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  Butterfly Forecasts for Central Iowa
April 16-30, 2014
pearl crescent
The arrival of spring has been slow this year.  It is not just the butterflies--the wildflowers are also a few weeks later than their usual blooming times.  The first reports of butterflies seen this year occured on March 30.  A number of sightings have been reported since then, and most have been either mourning cloaks or eastern commas--butterflies which spend the winter in the adult stage.
There has been one reported sighting of a migratory butterfly--a red admiral.  There have also been reports of a couple of sightings of migratory dragonflies--the common green darner, Anax junius, and the variegated meadowhawk, Sympetrum corruptum.
Weather has a big effect on butterfly numbers in the spring.  As the leaves start to pop on the trees and the woodland  ephemeral wildflowers start to bloom we will see a sudden increase in butterflies, particularly in those that spend the winter in some stage other than the adult.  We will see cabbage whites and black swallowtails first, followed by clouded sulfurs and pearl crescents.  We may also see a tiny blue butterfly that flies high in the trees, the spring azure.
There is a controversy among lepidopterists regarding the butterflies in the genus Celastrina, the azures.  It is explained pretty well on this link to bugguide.  Taxonomists generally fall into two groups (taxa?)--the lumpers and the splitters.  When there are small differences between populations of particular critters, some lump them together and some split them.  Dr. David Wright makes the argument that there at least eight species in the genus and that through most of the eastern range there are several species that appear to be similar but that can be differentiated on the basis of phenology and subtle differences in size, scale arrangement, and caterpillar host plants.  The idea that there is a "spring" azure (C. ladon) and a "summer" azure (C. neglecta) and they are both found in Iowa seems to not be controversial.  There may be a question about whether or not there is a spring brood of C. neglecta, and how they can be differentiated from C. ladon.  Of course, there is also the question about whether or not the differences are enough to rise to the species level, or if they can be considered subspecies.
Two of the eight species, C. neglectamajor, the Appalachian azure, and C. serotina, the cherry gall azure are distinguished in part by the caterpillar host plants.  Neither is found in Iowa, according to the published ranges.  However, clouded sulfurit seems that it would be reasonable to look for them here.  The host plant of the Applachian azure is given as black cohosh, and the host plant of the cherry gall azure is given as galls on the surface of black cherry leaves. 
The caterpillars of these butterflies are known to be associated with ants--there could be some unobserved aspect of the biology of these butterflies that may explain some of the differences.   Understanding the entire life cycle of the different types will shed more light on whether or not they are actually separate species and could yield some surprises.
So make careful observations and inspect any potential host plants.
There are some butterflies that are rarely seen in central Iowa, but more common in either the western or southern parts of the state that usually show up in the last two weeks of April.  Given the late spring this year, I wouldn't expect them until the very last few days of this month or the first one or two weeks of May.  The Oympia marble is mostly found along the western-most tier of counties in Iowa and the extreme northeast.  It is reported to be a very active butterfly, making it difficult to photograph.
The first brood of juniper hairstreaks can normally be found towards the end of April, with a second brood happening in July and August.  I have been fortunate enough to find it a few times, but it is a very beautiful butterfly and well worth the effort.  I have looked for this butterfly unsuccessfully much more often than I have been able to find it.
Henry's elfin can be found on its host plant, the redbud, usually in late April but probably in early May this year.

Mother Nature taunts and teases us with spring.  She promises us flowers and butterflies but squeezes in one or two or maybe three more cold rainy days between us and the butterflies.  She tests our patience.  But if we become too patient she closes that window.  If you miss the Henry’s elfins or the Olympia marbles in April or May you have missed them for the year.  And the taunting continues next year.

So get out there—embrace the challenge.  Feel the sun on your face.  Smell the damp earth.  And watch for those butterflies.

