|The Poweshiek Skipper Project|
|Butterfly Forecasts for Central Iowa|
numbers and diversity start picking up in June. By the end of June
the butterfly populations will be between ten and a hundred times what
they averaged in May.
Question mark butterflies can be seen often in June, basking with the wings spread and exposing their bright orange and black uppersides. Question marks are larger than the similar eastern comma, and usually have a longer tail (although that characteristic is highly variable). They have two distinct morphs, a uniformly brown winter morph and the more mottled summer morph that is shown here. They may overwinter as adults, but they have also been documented to migrate in some places.
Other brushfoot butterflies that will be seen and sometimes will be quite common include eastern and gray commas, American ladies, and painted ladies. Red-spotted admirals (also known as red-spotted purples) will be seen near wooded areas as will viceroys as well.
We might see a few monarchs at the beginning of the month, followed by a dry spell. By the last week of the month we should be seeing them again in higher quantities.
By the middle of the month numbers should really be picking up, and we might see the first great spangled fritillaries, hackberry emperors, northern pearly-eyes, and little wood satyrs. Common wood nymphs will become quite common--in some dry prairies they will be the most common butterfly seen in the middle of the day.
Of course, pearl crescents will be quite common. Silvery checkerspots can be common, especially in wooded areas. Prairie areas may have gorgone checkerspots mixed in with the other two.
Black swallowtails, eastern tiger swallowtails, and giant swallowtails should be possible throughout the month. They might not be common, but are large and easily seen when present.
The orange sulfur will likely be the most common butterfly throughout Iowa for the entire month, and for the rest of the summer. Clouded sulfurs and cabbage whites will be common as well. The first little yellows may show up by the end of the month, as well as dainty sulfurs in specific habitats.
Among the gossamer-winged butterflies two blues will be very common. First, the summer azure will have a population peak starting in the first or second week of June. They will be present until late in the summer. Eastern tailed-blues have already been seen, but they will become quite common by the latter part of the month. Bronze coppers and gray coppers will be found toward the end of the month, but usually only in certain habitats--usually wetland areas or good prairies.
By the end of the month several hairstreaks will make appearances. Coral, banded, and Edward's hairstreaks can often be found on milkweed flowers in areas that have trees of their host species--cherrys, oaks, hickories, wild plum, and others. They can also sometimes be seen chasing each other near the host tree.
Acadian hairstreak uses willow as a host plant, and is rare but can sometime be seen in wetland areas. Juniper hairstreak has a second generation which starts at the end of June and the first part of July. While the host plant, eastern red cedar, is found all over Iowa, sightings are more likely to occur along the western or eastern borders of Iowa for some reason.
Harvesters can be found all summer, having multiple overlapping broods. However, they are always rare.
Many species of skipper show up during June. We should see the large, fat, silver-spotted skipper along with a number of smaller spreadwings. Common checkered skipper and common sooty-wing can usually be seen. Horace's dusky wing and Juvenal's duskywing may both be present--I have to admit that I find them frustratingly difficult to tell apart. Peck's skipper is small and quite distinctive and usually common enough to be readily seen. Least skipper is small and light brown with a bright white belly. Once you have recognized it, this skipper is easily distinguished from the other skippers found in Iowa.
I plan on having a butterfly field trip on Saturday, July 2. We will go to Rolling Thunder and Medora Prairies. It will start at about 9:30 am at Rolling Thunder, and we will proceed from there at about 10:30 to Medora Prairie. I will put more details out on the Iowa Insect and the Iowa Native Plants listserves. If you are not on either list, you can email me (harlan(dot)ratcliff(at)gmail(dot)com) and I will send you the specifics.
It is likely to be hot, so bring water. Prairies also have plants that poke or scratch, and poison ivy, so the smart people will wear long pants or long-sleeved shirts. (I will probably wear shorts--I am kind of used to this stuff). There will be biting insects and ticks.
If we are lucky, we should be able to see regal fritillaries. There are also good populations of gray coppers, common wood nymphs, great spangled fritillaries, and coral hairstreaks.
Several rare skippers have been found in these two prairies, but in my experience they can be quite rare so if we see any of them we should consider ourselves lucky.
The visit will be non-consumptive: Emphasis will be on observing butterflies and not on catching them.
So mark the date. I hope to see you then.
brings summer weather.
Hopefully we will see some of that when the rains stop in a few days.
We will see the flowers of May along with its butterflies.
The diversity of the butterflies on the wing increases throughout the month, although sometimes the numbers can be a little disappointing. If you were to graph the populations over time for Iowa's butterfly species, you would find most of them have what statisticians call a "normal" distribution. Those with one generation have one peak. Some species have three peaks. The month of May usually falls within the distribution curves for many species, but the peaks are usually earlier or later.
