|The Poweshiek Skipper Project|
|Butterfly Forecasts for
|August 16-31, 2014
Butterfly populations reach a crescendo in the last half of August and the first part of September.
Black swallowtails have three or four generations in Iowa, and often show up in numbers when the tall and bull thistles start blooming. Some will be old and ragged, and some will be dark black with brightly contrasting highlights, and have likely recently emerged. We should look for them now, but keep in mind that they have mostly been absent this year. They may or may not show up.
Fortunately, other butterflies have more common this year. Eastern tiger swallowtails have been flitting around a bit this year. In fact, the few large black butterflies I have seen recently have been black females of the eastern tiger swallowtail, and not the black swallowtails I initially thought they would be.
Orange sulfurs have been very common. You might also see the slightly smaller clouded sulfur (less common this year), and the much smaller little yellow.
If you see white butterflies they might be cabbage whites, but they are more likely to be the white form of the orange sulfur. The checkered white might also be present--while rare, they are usually easy to pick out because they are slightly larger than the other two.
Summer azures will slowly fade away, and eastern tailed-blues will continue to be common.
Early July there was a fairly good population of painted ladies. This butterfly can have large population outbreaks, and I suspect that might happen this year. Painted ladies are also migratory, and can suddenly appear where few were seen earlier.
Monarchs are present in pretty good numbers this year, which is great considering the very low numbers last year. The amazing migration of these butterflies is still at risk, however, due to changes in land use related to farming.
Pearl crescents are always common, and their numbers really pick up late in August. Also watch for silvery and gorgone checkerspots.
Red admirals have been around most of the summer, and some are getting pretty ragged. They can be found perching on trees and the ground in the early evenings. A new generation will soon emerge, and they will spend less time defending territories and more time visiting flowers.
A number of skippers can be found late in the summer--Peck's skipper and least skippers can be found at other times of the year as well, but can become pretty common late. Also watch for Delaware, tawny-edged, and common checkered skippers. Fiery skippers and sachems show up late and can be seen until late in the fall, often after the first light frost events.
This is a good time to watch for butterflies that normally live and winter to the south, but form good populations that move north. Cloudless sulfurs may occasionally be seen, as can the southern dogface and sleepy orange. We may even get strays that are not officially on the list of Iowa butterflies.
But it is also a good time just to enjoy the numbers of butterflies. There is something magical about visiting a prairie, wetland, or alfalfa field and just enjoying the large numbers of butterflies there.
But we have done much to reduce those numbers. Imagine seeing ten times what you see now, or a hundred times. An estimate of what used to be here might go as high as a thousand times what we have now.
Numbers matter. What we have lost in butterfly numbers will probably never be fully restored. But there are small things we can do to bring some of them back--planting more native plants, mowing less, spraying less. Not one big change but lots of small changes.
Enjoy the butterflies.
August 1-15, 2014
Until recently we have had a good number of butterflies. It seems the numbers have gone down a little bit, especially for this time of year. But they should bounce back soon.
It is difficult to sort out trends in butterfly populations over the short term. I have recently become involved with a project that is designed to keep information from butterfly surveys over a long period of time. E-butterfly started in Canada, and is now collecting information from the United States as well. I would encourage all of you who do butterfly surveys or even just occasionally record what you see to check the site out, sign up, and submit your own records.
Cloudless sulfurs, little yellows, American snouts, fiery skippers, and sachems do not over-winter in Iowa, and usually show up in significant numbers late in the year, so watch for them now. Red admirals continue to be common, and will continue to be common for a while. Painted ladies were quite common about a week ago and seem to have temporarily disappeared, but I expect them to come back in high numbers before the summer is through.
As is typical for this time of year, orange sulfurs seem to be the most common butterfly. Clouded sulfurs, which are slightly smaller and lighter in color from above are also common. The two species interbreed, and there are often individuals that cannot be distinguished in the field. White butterflies you see now are more likely to be a white form of one of these species than to be a cabbage white, although cabbage whites can often be locally common.
The swallowtail species seem particularly uncommon this year--I have seen a few eastern tiger swallowtails, no giant swallowtails, and only one black swallowtail. Normally, black swallowtails are fairly common and hard to miss.
