|The Poweshiek Skipper Project|
|Butterfly Forecasts for Central Iowa|
|May 1-May 15, 2015|
days are getting longer and warmer, and butterflies are showing up more
reliably and in greater numbers than before. It might still be
possible to see some of the early single-generation butterflies like
Henry's elfin and Olympia marble. They can be quite difficult to
find, but look for them anyway because they are worth the trouble.
Two small blue butterflies will appear during this time period--summer azures and eastern tailed blues. Summer azures fly at tree-top level, or at least often end up there, and eastern tailed-blues typically stay away from the trees.
There is a complex of several Celastrina (azure) species (or subspecies, depending on the taxonomist), and two have been identified for Iowa, although others are possible. I discussed this in this post last year, so I won't go over it again.
Summer azures and eastern tailed-blues can both be present in the first half of May, although both will show up in much higher numbers later in the year. You may also still find eastern and gray commas, mourning cloaks, and Compton and Milbert's tortoiseshells are possible, but mostly in the north-east part of the state.
Last year I found goatweed leafwing and common roadside skipper on the fourth of May, but both were in the western part of Iowa, at West Oak Forest and Folsom Point Preserve, in Mills County. Neither of those butterflies are likely to be found in central Iowa.
Clouded sulfurs and orange sulfurs should be present and could become fairly common. In the field I am never completely confident of my ability to differentiate those two species, but the clouded sulfur is generally smaller and has a light yellow upper surface. The orange sulfur is larger and has an upper surface that is more of an orangish-yellow, but still more yellow than orange. There are some butterflies that are clearly one or the other, but there are many that are sort of in between. Generally speaking, the butterflies I see earliest in the spring and the latest in the fall usually look more like clouded sulfurs than orange. In the summer ratios can vary, often with one species dominating.
Common butterflies will also include cabbage whites, red admirals, American ladies, and painted ladies, any of which could be present in fairly high numbers.
Bronze coppers can often be seen around wetlands, but usually in low numbers. Although small, they are brightly colored and leave a pretty good impression. American coppers are rarer, although they can be present in high numbers where they are found. They are very small and can be overlooked quite easily, however.
Black swallowtails and eastern tiger swallowtails will make an appearance, and while not common they are large and showy and cannot easily be missed.
Skippers were generally uncommon last year but may be more common this year. The large silver-spotted skipper is always fun to see, as it hops around, landing underneath flowers and popping its proboscis over the top to get its nectar. Peck's skipper and hobomok skipper can often be found on some of the mid spring garden flowers.
The earliest of the monarchs can be seen in early to mid May in Iowa.
Of course, this time is full of other magical creatures as well. Flowers will be full of tiny insects--bees, wasps, and especially flies, all chasing the gift of nectar. Most can be difficult to identify, although some are so distinctive as to be easily identified.
Frogs can be heard calling often now. The gray tree frog will have replaced the chorus frog by now, and American toads, bullfrogs, and cricket frogs may be calling.
I had a fairly good education while I was growing up, and majored in biology at Iowa State. I got outside fairly often--maybe more than most, but less than others. But perhaps I did not pay enough attention, because I was unaware until after I had graduated college that there were terrestrial snails in Iowa. I knew there were slugs, which are snails that have an internal shell, but for some reason I had not made the connection with snails.
The featured creature for this forecast is a snail.
Turns out there are quite a few species of snails in Iowa. I have a list, although there is still a lot of work that could be done with the snails. There are a few large snails--those with shells between half an inch to slightly over an inch in diameter, but most are quite small. There really aren't any good field guides currently in publication, but there are a few older ones.
Most snails can be difficult to identify. The key characteristics involve determining whether the undersurface of the coil (termed the umbilicus) is open or closed, and looking at the opening or aperture to the shell--some have lips, and some have projections into the aperture. Then you measure the shell, count the coils, and note the color and texture of the shell.
There is a snail that is considerably easier than most to identify than most. Anguispira alternata is found in most rich woodlands. The umbilicus is widely open. The aperture has no lip or projections into it. The snail is fairly large, with a shell diameter of about 3/4 inch. The shell often has alternating red and clear stripes, and it appears sculptured. The slime this snail gives off is often reddish in color.
This snail often climbs high in trees, and the individual shown was several feet off the ground during a sudden rain storm.
So if you see a snail in the woodlands, often partway up the tree, and it looks like this you can be fairly sure of the I.D. This is a fairly distinctive species, and no other Iowa snail looks much like this one.