Cabbage whites are fairly common and can be among the first butterflies to emerge in late March or early April. They don't all emerge at the same time, and they reach a population peak in mid to late April, depending on the weather. Adults live for about three weeks. You might see the adults remaining from the first generation in early May, and you might see some from the second generation in late May, but the peak populations fall outside of the month.
Henry's elfin and Olympia marbles are both rarely seen in Iowa, with the Olympia marbles possibly extirpated or nearly so. Both have population peaks in April but they can also be found in May. Look for Henry's elfin near redbud trees in the southern part of the state.
Clouded sulfurs have been fairly common and will continue to be. In my experience, orange sulfurs and clouded sulfurs are often similar enough in appearance that they are difficult to distinguish, but the ones that are clearly a little larger and have more orange (orange sulfurs) are usually more common when the weather gets warm, while the smaller, more yellowish clouded sulfurs are most common in early spring and late autumn.
Black swallowtails and eastern tiger swallowtails should be seen throughout May, and giant swallowtails will come out in the later half of the month. Those three can be found all over the state. Although they are sometimes uncommon they are large and easily seen. Zebra swallowtails should be out as well, but they are only reliably found in the extreme southwest corner of the state. While spicebush and pipevine swallowtails can occasionally be found in Iowa, they are rare and do not have resident populations in the state.
Red admirals are quite common right now and should continue to be for a while. You may see American ladies and painted ladies as well. Eastern commas may still be seen, but the slightly larger question mark butterfly is more likely to be seen in May. Toward the end of the month we should start seeing red-spotted admirals (formerly called red-spotted purples) and viceroys. First sightings of monarchs will probably happen in May, but they will still be uncommon.
Small numbers of eastern tailed-blues may be fund in the first part of the month, followed by larger numbers of summer azures sometime later.
Silver-spotted skippers, hobomok skipper, Peck's skipper, and common sooty-wing skipper are all possible in the last half of the month. Their numbers vary from year to year--sometime they can be quite common, and sometime they can be difficult to find. Watch flowers for their nectar-seeking visits.
Get outside and enjoy the butterflies.
seasons seem advanced by a week or two this year due to warm weather.
For the first time since I have been tracking butterflies we had some
butterflies observed in February in Iowa. Sibylla Brown saw a
comma on February 20 in Decatur County, Bill Witt saw a mourning cloak
in Cedar Falls on February 27, and Mark Brown saw a cabbage white in
Dubuque on February 28. Jim Durbin's database at
insectsofiowa.org has a single record
for a mourning cloak on February 24, 1998, but the others are probably
new early records.
Chasing butterflies in April is fun. It is fun because it is finally time to get relief from the long winter. The air always seems cleaner and fresher in April. Many of the butterflies you find will be first of the year for those species. And there are a couple that can only be found in April or perhaps early May in Iowa.
The large brushfoot butterflies that spend the winters as adults may still be around--eastern and gray commas and mourning cloaks are the most common in this area. Compton and Milbert's tortoiseshells fall into that group as well but are not nearly so common.
Cabbage whites are always early emergering butterflies, as are black swallowtails and azures. There seems to be a lot of discussion about whether the azures we see in April are spring azures, Celastrina ladon, or a spring-emerging brood of summer azure, C. neglecta. I think it is safe to say that the issue is pretty complicated, and the experts do not all agree. One discussion of the forms found along the east coast can be found here, and argues that most individuals found early are summer azures. Spring azures are present but rare. Jeffrey Glassberg suggests that all found in the spring are one species, and those later in the year are a different species. In addition, there are a number of species described based on hostplant preferences and other things. Bugguide also has some discussion of the various forms.
Olympia marbles have been found in Iowa in the past. There is some thought that they have been extirpated from most of the sites they have been found in the past, but there have been a couple of recent sightings of individuals. This butterfly is known to be difficult to locate, and may be overlooked. Late April through early May is the time to look for them here.
Henry's elfin is another butterfly that can only be located in the same small April/May time window. They can be found on and around redbuds. One of the best places to look seems to be the parks on and around Lake Red Rock. There have been sightings in Cordova Park on the north side of the reservoir and from Elk Rock State Park on the south side. Look in and around redbud trees and on nearby flowers. I have really only seen them once, and I did that by sitting on a chair near a redbud tree, and looking up into the tree. After about twenty minutes I saw an individual, and I saw another one later.
I used the same technique a few days later at the Ledges State Park, and watched redbud trees for an entire morning. I didn't see any then. Either they are not found there, or maybe they weren't out that day, or my method doesn't work well and I just got lucky once.