Summer azures have been numerous this summer, and will continue to be for a short time. If you see a small blue butterfly, flying fairly high, it is more than likely a summer azure. The eastern tailed-blue is a similar size but a darker blue or gray above, and is more likely to fly low to the ground. Reakirt's blue is small, and not often encountered. It seems to be mostly a prairie species, and I haven't seen it enough to be able to give good advice on where to find it. I have actually run across marine blue a few times in Iowa, and it is always a treat to find.
Pearl crescent can almost always be found in prairie or old field areas, and silvery checkerspot can be found there as well, but is a little more common in the wooded areas than is the pearl. Silvery checkerspot numbers seem sort of low this year, however.
Gorgone checkerspot is rarer than the other two, but can be seen in some of Iowa's prairie areas as well.
The hackberry emperor is a very friendly butterfly of woodland clearings, and it will often land on a lucky hiker, and can be coaxed from there onto a finger for closer inspection. Numbers of this charming butterfly have been low this year as well. Less common in Iowa is the similar tawny emperor, which is browner in color and lacks the eyespot on the upper wing.
Great spangled fritillaries and regal fritillaries should still be around, but are getting old and ragged by now.
I have found many of the mid-summer skippers to be uncommon or missing this year, but have recently seen my first of the year Delaware and crossline skippers. I have yet to see a silver spotted skipper, although others have reported good numbers of them.
Monarchs are more common this year than last year, and hopefully will rebound some from their terrible scarcity last year.
Get out and enjoy the outdoors while you can. The season just flies by and missing just a week outside can mean missing one or more species for the season.
Happy butterfly watching.
July 16-31, 2014
The last part of July is a pretty good time for butterflies. A lot is happening in the butterfly world. Butterfly populations are increasing, making it more likely that you may see some rare ones. But some of the butterfly action has passed us by, or will within a few days.
I saw pretty good numbers of gray coppers and coral hairstreaks this year. Both species may be around for a few more days, but will be gone by the end of the month. Also gone will be banded, striped, Edwards, and a few of the other hairstreaks.
Some butterflies that are not normally found in Iowa form large populations in their home ranges, then enter Iowa as occasional stragglers. One such butterfly is the American snout. This is a charming little butterfly with a long nose. In Iowa they may be present in small numbers some years, and not at all in others. But in Texas they form huge populations that can become a nuisance for drivers.
Other butterflies that are common to the south and often can be seen late in the year here include the little yellow, cloudless sulfur, southern dogface, dainty sulfur, fiery skipper, and sachem. One spot I almost always find dainty sulfurs is the Lincoln Access along Saylorville reservoir. Unfortunately, that location is currently under several feet of water and probably will not be very productive for the species this year.
I recently photographed a butterfly near my house that may be new to Iowa. Initially I thought it was a field crescent, but after some discussions and considering the possibilities, it seems more likely to be a phaon crescent. Either would be new, but the known range for phaon is closer. I know that I have pearl crescent, and silvery and gorgone checkerspots on my property, and it could be an unusual specimen of any of those.
Close examination of the range maps of different species of butterflies on the BAMONA website show that there are a lot of outliers. Observations for a single species form a well defined cluster, but there are often single observations several states away from the defined location.
As frustrating as it is, I think the ultimate answer as to what butterfly I photographed may be that no one is sure. Proof would have to involve more individuals of similar coloration, and hopefully freshly emerged individuals.
Monarchs have been refreshingly common this year, and should increase in numbers over the month. A number of prairies around the state have regal fritillaries, and it is worth your time to visit one just to see that butterfly. Recently Tyler Harms spotted two regal fritillaries on Camp Dodge--the first time they have been observed there.
The most commonly seen butterfly is likely to continue to be the orange sulfur. Summer azures remain common now but should be gone soon, replaced by eastern tailed-blues. Pearl crescents can almost always be found. I see red admirals, painted ladies, and American ladies getting nectar from the hoary vervain that grows thickly along the gravel road near our home.
Except for the few I saw early in the season, I have not been seeing many skippers lately. I saw some least skippers a few weeks ago and some common checkered skippers, but many that should be common now just don't seem to be around.
As I write this I find my eyes wandering over to the photo of the regal fritillary I took a few days ago in the wet mud road adjacent to Medora Prairie. Those of you on the Iowa Prairie Network Region 6 walk this Saturday might still find my footprints (and even my elbow prints) in the mud of the road there. And the regal fritillary is one magnificently beautiful butterfly.
