|The Poweshiek Skipper Project|
|Butterfly Forecasts for Central Iowa|
May 16-31, 2013
This spring has been unusual. I can remember several times when we have had frost in Iowa in the month of May, but I can't remember getting significant amounts of snow in May before this year. And I'm kind of an old guy.
Snow is not really good for viewing the butterflies--at least for most of them. I did notice that on the Wisconsin Butterflies site, Scott Swengel reported seeing three Compton tortoiseshells when the air temperature was around 50 degrees or slightly lower, and there was an average of eight inches of snow on the ground. Our snow went along with cooler temperatures and precipitation--not good for butterfly watching.
It seems to me that if you were to graph the numbers of butterflies over the season, most years would show two peaks--one that starts as early as March and then peaks in late May or early June, then another peak starting in mid to late June and going the rest of the summer. That is not a hard and fast rule--weather patterns have a great effect on the numbers, but it seems to hold true most years. This year I think we are still on the early, uphill part of that first peak. We are still seeing mostly the early spring butterflies--mourning cloaks, eastern commas, cabbage whites, red admirals, American ladies, and black swallowtails. We are starting to see some that typically come out a little later--pearly crescents and eastern tailed-blues (like the butterfly shown to the left), for example. The numbers that have been seen are still very low, but I think they will pick up fairly well by the end of this week (the week of May 12) if the weather forecast holds. By the end of the month, hopefully, we will be seeing a lot of butterflies, including some of the butterflies that are more typical of summer than early spring. I am (finally) starting to see a few myself.
One of the butterflies that shows for the first time in late May also happens to be one of my favorites. It is a large, fat skipper that typically lands on the edge of a flower and sticks its proboscis over the flower to get nectar. It is the lovely silver-spotted skipper, as shown below and to the right.
Clouded sulfurs should be showing up any day now--they are a fairly common species, and can constitute a large percentage of the total number of butterflies seen at any one time. Orange sulfurs will be showing up as well--in my experience they come out a little later than the clouded. Eastern tiger swallowtails and giant swallowtails should be present in small numbers, the they are so showy and conspicious that if one is present you will be likely to see it. Great spangled fritillaries are also large, showy butterflies, and I would expect to see them by the last week of May at least, and possibly sooner.
Monarchs should start showing up by the last couple of weeks of May, and buckeyes as well.
One of the treats of this time of year is the appearance of some of the smaller skippers. The hobomok skipper can be found in domestic gardens, as can Peck's skipper, the tawney-edged, and the Delaware skippers. The common sootywing and the common checkered skipper are not rare, and both can show up now.
It is a lot of fun to walk out in the wild when butterflies are everywhere. Sometimes they are not so common, however. Then you have to search a little more. But when you do see the butterflies, the effort is worth it.
Be sure to get outside. You will be glad you did.
Until next time...
May 1-15, 2013
The seasons seem to be a couple of weeks later than normal this year. Maybe if I just repeat the butterfly forecast from last time it will be pretty close. But I really hate to do that.
As of April 29 of this year I have seen exactly zero butterflies. Nada. Zilch point nothing. And that is unusual for any year.
But we haven't exactly been having days that are good for butterflies. And other things have come up for me in the good days that we have had. The closest I came to seeing a butterfly was that I found the wing of a red admiral on a woodland floor--it looked to be fresh enough to be from this year, but how can you be sure?
There have been reports from others who have seen some butterflies, although the reports have proven to be less than what would normally be seen this time of year. The most I have seen reported was seven species and 24 individuals by Thomas Jantscher and Frank Olsen. They saw a Henry's elfin and a Juvenal's duskywing, in addition to the more common black swallowtails, red admirals, spring azures, cabbage whites, and mourning cloaks. Twenty four butterflies might seem like a lot, but it took them five and a half hours to see them. That is an average of about one butterfly every 15 minutes. That is a pretty slow rate for this time of year, especially for two of the top butterfliers in Iowa.
The butterflies are pretty sparse now because of the cool wet weather we have had, but the drought of last year might have reduced this year's crop as well.
Butterflies are pretty resiliant, and their numbers should rebound pretty well this season, given good weather, but it may take a while. Of course, if you look at the land use patterns in Iowa, it becomes apparent that the numbers we are accustomed to seeing are only a tiny fraction of what we would see if the vegetation patterns prior to European settlement persisted.