Hairstreaks that have trees as host plants often perch on the tree, then fly out in short little flights, chasing individuals of the same species. Juniper hairstreaks, which will have a flight in late April and early May have a similar behavior. I have been lucky enough to see juniper hairstreaks on my own property in central Iowa, but they are probably more reliably located in western Iowa in the Loess hills.
The Vanessa species--red admiral, painted lady, and American lady, may show up in some numbers in mid to late April. Royce Bitzer already documented a couple of painted ladies in Ames in early March. Red admirals are often quite common and showy early butterflies, and are often present in high numbers early.
By the end of April we should see eastern tiger swallowtails, eastern tailed-blues, and clouded or orange sulfurs. Pearl crescents should be chasing each other around the taller flowers.
I mentioned in the last post that I would try to organize some butterfly excursions this year. I want to try one on Saturday, April 23, and another one in late June or early July. I am not sure right now what the interest level will be, or how many people if any will want to be involved. I will experiment a little with some different formats to see if there is interest and what people want to do. I plan to do the second on in sort of a field trip format, trying to get a group that sort of stays together. I am planning it for central Iowa, with regal fritillaries as the primary target, and possibly some rare skippers as a secondary target.
The first trip will be a little bit more like a scavenger hunt, and will be in southwest Iowa. I would encourage people to meet up initially, then disperse over a wider area and look for some rare butterflies. Fulsom Point Preserve and West Oak Forest will be the initial locations (we will likely run across mushroom hunters). Other locations may be visited, depending on individual preference and tolerance for physical activity and/or driving. I would expect to leave the Des Moines area by 8:00 am and return by late afternoon. Contact me by email if you are interested in participating: (harlan(dot)ratcliff(at)gmail(dot)com). Include a phone number where you can be reached if there is a need to cancel or postpone.
I will send details out by email and also post them to the Iowa Insects listserve.
|March 1-31, 2016|
you feel the days getting longer? Warmer weather is just around
the corner, and with it come the butterflies. We might see some by
the end of the week.
In most years, the first butterflies of the season show up in March. There are really only a handful of species that are normally seen this early. Mourning cloak, eastern comma, gray comma, Milbert's tortoiseshell and Compton tortoiseshell all over-winter as adults and are the first butterflies seen in Iowa. Of those, mourning cloak and eastern comma are by far the most common in central Iowa, the others being more likely to be seen in wooded areas in the north eastern part of the state.
Watch for wet spots on tree trunks--telltale evidence of leaking sap. These butterflies in particular are attracted to sap and can often be found in abundance anywhere it is found.
In some years only a few individuals will be seen late in the month. If the weather is consistently warm for long enough we might see cabbage whites, clouded sulfurs, or red admirals by the end of the month. Cold years we have to wait until April to see them.
The low numbers and lack of diversity we see in this month are compensated by the joy that we feel just to see a first of the year butterfly, and we know the season will gradually get better. It is always good to get out into a woodland early in the year to look for the earliest flowers and hope to see a butterfly. Some woodlands have spectular shows of spring ephemeral flowers, but before they show up you might notice the green lush displays of mosses and liverworts, and the exotic colors of lichens. The smells of the slowly warming woodlands are terrific also, and alone are worth the trip.
This is my ninth year of posting a butterfly forecast, and I have enjoyed doing it. I am going to change things up a little bit this year, however. I plan on posting once per month this year, rather than twice as I have done in the past. I also plan on having two or three butterfly excursions this year within Iowa. These will be very informal, and open to the public. It will include visits to habitats within a particular geographic area of the state, and I will come up with some plans for looking for particular species. Depending on the number of people who show an interest and where they are from we can car pool, and we might go as a group or disperse into smaller numbers.
Watch for more details in the April forecast.
If you are looking for a nice social activity related to insects, check out the Day of Insects at Reiman Gardens. It is coming up in early April, so sign up soon.
There are a few web sites that can give clues about what butterflies are flying. The North American Butterfly Association recent sightings page lists butterflies seen all over the country. Right now they are showing sightings mostly from the southern states, but as the butterflies show up in the more northern states they will be reported there as well. Unfortunately, Iowa is not represented as much as I would like to see. Wisconsin butterflies lists recent sightings, although we usually see them here before they do up there. (As I was writing this, I checked the site and see that there have been two eastern comma sightings already this year in Wisconsin). Butterflies and Moths of North America has a recently verified sighting page--some are recently recorded, and some are just recently seen. You can even find hints about recent sightings on bugguide.
Of course, if you are looking for a specific butterfly you can get a pretty good idea when it shows up in Iowa by checking out the Insects of Iowa web site for that species.
So get out and look for butterflies. They have already beaten us in Wisconsin.