(Keep an eye out for byssus and two-spot skippers there as well. Maybe even a harvester if you are very lucky--watch the edges of the roads. All are very rare and would be very good finds.)
So get out and enjoy the butterflies.
July 1-15, 2014
Now is a great time to watch butterflies. If you have flowers around you might see large butterflies--eastern tiger swallowtails, giant swallowtails, or maybe great spangled fritillaries visiting those flowers. You might notice the same individual visiting the same area, at about the same time each day for several days in a row.
You might see red admirals in the evening--perching in a particular spot on the ground, or on a leaf, or on the trunk of a tree. They chase anything that flies past them--other red admirals, other butterflies, and sometimes even birds.
Walk past a puddle and you may see dozens of butterflies, drinking from the soft earth. They will be mostly males, and they segregate themselves into groups of the same species.
Butterfly numbers have been steadily increasing. While it is fun to try to find hidden butterflies when there are only a few, it is more fun to see the airspace above a flower garden filled with flying bits of color.
Orange sulfurs have been particularly common this year. Monarchs, which were largely absent from the landscape last year have been present in some numbers this year.
Which butterfly is most common can depend upon where you are. In certain prairie areas the common wood nymph will be the most common butterfly in July. Gray coppers can be very numerous in similar prairie habitats, but they are totally absent from others. Look for them now though--their population peaks in late June and they will be totally gone by the middle of July.
Iowa has several species of hairstreaks and most of them are small and rarely seen. Several of them have only one generation, and that flight is right now. If you visit a prairie or savannah area, look for butterfly milkweed. That beautiful orange-red flower is the best place to find many of the hairstreaks. But if you don't have butterfly milkweed, look on common milkweed for them as well. Hairstreaks can be spotted from a distance on common milkweed because they break up the outline of the spherical flower cluster enough to be seen. Be prepared, however, to do a lot of searching. You might have to examine a hundred common milkweeds in order to find one hairstreak.
Banded hairstreak and coral hairstreak are the most common of these rarely seen butterflies. Edward's hairstreak can be found easily sometimes as well. Count yourself very lucky if you find striped hairstreak or hickory hairstreak. Acadian hairstreak is very rare in central Iowa, although I understand it can be more common in the states to the north of us, in prairie wetlands with willows. Mike Reese, on his Wisconsin Butterflies website, recommends looking for it perched on willows in those habitats, and has found it in high numbers on swamp milkweed.
Juniper hairstreak has a brood that flies in July, but I have been frustrated in my attempts to find it then (and mostly any time I have looked for it).
Bronze copper is a pretty little butterfly that inhabits wetland areas. I recently saw a small number of them nectaring on dogbane near a small wetland.
Viceroys and red-spotted purples are out--look for them in wooded areas near creeks and rivers. I have seen a few mourning cloaks mudding on the gravel roads after rain.
Pearl crescents are common as always, as are eastern tailed-blues. Watch for the slightly larger gorgone checkerspot in prairie areas. Silvery crescents can also be found, but are more of a woodland butterfly than a prairie butterfly.
Had we not carelessly removed them from Iowa, the Poweshiek skipper would be in the middle of its flight in prairie wetlands in northern Iowa and elsewhere. We should still count ourselves lucky, though, because the magnificent regal fritillary can still be found in Iowa, and can be seen on several prairies in central Iowa.
I have seen a few fresh, very colorful painted ladies this year, and have the feeling that we may see lots of them before the summer is over. I have not yet seen any little yellows or dainty sulfurs for the year--they may yet show up, but they are common some years and almost absent other years.
Many of the small skippers should show up any day now--Delaware, dun, crossline, and Peck's skippers should become common. Recently I have only seen the least skipper and the common checkered skipper. I have yet to see a silver-spotted skipper--they have been quite common some years, but were totally absent last year. Hopefully their numbers will bounce back.