So get outside and watch for butterflies and all the other creatures that make the season fun.
|April 16-April 30, 2015|
the days continue to get longer and the warmer the butterflies are
coming out in higher numbers than earlier in the spring. Still,
the weather can determine whether any butterflies are seen at all.
Long rainy days or late frosts can mean that none will be seen.
Sunny warm days can result in lots of them.
The nymphalids that spend the winter in the adult phase--mourning cloaks, eastern commas, gray commas, Milbert's tortoiseshell and Compton tortoiseshell can still be seen in wooded areas. Migratory butterflies, mostly from the same group, can also be seen. Red admirals, American ladies, painted ladies, and buckeyes can be seen, sometimes in fairly large numbers. Then there are some of the resident butterflies that come out a little later. Cabbage whites are usually among the first of these, followed by clouded and orange sulfurs.
Eastern tiger swallowtails can be conspicuous and somewhat common in the spring. Black swallowtails are often found in pretty good numbers also. However, black swallowtails were almost absent from the landscape last year, at least here in central Iowa. I hope their numbers rebound this year.
The last half of April marks the emergence of what I call "frustration butterflies." These are butterflies that are either difficult to find, either because they are rare or because they only come out for a short time in specialized habitats. The fact that I have posted this forecast for a number of years has led some people to think I am an expert. I am not--I am an enthusiast. And often times I am a frustrated enthusiast. I can spend lots of time looking for butterflies that others seem to find easily. But maybe they are frustrated also.
The juniper hairstreak is one of my frustration butterflies. I have been lucky enough to see it on a handful of occasions, and to get photographs. But the amount of time I have spent searching for this little gem is way out of proportion to the number of times I have seen it. Eastern red cedar is a hostplant for this butterfly, and is also a tree which grows like a weed around here. Juniper hairstreaks are probably more common in the western-most counties of Iowa, and also some counties in the eastern part of the state. I have seen them in my yard on two occasions, but I have gone out specifically looking for them on dozens of occasions. This butterfly seems to have two generations in Iowa, one in late April and early May, and another in late June through early August. The few times I have seen it have been in the first generation, although I have looked for it extensively in the second generation as well.
Another frustration butterfly for me is the Olympia marble. I have yet to see this one. It is rare, and when it is found it is mostly found in one of the western counties of Iowa. I did hear of a report of someone who found them in an area of Ames in in The Ledges State Park, but some other people I talked to about those reports were somewhat surprised by them.
Olympia marble uses small native mustards like rock cress as host plants. They are reported to occur only in small numbers in Iowa when they are found at all. Mike Reese (Wisconsin Butterflies) describes trying to photograph them as the fly and nectar on pasque flowers, and notes that they are skittish and very difficult to photograph.
My final frustration butterfly (at least for this time period) is Henry's elfin. I have yet to find this butterfly either. It is a small hairstreak with a short flight period that coincides with a very busy time of the year for work and school activities, and short weather windows for locating butterflies. But it is known mostly from native redbud trees, and I have finally figured out how to reliably identify redbuds. I will find this butterfly if I keep looking for it--at least that is what I tell myself. I have all the information I need. I just need some good timing and luck.
A few other species of butterflies should be seen, and will be easier to find than the frustration butterflies. Spring azures are small blue butterflies that can be found flying high in woodlands in late April. Eastern tailed-blues might also be flying, but the peak of their first flight normally comes a little later. Eastern tailed-blues usually fly closer to the ground than spring azures. Watch for pearl crescents and possibly even silver-spotted skippers.
Late April is a great time to be outside enjoying nature. The woodland floors are alive with flowers--spring ephemerals as they are called. Hepatica, bloodroot, spring beauty, Dutchman's breeches, and May-apple can be found in abundance on forest floors all over Iowa. If you are lucky you might also find squirrel corn, wood-betony, large-flowered bellwort, showy orchis, Solomon's seal, false Solomon's seal, and wild ginger. These wildflowers will be visited by small solitary bees and beeflies. Some of them have pollinators or other visitors that are specialists--they can only be found on that particular flower.
If you do not know Iowa's woodland wildflowers, and especially if you don't get out and walk the forest floor in mid to late April in Iowa you are really missing out. Try to get away from everybody, but you might run into mushroom hunters this time of year. But if you are one of the mushroom hunters, take some time to enjoy the wildflowers and small critters.
