sightings in the past, but this seems to be a small population.
All of the swallowtail butterflies that we have in Iowa are possible throughout the month of July.  Look for eastern tiger swallowtails and black swallowtails in back yards throughout the state.  Giant swallowtails show up only occasionally but are very visible when they do.  If you find an area with a large population of prickly ash, which is the caterpillar host plant for giant swallowtails in Iowa, you will be treated with large numbers of the adults.  The individuals pictured to the right were in a ditch in Waubonsie State Park in the south western part of the state.  There was a large patch of purple coneflowers, where several species of butterflies were visiting.  Giant swallowtails were thick, and their pre-mating rituals were very entertaining.  The male followed the female for minutes at a time, never stopping to get a drink himself, but always flying near the female.  Both had fluttering wings.  The attentions of the male encouraged the female to move to another flower, and the male followed.  I did not witness the aftermath of the chase, but the chase definitely involved a lot of energy.
Orange sulfurs, clouded sulfurs, and cabbage whites continue to outnumber most other species of butterflies.  I have seen relatively small numbers of eastern tailed blues (although they are common enough that you will see some) this year.  Summer azures seem to be at their normal high abundance.
coral hairstreak Early July is a good time to find several hairstreaks that are never common but cannot be found at all at other times of the year.  Common milkweed and butterfly milkweed are great places to look for them.  They will stay in the same location on milkweed flowers for long periods of time.  Look for coral hairstreak, banded hairstreak, and Edwards hairstreaks in small prairie or savannah areas.  Striped hairstreak and hickory hairstreak are also possible but very rare.  You can also sometimes find these butterflies chasing each other near their host plants, which are usually trees:  cherry, oak, or hickory trees.
Juniper hairstreaks have a second generation that can be seen in July.  Gray hairstreaks use a wide variety of host plants and can be found all summer long.
Gray coppers can be found during the first couple of weeks of July, then their single generation dies out.  I did see a large number of them, near a large patch of curly dock, on the same day I saw the regal fritillaries. 
Painted ladies seem to be having a banner year.  There have been large numbers of them, as well as red admirals, mixed with a few American ladies.  Great spangled fritillaries and meadow fritillaries have been out in good numbers.  Monarch numbers are about average.  Watch for hackberry emperors in any woodland area--they will land on you if you let them.  While you are in the wooded area, watch for a little brown butterfly that stays near the ground--the little wood satyr.  It has sort of a jerky flight, and when it can it will often land on the bare ground.  If you try to photograph it you will be frustrated because it is so easily spooked and because it always seems to land with a weed or two between you and it.
Silver-spotted skippers have been pretty common this year.  I have also seen Delaware and least skippers.  For some reason, I am not seeing a lot of the other skippers that I would normally see at this time of year--little glassywing, dun, crossline, Peck's, and others.  Perhaps I have just not been out at the right time.  I expect to run across them later in the month.
The days are long but the time is short.  I need to get out in the field.
Have fun butterflying.