Iowa has thousands of miles of gravel roads. Most are a fairly dusty limestone. We also have some minimum maintenance dirt roads. If you go out early in the morning when the dew is just getting off of the plants, or after a warm summer rain, you will find lots of butterflies getting moisture from the wet dirt. Look especially along the edge of the road where the vegetation meets the road. Areas with good adjacent habitat are best--go for stretches of road near rivers or creeks, or near some of the wild areas. Dirt roads can be great, but they are usually better to drive than to walk--it can be easy to get stuck out there. Areas near railroads can have some small prairie remnants which can be quite productive.
So get out and watch the butterflies. You will be glad you did.
June 16-30, 2014
As the weather heats up in the last half of June, so does the butterfly action. If you get out in the natural areas around Iowa, you may see one or two butterflies that are new for the season each day. And the total numbers start to pick up as well. If for some reason you can't find butterflies, there are plenty of other interesting creatures out. Dragonflies and damselflies, some moths, periodic cicadas, bees, and even some large flies can be quite beautiful and entertaining to watch.
The black swallowtail and the eastern tiger swallowtail should be fairly easy to find all over Iowa. The giant swallowtail is large and easy to see when it is around but it is not always common. You probably have to go the extreme southeastern or southwestern corners of Iowa to find the zebra swallowtail. Spicebush and pipevine swallowtails are rare in Iowa but more common in states to the south.
Cabbage whites, clouded sulfurs, and orange sulfurs may be the most common butterflies seen. They all have multiple broods and the numbers build up over the summer.
Watch for little yellows near areas where partridge pea is found. Cloudless sulfurs, dainty sulfurs, and checkered whites can all start showing up, but will probably not be too common.
Summer azures will be the most common blue butterflies initially, and their numbers will be overtaken by eastern tailed-blues by the end of June or the first part of July.
Some of the small hairstreak butterflies make their only appearance of the year now. Watch for banded hairstreak, Edward's hairstreak, striped hairstreak, and coral hairstreak. Common and butterfly milkweeds are great places to find these butterflies, as they seem to be very much attracted to them and will stay on the flowers for long periods of time. Acadian hairstreak is likely to be found in wet areas, and often perches on willows.
Pearl crescent will be common and quite active in most areas. Silvery checkerspot is found all over as well, but is more likely to be found in wooded areas than in prairie areas.
Gorgone checkerspot might be seen mixed in with the pearl crescents. They are generally slightly larger and you should be able to notice them from a distance although you might need to get close and see the undersurface of the wings to get a positive ID.
Great spangled fritillaries are large and conspicuous and are generally common enough to be easily seen. In my experience, meadow fritillaries and northern pearly-eyes can be quite common in some years and very rare in others. You may see many or none at all.
Monarchs have been more common this year than last, at least in my unscientific opinion. They don't show up in high enough numbers to be significant on my surveys, at least in this early part of the season.
Red admirals maintain a presence all summer long, and can often be seen in the early evening, perching in conspicuous positions and chasing other butterflies that come too close.
Eastern commas, question mark butterflies, buckeyes, and painted ladies should be present now. Mourning cloaks can be seen all summer long, but are usually less noticeable now than early spring, when they are the only butterfly flying.
Many of the small skippers will be flying in the last part of June. Before it was extirpated from Iowa, Poweshiek skippers were present in fairly high numbers on some of the undegraded prairies in northern Iowa. But it's gone now.
You should be able to find the least skipper, Delaware skipper, dun skipper, common checkered skipper, and common sootywing.
The silver-spotted skipper should be showing up soon as well,
The start of summer is a great time to watch butterflies in Iowa. But it also seems to be a busy time for other activities. Make sure you are not shorting yourself. Find some time to look for butterflies. You will be glad you did.
|June 1-15, 2014
The first part of June always seems like it should be better than it turns out to be. The diversity is higher than earlier in the season, but the numbers usually drop off a little. I am not really sure why, but I think it is that of the butterflies that have more than one generation per season the first flight is dying off and the next flight will happen later. It could also be an artifact of where I watch butterflies. I take a walk at work and count butterflies as I do. But the area is turf grass. Dandelions are sprayed in late May or early June. Do the pesticides kill off enough butterflies to affect my surveys? I don't know. Other areas that are not sprayed for dandelions can be sparse this time of year as well.
But the numbers will slowly build up over the summer, barring extremes of weather.