Harlan Ratcliff
  coral hairstreak  
  April 1-15, 2014
Cabbage white butterflyWhile we tolerate a cooler than normal spring, complete with polar vortexes and other weather phenomena that we don't normally hear about, we look for the signs of spring that we know are coming. 
There are at least three valuable internet resources available that can give us a clue as to what butterflies can be seen.  The North American Butterfly Association has a Recent Sightings page.  An eastern comma and five mourning cloaks were seen in Bronx County, New York on March 22, 2014.  A cabbage white was seen in Maryland on the same day.  Lots of butterflies were seen in California and Texas, but the New York and Maryland butterflies are closer to what we will see.  The Butterflies and Moths of North America website also has a recently verified sightings page, with a location map showing the most recent ones.  This one is a little trickier.  Although the maps are clear, the table shows moth and butterfly photographs that are "recently verified"--not necessiarily recently seen.  But you can weed out the old photographs.  By looking at that site, I can tell that an Eastern comma was seen on March 21, 2014 in Cocke Co., TN, and a question mark and morning cloak were seen in Green County, Missouri on March 15th.  That list continuously replaces existing sightings with new, so the old ones drop off.  And of course, there is the Wisconsin Butterflies website--specific to that state, but it can give us a pretty good idea of what to look for.  This website shows historic sightings, so gives a pretty good phenological record. 
People are good at reporting first sightings on the Iowa insects listserv as well.  As of March 29th, no one has reported seeing a wild adult butterfly in Iowa yet this year.  The 30th is predicted to be warm and sunny, with highs around 70, so it may happen then. 
The first butterflies that will be seen will be those that spend the winter in the adult stage in Iowa.  They include the morning cloak and the eastern comma, which are the two most common members of the group here.  red admiral butterflyOthers that are less common may also be encountered, including the gray comma, Milbert's and compton tortoiseshell, and the question mark butterfly.  The question mark butterfly typically shows up a little later than the others and may also be migratory.
Butterflies that spend the winter in some stage other than the adult stage, and have a tendency to show up early include the cabbage white, shown above and to the right, the spring azure, and the black swallowtail.  I would be surprised to see any of them before the middle of April, however.
Migratory butterflies like the red admiral shown to the left, may show up following a thunderstorm.  Others in this group include the painted lady and the common buckeye.
A recent conversation on the Iowa Insects listserv mentioned two butterflies that have not been recorded in Iowa, but because of their secretive habits may possibly be found here.  They are the yucca giant skipper and Strecker's giant skipper.  If it is found here, the yucca giant skipper will likely be found flying between the first of April and the middle of May.  Strecker's giant skipper would be found about a month later.  Adults of the species do not feed, and the life span of the adult is not very long.
It might be easier to locate evidence of the larval stage of these butterflies than to locate the adults.  The larval hosts are various species of yucca, and the caterpillars burrow down into the stems of those plants.  A very entertaining video of a lepidopterist locating the larva of a giant skipper can be found here.  Please note that I am not recommending that anyone use the procedure Dr. Warren is using here in Iowa--yucca plants are rarer in Iowa than they are in other locations, and if the butterfly is found here it is also likely rare.  But the larval nest and the feeding tube might be possible to find.  And if you do find it, let somebody know.  It would be great to add another butterfly to Iowa's list.
So get outside and enjoy the spring weather.  Watch for emerging butterflies.  Listen to the birds and the frogs.  Get mud on your shoes.
Harlan Ratcliff
  Coral hairstreak  
  March 1-31, 2014  
  March marks the beginning of the butterfly season in Iowa.  As we all attempt to recover from a winter that seems colder and gloomier than it should have, we look for any sign that winter is past and spring or even summer is here.
We look for the two or three species of flower that are the first to bloom--hepatica, snow trillium, maybe a few others.  The two most common early butterflies are the mourning cloak and the eastern comma.  Both are fairly large, and spend the winter in the adult stage, wedged into some small crack in the bark of a tree or under the leaf litter on the ground.  There are some others we might find--the gray comma and Milbert's tortoiseshell are found in this area, but are considerably less common than the other two.  The question mark butterfly might show up as well, but seems to be a little later than the others.
Early spring butterflies act differently than the butterflies that show up later in the year.  You won't see them on flowers--the few flowers that are around are not really butterfly flowers.  You will find the spring butterflies basking high up in the trees or near sap-oozing wounds in the branches.
Early in spring the weather has a bigger impact on butterfly numbers than it does later in the year.  What we need for butterflies is intense sunshine and a certain amount of heat.  But it does not have to be that much heat.  Mourning cloaks will show up when the temperatures are in the fifties as long as it is nice and sunny.  There can even be a significant amount of snow still on the ground--the sun just has to heat up the butterfly.
But there will be many days when you have no chance of seeing a butterfly.
Late in March, if the weather cooperates, you might see some of the butterflies that spend the winter in the pupa stage or some that migrate.  Cabbage whites, black swallowtails, summer azures, and red admirals all are possible in late March.  But not likely, unfortunately.  You probably have to wait for April for them.
But enjoy the other signs of spring--the birds and frogs singing, the bits of warm weather, and the earliest of flowers.  Mosses send up new stalks--the sporophyte stage.  Several species of flies gather in beams of sunlight, forming temporary leks.  New life is beginning, and the best is yet to come.

Good bye winter.

Welcome spring.  What took you so long?

Harlan Ratcliff