|The Poweshiek Skipper Project|
|Butterfly Forecasts for Central Iowa|
|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.