One lovely butterfly that should be showing up soon is the little wood satyr. It has a delicate, dainty flight--you will see it in among the weeds, and it seldom flies in the open. It can be found on open wooded areas. Although the caterpillar host plants seem to be grasses, the little wood-satyr can be found pretty much anywhere you can find poison ivy.
Hackberry emperors should make an appearance. They also like wooded areas. These charming little butterflies are far from shy, and in my mind are the most likely of any butterfly to land on people.
I have seen a few monarchs already this summer. Monarchs had record low numbers in the Mexican forests where they spend the winter this year. The numbers are likely to rebound if weather conditions are right. However, a seasonal increase in numbers will not result in a permanent recovery. The reduction, by one third, in suitable monarch habitat that has occurred since 1993 will continue to take its toll. The phenomenon of massive numbers of monarchs migrating across North America is still at risk.
We should be seeing the monarch mimic, the viceroy, in numbers in early June. The closely related red spotted purple (or red spotted admiral as the North American Butterfly Association calls it) should also make an appearance. Look for both in wooded areas.
You should be able to find pearl crescents and silvery checkerspots. Meadow fritillary should be flying as well.
Mourning cloaks can be found in small numbers all summer long, so don't be surprised to see them now. Red admirals mostly make their presence known late in the day, when the sun is almost setting. Then they can be found soaking in the last rays of the sun in back yards all over Iowa.
Watch for common buckeyes in areas that have a mix of trees and closely cropped grass. They can be quite common and active.
Orange sulfurs and clouded sulfurs are among the most common butterflies of Iowa. You will see them occasionally in the first of June, but they will be much less common than they are at other times of the season. Cabbage whites can also be seen.
The eastern tailed-blue is the most commonly seen small butterfly. You may also see the summer azure, especially towards the middle of the month.
Some of the skippers will make appearances in some numbers. The silver-spotted skipper is the largest of these and is always a delight to find. You might also see the common checkered skipper. Hobomok skipper and Peck's skippers are brightly colored--light brown with patches of yellow. While they are on the smallish side they are showy and perky and fun to watch.
If you walk along a pond or creek bed with stands of tall grasses you might find least skippers in fairly large numbers. This is probably our smallest butterfly, but if you learn to look for the bright white belly it is very easy to identify. It has a less-heavy body than some of the similar-looking small brown skippers.
So get out if you can. Summer is just starting but it passes by so fast. Don't miss out on the butterflies.
|May 16-31, 2014
The days are heating up and getting longer. More flowers are blooming than were a few short weeks ago. And the butterflies that can be seen are getting more numerous and varied.
Changes in the weather are favorable for butterfly watching as well. In the early spring, rains tend to be cool and last all days. If it rains you are not likely to see a butterfly all day. In the late spring we get thunderstorms, and after it rains the sun comes out and it warms up. Sometimes those warm days an hour or two after a thunderstorm are the best days for viewing butterflies.
All of Iowa's swallowtails can be seen in late May. Black swallowtails can be common in old field areas. Eastern tiger swallowtails are found in areas that are more wooded. Giant swallowtails are not so common, but are quite large and when present will be easily noticed. Zebra swallowtails are not usually found in central Iowa, but can be found in occasionally in extreme southwestern and extreme southeastern Iowa. Pipevine and spicebush swallowtails are occasional strays and could possibly be seen, but are unlikely.
Cabbage whites can be very numerous. The flight period for Olympia marbles will be over soon--I have to confess that while I have hunted for this butterfly I have not successfully located any. Clouded sulfurs and orange sulfurs will be present in high numbers. Those two species are similar and can interbreed and produce hybrids. Of the two, I have been seeing mostly orange sulfurs lately.
Eastern tailed-blues should start showing up in fairly large numbers soon--so far, I have only seen one, and it was a very battered female. I usually see a number of fresh males before I start seeing females. Males are blue above, usually a deep shade of blue, and females are gray. I have previously discussed the azures. If you see an azure during this time period it could be an old spring azure, or it could be an early summer azure. The species "splitters" have identified Appalachian azure as emerging between the two previously named species, and as being slightly larger than the others. It is not known to occur in Iowa, but should be looked for where black cohosh occurs. You might be able to see a gray hairstreak in late May. White M hairstreaks are very rare in Iowa, but could occur during this timeframe as well.