In addition to the seven species mentioned, we should see painted and American ladies, eastern tiger swallowtails, and eastern commas.
The clouded and orange sulfurs should start showing up--in my experience, the clouded sulfur appears before the orange. We should be seeing pearl crescents soon as well.
The most common of our blue butterflies, the eastern tailed-blue, will have a generation emerge. Usually they are not particularly common in the spring. Males, with their dark blue upper wings will appear first, followed within a day or two by the females with their brown upper wings. Then, depending on the weather, eastern tailed blues will disappear for a while and reemerge in significant numbers later in the summer.
It is still a little early for many of the small skippers, although you might see the dark black common sooty wing flitting around your yard. If the color black can be thought of as brilliant, it surely is on this butterfly. Though small, the black coupled with the white spots make this a very beautiful insect.
Other skippers that you might see include the tawney edge skipper and Peck's skipper.
Viceroys and red spotted purples can often be seen in the first part of May, but my guess is that they will be a little later than that this year. Meadow fritillaries are common some years and rare in others. If this is a good year for them they might show up now. Also, look for question mark butterflies.
Bronze coppers are typically not too common, but they might start showing up in mid-May. Even though they are small, if they are around you will probably notice them because they are spectacularly beautiful.
Already we will be losing windows to see some of the butterflies. If you don't see a Henry's elfin or an Olympia marble in the next couple of weeks you will probably have to wait until next year to see them.
So make a point of getting out in nature to enjoy the scenery. You should see some butterflies. But if you don't, enjoy the birds and the wildflowers. Listen to the frogs sing.
You owe it to yourself.
Until next time...
April 16-30, 2013
I saw three reports of butterflies seen in Iowa in March, and a few in the first part of April while we had some warmer weather. Then it turned cold again and none were reported.
The Wisconsin Butterflies website had no butterflies reported for March, but had a number reported for early April. Those butterflies were mostly mourning cloaks with a single cabbage white as well.
The last half of April will show a steady increase in the number of common butterflies that might be seen, and there are a small number of rare or seldom-seen species that add to the excitement of the hunt.
We should be seeing mourning cloaks, eastern commas, and question mark butterflies. Less common butterflies within the guild of those that over-winter as adults could include Milbert's and compton tortoiseshells--not common in central Iowa, but more so as you go east and north of the state.
The butterflies that may be common enough to be seen in the middle of this month include the spring azure, the cabbage white, black swallowtail, and eastern tiger swallowtail. By the last week in April and the first of May, we might see clouded sulfurs and pearl crescents (like the one shown just to the right).
There are a number of butterflies that migrate or immigrate into the state each year. Their numbers can fluctuate wildly, as they depend on summer winds associated with storms to bring them north. Red admirals, painted ladies, and American ladies might show up in fairly significant numbers. The American lady, shown below and to the left, has two large eyespots on the underside of its hind wings. The painted lady usually has four or five smaller eyespots.
Last year I saw dainty sulfurs in late April--I saw them first on a trip to The Ledges State Park, and later it seemed they were everywhere. I think, however, that 2012 will prove to have been a highly unusual year for that species and we won't see this species in Iowa until late in the summer this year.
There are some rare species to look for now, as well. I have seen and photographed most of Iowa's butterflies, and recently photographed some which are occasional or rare in Iowa in other states, but there are still some which I have yet to see.
The Olympia marble is a small white butterfly with beautiful green markings on its underside. It has one generation in Iowa. It can be found from late April through May. It is mostly found on the western tier of counties in Iowa, although I have reports of it being seen in The Ledges and even in Ames along the railroad tracks near North Dakota avenue. I have yet to see this one, and I hope to soon. Look for it low to the ground, in areas that have wild mustards growing. Rock cress is reported to be a host plant.
Henry's elfin is a small, brownish colored hairstreak which has one generation per year in Iowa. It has been found mostly in the southern part of the state, and its caterpillars feed on redbud. This butterfly can also be found from late April through May, mostly on its host plant. I have yet to find this one for myself--maybe I will get lucky this year.