If you get to a pond or lake, you will find that the dragonflies and damselflies are still pretty uncommon this time of year. You may see a few large dragonflies cruising the perimeter of the pond, or maybe just a single individual. It is likely to be the common green darner, Anax junius.
For this butterfly forecast, my featured (non-butterfly) creature is Anax junius.
Common green darners are migratory. The exact details of where and when they migrate are still being worked out. Other dragonflies are migratory as well, but the general phenomenon is not well known. There is a citizen-science project that is gathering information, and it is called the Migratory Dragonfly Partnership. This project monitors five species that are known to migrate.
Of course, if you want to know more about Iowa's dragonflies and damselflies, don't forget about the excellent Iowa resource, www.iowaodes.org. This lists all known Iowa species and includes their flight times, biology, and excellent photographs.
So get outside and look for butterflies. Watch for common green darners. Walk in the woods and enjoy the spring ephemerals. Listen for the sound of bees flying, and the calls of frogs looking for mates. Take in the sun and the cool breeze.
You will be glad you did.
|April 1-April 15, 2015|
gave us temperatures that were twenty or thirty degrees colder than
normal. When I published my first butterfly forecast for this year, I thought we
would be well into March before we would see any butterflies. But
then it warmed up to temperatures that were about the same range above
normal. Before long, the snow was mostly gone and a few reports of
butterfly sightings started trickling in.
The first butterfly sighting in Iowa that I am aware of was from Kevin Pape in a new Iowa DNR property called Spirit Knoll, recently renamed Heendah Hills. Kevin saw an eastern comma on March 9th. Then I got a report from Lloyd Crim of a cabbage white seen on March 10th. Benjamin Hoksch reported seeing an unidentified Polygonia species on the 11th. Chris Edwards reported a gray comma on March 16th, and Armund Bartz reported a mourning cloak on March 14th.
People were reporting butterflies on the Wisconsin Butterflies site starting on the 9th of March as well. The first ones seen were all eastern commas or mourning cloaks.
Generally speaking the first butterflies we see are the ones which hibernate as adults. These include the commonly seen mourning cloak and eastern comma, and also less common (around here, at least) gray comma, Milbert's tortoiseshell and compton tortoiseshell.
The cabbage white is one of a group of butterflies that spend the winter as a pupa, and it is generally one of the first to be seen in the spring. Others we are likely to see soon include the spring azure, the clouded sulfur, and the black swallowtail.
Most of the butterflies we have here in Iowa are native to the state. The cabbage white is not. It is originally from Europe, where it has the common name "small white." In The Butterflies of North America by James A. Scott, a study is mentioned where cabbage whites were marked and followed as the moved throughout the day. It was noted that the females flew a distance of about 700 meters every day, and usually ended up about 450 meters from where they started. Each day they would fly in a preferred direction, but that preferred direction could change, apparently at random, the following day. Adults lived only about five days. So the next time you get to observe cabbage whites, see if you can detect a preferred direction of flight. If they reach the edge of their habitat do they keep going, or do they fly back?
The migratory butterflies can start showing up in the first part of April, depending on the weather. Red admirals can be very common, and usually American ladies or painted ladies can show up as well.
Henry's elfin and Olympia marble are butterflies which only fly in spring in Iowa. They might show up in early April, but they are more likely to be present in the last half of the month or even in early May. I have been frustrated in my attempts to find these species and have been unsuccessful so far. For those of you in the same boat, my best advice is to check out the website www.insectsofiowa.org for those species. The database gives lists of locations and times, and if you are lucky enough to know one of the individuals who has documented one of the specimens maybe they can help you.
Early spring brings lots of changes to the landscape. If you are able to visit one of the woodlands around Iowa with a good understory of spring ephemerals, you might be able to find something new each time you visit. There are a lot of small solitary bees flying at this time of year. All of your senses can be involved in the experience, from the smell of the nightcrawlers after a spring rain, the softness of the moss growing on the earth of the forest floor, and the sounds of the birds and frogs singing, or the bees and flies buzzing around. The flowers let you appreciate your sense of sight. I am sure there are plenty of things to taste, as well, but let me recommend morel mushrooms (just starting their season) and maple syrup (at the end of its season).
I have written this butterfly forecast for several years now, and I thought I might spice it up a little bit from time to time with other creatures you might want to look for. Butterflies are only a small part of the biological diversity of Iowa, and there are other things that can be fun to watch for.