Bronze copper is never very common, but it is such a colorful butterfly that it will probably be noticed anywhere it occurs. Look for it around open wetland areas.
Small butterflies you might see now include the pearly crescent and the meadow fritillary. The painted lady, American lady, red admiral, and buckeye all may be present. Red spotted purples and viceroys should emerge by the last week of May. Monarchs may make their first appearances (in fact, I have seen two already).
Several of the duskywing skippers can show up in late May, including Juvenal's, Horaces, and the wild indigo. Common checkered skippers and common sootywings should be around by the last of the month. Peck's skipper, Hobomok skipper, and the least skipper will show up as well.
It is common to see some of the butterflies doing courtship dances now. Typically they consist of two (or more) butterflies chasing each other in circling flight. These courtship flights can cover vast distances and often you won't see them land.
Red admirals perch on sunny spots on tree trunks, buildings, or even on the ground, then fly out and chase anything that moves past them. I have heard of people luring them from their perches by waving bits of colored paper past them on a fishing line but I haven't tried it myself.
Pearl crescents can often be found in pairs or trios, displaying to each other while obtaining nectar from a flower. The female is the largest, and the male(s) are smaller.
But the season moves along at a rapid pace. Get outside and enjoy it.
May 1-15, 2014
Butterflies have been making appearances in Iowa recently, although not in large numbers. We have also had stretches of several rainy days in a row, keeping the butterflies hidden.
The season progresses rapidly with some butterflies flying only during a short window of time. Henry's elfin is found in a few counties in southern Iowa, mostly near the caterpillar host plant, redbud. Ryan Rasmussen reported seeing a dozen of these butterflies in Davis County near Lake Wapello and Soap Creek. It may be possible to find them within the next week or so in other locations, but look for them soon because the flight window is not all that long.
Olympia marbles also might be found within the next week or two, mostly in the Loess Hills area. They also have a short flight window, so look for them soon.
Some of the more common butterflies will show up soon. Many have one or more generations per summer, so the flight window is not so critical. I have seen only one clouded sulfur so far but they will appear in good numbers soon. A number of red admirals have been reported and will continue to be present for a while. The individuals I have seen so far have been noticeably smaller than what I usually see, especially later in the year. Cabbage whites, eastern tiger swallowtails, and black swallowtails should make their appearance in the first part of May.
Eastern commas and mourning cloaks should still be around in small numbers. The question mark is similar to the eastern comma, but a little larger and with longer tails. It typically shows up later than the eastern comma, although it is thought to have a similar life cycle--spending the winter as an adult. Some sources suggest that the question mark is migratory instead (or in addition). In any event, it is a welcome addition to the spring butterflies.
Painted ladies and American ladies often show up in early May. Bronze coppers and American coppers can be found now as well.
Spring azures can still be found for a little while longer, and eastern tailed-blues will start making their first appearances.
One of my favorite skippers is a flying fireplug of a butterfly--the silver-spotted skipper. Many years they are very common, but I don't think I saw any last year. I am hoping they show up in larger numbers this year.
Juniper hairstreaks have two generations per year in Iowa. I have not seen them often, but when I have it has been in either late April or early May, and not the second, late July generation.
In an earlier post I mentioned some citizen science websites which can be used to determine some of the butterflies to look for. One I failed to mention is Dr. Royce Bitzer's red admiral and painted lady migration site. It tracks migrations of the four North American Vanessa species.
There is also a way to use the Bugguide website to find recent sightings (or at least recent submissions). Go to the guide tab, then find the butterflies (hexapods, insects, Lepidoptera). Click on either the true butterflies (Papilionidae) or the skippers (Hesperiodae), and click on the images tab. You will see a "recent images" link. Click on it, and you will see all of the recent submissions for the butterflies.
If you wanted, you could use the same process to find the recent photos by species, so you could track all of the recent sightings of monarchs or red admirals, for example. The butterfly photos are shown in the order they were submitted--not necessarily the date the photo was taken. With a popular enough species some pretty good phenology information could be teased out of the records.
Or, you could get outside and look for real butterflies instead--teasing phenology from websites seems like more of a winter project. Chasing live butterflies a lot more fun.
April 16-30, 2014
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 occurred 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, it 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.
|April 1-15, 2014
While 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. Others 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.
|March 1-31, 2014|
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?