The juniper hairstreak seems to have two generations per year in Iowa. Its host plant is eastern red cedar, and that can be found everywhere in Iowa. However, the butterfly does not seem to be all that common, or all that easy to locate. This butterfly seems to use the upper branches of tall cedars as a roosting point, and others have reported success by beating those branches with a net or a stick to get the butterflies to fly. I have tried that myself with no luck. I have seen this butterfly and photographed it, but I also want to get better pictures--this is one of our most beautiful butterflies. I have searched long hours for it, and I have not figured out a way to locate it reliably. The only times I have had success with this butterfly have been with the early brood--late April or early May.
Perhaps one of Iowa's most enigmatic butterflies is the white M hairstreak. This butterfly looks similar to the gray hairstreak below, although there is a distinctive white dash near the leading edge of its forewings. The dorsal surface of the wings of this butterfly are a brilliant blue, unlike the subtle shades of the gray hairstreak. The white M hairstreak may have three generations in Iowa, although it is only rarely seen. Perhaps Iowa is the extreme northern edge of the range of this butterfly, and it really is rare here. There has been some speculation that the white M hairstreak is a butterfly of the canopies, particularly of oak forests or savannahs, and is possibly more common than its sightings would indicate. There have been a handful of sightings in Iowa, and seeing this butterfly is a pretty big deal.
So get out and enjoy nature. Watch for the common butterflies and search closely for the rare ones. Enjoy.
|April 1-15, 2013|
So much of March was almost warm enough for flowers to start bursting out, and almost warm enough for butterflies. But the rest of it was cold and snowy. I may have been overly optimistic, thinking we might see butterflies in March. We will see if there are any last minute entries, but as of now I have not heard of any sightings of butterflies in Iowa yet.
The first of April usually has similar episodes--warm sunny days mixed in with the cool and rainy. Hopefully, the winter weather is behind us and the flowers and butterflies will soon be seen. I have seen crocus blooming, and that's a good sign.
We will see the butterflies which over-winter as adults when the weather is warm enough to encourage them out--mourning cloaks, eastern commas, and question marks. Other butterflies within this group are rarer, and less likely to be seen in central Iowa. They include the gray comma and Milbert's and Compton tortoiseshells.
Another group which should start making an appearance now are the butterflies that spend the winter as pupae. The first of this group that you are likely to see is the alien import cabbage white, shown here to the right. It is still about a month too early to see the equally alien dame's rocket that this butterfly is drinking nectar from, but the cabbage whites will be seen in sunny areas.
Spring azures will be seen flying several feet up in the trees of wooded areas. Black swallowtails and eastern tiger swallowtails may also be seen in this time frame.
Migratory butterflies may show up, carried by warm southern winds associated with thunderstorms. This group includes the red admiral, painted lady, and American lady. Red admirals are showy, conspicuous butterflies but they are also capable of disappearing on the forest floor, especially when they close up their wings like the red admiral shown below and to the left.
Some of the spreadwing skippers may show up in early April. The sleepy duskywing seems to have one generation in Iowa, and it can be found in oak forests in the early spring. Juvenal's duskywing is similar, and might be found in the same habitats.
This year seems to be warming up a week or two later than normal, and the difference is especially noticeable because last year was so far ahead of normal. It does have a tendency to balance out, however--hopefully this year will not be as dry or as hot as last year.
Warm weather should bring with it good numbers of butterflies, and a walk in a wooded area with good spring ephemerals will also have a nice population of butterflies.
I was fortunate enough to attend a conference at the Minnesota Zoo on the conservation of rare tallgrass prairie butterflies earlier this year. The Poweshiek skipper was featured prominently at this conference, as were other rare prairie butterflies. There were many people in attendance who have pretty good experience in conservation efforts for rare butterflies, and I was encouraged to see the effort and talent expended in the cause.
I think we need to look into conserving the butterflies that we consider common as well. We humans greatly modify our environment. We have been modifying the environment in small, incremental ways over a long period of time, and now those changes are seen as the normal state of things.
When we grow monocultures of crops, there is very little habitat left for butterflies, so that land produces few or none. When we grow monocultures of closely cropped grass, there is little to no butterfly habitat there as well. We are slowly getting wiser with our roadside ditches--planting prairie plants as part of an integrated roadside management program, rather than grasses or alien plants like birds foot trefoil.