The first featured creature is called the "golden dung fly." This is a fairly distinctive and common fly here in Iowa. They are found all over the United States and are most common in the early spring and summer, then again in the fall.
Golden dung flies are slightly larger than a house fly, and have noticably thicker and longer legs. They are golden-yellow, and covered with golden yellow hairs. The adults seem to be attracted to areas with sugars--wounds of trees that are leaking sap and flowers. When peonies first start to bud you can often find them on the sugary buds, along with ants and other species of flies.
Although the adults seem to be attracted to sugars, they are not nectar feeders--they capture and eat other insects. They seem to be quite good at it, in fact.
Eggs are deposited on decaying vegetation and on animal dung. I am no expert on Latin names, but I can tell you that the "phaga" part of the name refers to eating. I will let you fill in the rest.
So get out there and look for butterflies. Listen for the calls of frogs. Watch for other creatures as well. And see if you can find a golden dung fly.
Enjoy the outdoors.
|March 1-March 31, 2015|
is March, so it must be butterfly season. In Iowa, butterfly
season almost always starts in March. It might be the first day of
March, or it might be the last day. There is about a 98% chance
that the first butterfly seen in the Iowa each year will be seen in
March. It is also likely that it will be either a mourning cloak
or an eastern comma.
How do I know that? I don't really. But I have done this forecast for six years now, and in each of those years the first butterfly showed up in March. The first butterfly reported in Iowa for those years was either a mourning cloak or an eastern comma. I recorded reports as late as March 30 and some as early as March 16. In a couple of years I reported that butterflies had been seen in March, but did not record the actual dates. In 2012 I reported that I had seen four species by April, but did not record which species or when they were seen.
Mike Reese does a better job on his Wisconsin Butterflies site. He has records from 2005 through 2014, and the ability for others to submit records. The first butterfly sightings on his website are all in March for that time period, and include Compton tortoiseshells and Milbert's tortoiseshells in addition to eastern commas and mourning cloaks. Those tortoiseshell species are not so common in central Iowa and so are less likely to be the first butterfly seen.
Butterflies are fun to watch. It can also be fun to keep records of what you see and to share those records with others. Those records can really help your success. A number of websites out there encourage this type of citizen science, or are created by citizen scientists. Each is slightly different and can be used for different things.
Jim Durban has created a database to track Iowa's insects. His first version is still online at insectsofiowa.com. He has a greatly modified and improved version at insectsofiowa.org. Both sites are useful on a number of levels, but the last version looks to be particularly useful for people who are trying to find the rarely seen butterflies of Iowa.
When you talk about butterflies someone always asks if there are fewer now than there used to be. The answer is usually that it seems like there were more back then, but how do you know for sure?
There is an answer to that question. The British Butterfly Monitoring Scheme was developed in the 1970s and has been used successfully to monitor butterfly populations in Great Britain. The primary survey technique, the "Pollard Walk," has been adapted and used by several butterfly survey efforts in the United States. A Pollard walk involves walking at a steady pace along a set route and identifying and counting all of the butterflies seen along that route within a given distance from the observer. Usually the observer conducts similar surveys along that same route several times during the season. The data can be reduced to numbers of a particular species seen per hour, or numbers seen for a given area. It can also give valuable information about what was not seen in a given time.
Nathan Brockman and Reiman Gardens have set up an Iowa Butterfly Survey Network effort for Iowa, and it has been making steady progress. Last year they fielded a new smartphone app for surveying butterflies. Now they are coordinating with others to input information into a national database for Pollard walk-type data, and it can be found on the Butterflies and Moths of North America website.
But enough about websites and databases. What we really want is to get outside and look for butterflies. Hopefully within a few weeks we can string a couple of warm days together, and the sap will start to flow in the trees. When that happens take a walk in a woodland. Where small branches have broken or cracked , or where sapsuckers have drilled holes you may see the sap running down the trunk of a tree. Check those areas especially--they are great places to find butterflies. Mourning cloaks, eastern commas, and the tortoiseshells can be found here. They also might be seen sunning themselves on a well-lit tree trunk, or flying through the understory.
Late in the month, if we are lucky enough to have some warm weather, we might see red admirals, cabbage whites, or spring azures. So much of the early butterfly season depends on the weather. But hit a good woodland in the early spring. You will be glad you did.