Harlan Ratcliff
 
  Banded hairstreaks  
  June, 2019  
  Tawny-edged skipperWe should start seeing lots of butterflies really soon.  This year has already been quite a bit better for butterflies than last year, but the excessive amounts of water might be an issue.  I have been seeing really high numbers of red admirals, and good numbers of many of the other common butterflies--painted ladies, cabbage whites, orange and clouded sulfurs, and a small number of monarchs.  I have not seen any swallowtails, although there have been some reports of sightings of black swallowtails.  Perhaps the heavy rains have slowed them down.  Or maybe I just haven't been out at the right place at the right time.
We should start seeing eastern tailed-blues and they soon will become one of the most common butterflies.  Summer azures, which are lighter blue above and are more likely to fly into the heights of the trees than eastern tailed-blues will also be out in good numbers. 
June is a great time to watch for skippers.  Some, like the silver-spotted skipper and Peck's skipper are very distinctive and not easily mistaken for something else.  Some have multiple generations in Iowa, and some have a single generation.  The common checkered skipper and the common sooty-wing are distinctive and can be found throughout most of the summer.  The tawny-edged skipper has multiple generations, but it is a little less easily identified, especially when compared to the crossline skipper, the dun skipper, and the little glassywing.  The latter three seem to be represented mostly by a single generation which comes out in late June or early July.  They can be found drinking from wet sand or mud alongside gravel roads or stream beds, or nectaring.  These butterflies can be quite difficult to identify from photographs that do not show all of the markings on both sides of the wings, but getting a good ID from a difficult-to- identify species is part of the fun.
As the season transits from spring to summer there are changes in the environment that affect not only what butterflies can be found, but also where they can be found and when they can be found.  As the days get longer the butterflies have more time to be active, so they can be found earlier in the morning and later in the evening.  Rain events change also.  Summer rains are more likely to be shorter in duration than spring rains, but to have more energy.  When it rains in the spring you might not see butterflies for the rest of the day.  With summer rains, butterflies are often out and about within an hour or less.  In fact, sometimes the best time to see lots of butterflies is soon after a thunderstorm, especially if you have access to a gravel road with good vegetation along the ditches. 
There is also a progression of flowers, some of which are magnificent attractors of butterflies.  Pale purple coneflower blooms in late May to early June in some of the better tallgrass prairies.  (The presence of pale purple coneflowers is what puts them into the "better" category.)  Purple coneflower starts its blooming a few weeks later and lasts quite a bit longer in the season.  Because of its long blooming time it seems to be more likely grown in backyard gardens than the other species.Great spangled fritillary  Both species are great for butterflies.  Other flowers to watch for are dogbane, which has a small white flower that attracts all kinds of pollinators.  Milkweeds, especially common and butterfly milkweeds are also great butterfly attractors.  It can be worth your time to check out patches of those particular flowers.
The last two weeks of June will be a good time to find hairstreaks.  There are a few species in Iowa that have a single flight that happens in late June and early July.  The best places to look for them are on common or butterfly milkweeds.  Banded, Edwards, and coral hairstreaks are common enough that you might be able to find them through extensive searching in good habitats.  Hickory and striped hairstreaks would also be possible, probably on milkweeds in savannah habitats. 
One of the larger gossamer-wing butterflies, the gray copper, can be common in wet to mesic prairies.  Look for it to be freshest in about the middle of June. 
Many of the brushfoot butterflies start showing up in June.  The northern pearly-eye can be found on the edges of woodlands and brushy trails.  The little wood satyr can be found in the same habitats.  Both are likely to rest on the bare ground in wooded areas, and can almost disappear because they are so well camouflaged.  Pearl crescents and silvery checkerspots are more conspicuous and generally will rest in more open areas.  Question mark butterflies and eastern commas can often be seen mudding.  Viceroys and red-spotted purples start to show up early in the month and can be common in certain habitats by the end of the month.  Meadow fritillaries are common some years, and not so common in others.  Look for great spangled fritillaries to be common by about the middle of the month, and they will persist most of the summer. 

Targets:

Regal Fritillaries:  Regal fritillaries are large, spectacular prairie obligate butterflies.  Typically they can only be found on good prairies that have populations of prairie violet or bird's foot violet.  On good years they can usually be found on several local prairies and are not too difficult to find, but are difficult to get close to.  But you do have to go to a special place--a good prairie--to find them.  Rolling thunder and Medora prairies in Warren County have them, as do a number of others.  You are not likely to ever see one in your back yard garden, however, unless it is close to a prairie. 

Ant flies:  I am deviating a little from the butterfly theme, here.  These are flies, mostly in the genus Microdon.  I have yet to see one in the wild, although I have seen photos.  They are syrphid flies that look sort of like bees.  The larva look like little slugs, and in fact were initially mistaken for gastropods.  The larva are predators on ants--usually the eggs or larva.  I understand that the adults typically do not fly much, and mostly just stay near the ant nests that they came from or that they will deposit eggs near.  A small number have been found in Iowa, but there should be several species.  I have no special reason for looking for them, just that I think they would be cool to find.

Get outside!

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

Targets:

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

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

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

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