So the challenge is this--rather than only conserving butterflies by setting aside and managing pristine habitats (which are increasingly rare), can we manage the existing modified landscape in such a way as to increase the quantity and diversity of butterflies?
One type of highly modified "habitat" that seems ripe for this approach is the storm water detention and retention structures that are increasingly mandated by regulations and green building management practices. Some of these structures seem to be obviously good butterfly habitat, (and I have surveys on some that show it) and others seem pretty poor in that regard. Perhaps with some attention to detail the poor habitats can become good. My impression is that new construction results in a lot of these structures and that typically the people who own them do have not given a lot of thought as to how to manage them.
We also see the brave individuals who buck the status quo and plant prairie or woodland plants in areas that others would only have mowed grass. They can have yards that are full of butterflies. Perhaps in a few years the idea will catch on with more people will do it.
If we could compare the numbers of butterflies we have now to what would have been present in the past, what would we find? I feel fairly comfortable with saying we may only have a tenth of what we would have had in the past, but the number could easily be an order of magnitude two less.
Conservation is a long term task. Enjoying butterflies is a short-term pleasure. When the sun comes out and heats the woodlands (and it will soon), get out there and enjoy them. Look at the spring ephemeral wildflowers--hepatica and snow trillium should bloom with the next sunny day, and the host of others which follow. Smell the smells of the forest. It will do your heart good.
|March 1-31, 2013|
| The butterfly season in Iowa usually starts
in March. Since the first butterflies that are seen each year
spend the winter as adults, it is possible for butterflies appear
outside on an especially warm February day, or even in January, but I
have never seen it (yet).
The weather does have to warm up a little bit. But once it does, you owe it to yourself to take a walk in the woods. Hopefully the frost will be gone, leaving the ground soft but not soggy. Mosses will be bright green. Some trees will have started to leaf out, and the first of the spring flowers will be blooming.
Every year it seems the first flowers to bloom are the same species. In the woodlands they are hepatica, snow trilliums, and pussytoes. In the prairie they are pasque flowers. In my yard I watch for crocus. Same spot, same purple crocus. But it is always exciting to see the first one.
The situation is the same with butterflies. The first butterfly you see each year is likely to be one of the same seen first every year. In Iowa, that is usually either a mourning cloak or an eastern comma. Maybe you can add the compton and Milbert's tortoiseshells to that list, but in my experience the tortoiseshells are not common in the areas I can get to.
The questionmark butterfly should, in theory, be part of that list--it also spends the winter in the adult stage, wedged into some crack in the bark of a tree or under the leaf litter. However, the question mark always seems to come out later than the others.
The sighting of the first butterfly is associated with the weather at this time of year as well. Recent first sightings have occurred as early as the first week of March, and as late as the last week.
Watch the sides of tree trunks for a little bit of moisture--sometimes sap leaking from a wound in a tree attracts the butterflies.
You might see little holes in the bark, usually several holes in a row that almost look like a human must have put them there with an electric drill. These are not the work of humans, however--they are the work of a small woodpecker called a sapsucker. Sapsuckers make the holes, and then come back to collect the insects that are attracted to the sap. How many times the first butterfly of the year has ended up as a sapsucker meal is not known.
The good butterfly days can be few and far between in March. I have to admit that some days when I am busy at work and the sun is out my mind is not really on the work. In my mind's eye I am walking through the woodland and I am feeling the sun on my face. I am watching high up in the tree trunks for the little flash of orange that shows the eastern comma.
If spring arrives early enough we might see other butterflies in March. The butterflies that overwinter in the pupal stage, especially cabbage whites, black swallowtails, and spring azures could make an appearance. More likely, they will not show up until April. Last year we had a very early spring and had red admirals in March. Other migratory butterflies, like painted and American ladies could also be possible, but I think they would be unlikely so early in a normal year.
There is something magical about the change of seasons. I know here in Iowa we complain about the winter a lot (and we generally have a good reason). But going out during the first warm weather week of the year is a magical experience, especialy if you can make it to a good woodland. The air gets a fresher smell to it, the colors start to brighten, and the birds sing a different song. Maybe the chorus frogs will be singing.
So bring on the spring and the butterfly season. I can hardly wait.