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Butterfly Forecasts for Central Iowa  
  April 2018  
  Cabbage whiteI was watching the weather forecast the other day and the meteorologist said that he was very tempted to give the forecast that he wanted, rather than what it will actually be.  So am I.  But his inaccurate predictions probably have more severe consequences than mine.  If you get rained on when you are expecting sun you might get angry.   Hopefully if you see a different butterfly than I predict you will see it won't have the same negative consequences as a bad weather forecast.
This year has been pretty slow for butterflies because of the cool weather.  I have heard of no reports of butterfly sightings in Iowa for March this year--we have only had a couple of days that were warm enough for them to be flying.  There have been several sightings in Wisconsin, per the Wisconsin Butterflies site.  The weather forecast for the first week or so of April seems to be pretty unfavorable for butterflies but spring will get here eventually.  When it does, we should see the butterflies that normally show up in March.  Butterflies that spend the winter as adults and emerge on warm spring days include mourning cloaks and eastern commas.  Gray commas, and Compton's tortoiseshells are not common around here but could also show up early in the spring.  Once the days start to heat up other butterflies will not be far behind.  
Cabbage whites often show up in early April.  It will be at mid-April at the earliest this year.  This species is common state wide.  A couple of other white butterflies might be seen--the checkered white has two flights, including one in April.  Olympia marble has only one flight, usually in early April to late May.  Both come from fairly specific habitats and feed on wild mustards.  Checkered white is often seen in its second flight, which occurs later in the summer, but not so often in April.  Olympia marble is historically reported from the Loess Hills area in the western counties of Iowa, a few counties in northeast Iowa, and Story and Boone counties.  It is notoriously difficult to find, which may be because it only flies for a short time in restricted habitats.  There have been some suggestions, however, that like several other butterflies it is no longer found in Iowa.  It is certainly worth looking for, though.  The most recent sighting on Jim Durbin's Insects of Iowa website was from 2006.Henry's elfin
Another butterfly that has a short flight time is Henry's elfin.  It can only be found in late April through early May.  Henry's elfin has uses several caterpillar host plants across its range, but in Iowa it specializes in redbud. It is found in the southern part of the state. This is a very small butterfly that looks pretty dark when it flies.  You have to look close and be in the right place to find it.  I have seen them in Cordova Park and Elk Rock State park, both of which are in Marion County.
Spring azures should start showing up about the end of the month.  If the weather is warm enough eastern tailed-blues will be around in April.  Other early butterflies include clouded sulfurs, eastern tiger swallowtails, black swallowtails, and American ladies.  Red admirals can show up early as well.

But the weather forecast has a great impact on butterfly numbers.  As I am writing this, there seems to be no good butterfly weather in it.  The warm weather will come.  But it seems to take so long...

Harlan Ratcliff 
 
  Little wood satyr  
  March 2018  
  Red admiralDon't you just hate winter?  Earlier last week I tried to get in my car but the doors wouldn't open because of the ice that was caked on it.  I had to tap around the edges of the door before I could get it open to get my ice scraper out.  Then I had to do the same with another door.  I started the car, but had to let it heat up for about twenty minutes before I could even get to the ice to scrape it.
We have had mostly dry weather earlier in the winter, and now we are getting that stuff the forecasters call a "wintery mix." But the days are getting longer, a few minutes per day.  And the weather will get warmer as well.
The butterflies are coming!
In most years the first butterflies of the year are spotted in March.  Sometimes it is not until the end of the month, but just as often they can show up during the first week.  2017 and 2016 were exceptional years, though, with early butterfly sightings in February.
Mourning cloaks and eastern commas spend their winters in Iowa in the adult stage, and are the most likely to be seen early on.  Gray commas and compton tortoiseshells have similar life cycles and might be possible as well, but they are not very common here so are less likely to be seen than the other two.
If you walk in the woodlands on a sunny March day, watch for sunny branches up high where you might see the eastern commas basking.  Look for moisture on the bark of trees.  That can be an indication of sap leaking from a crack in the bark or perhaps where a branch meets the main trunk.  It can also be caused by small holes drilled into the bark by sapsuckers (a type of woodpecker).  Early butterflies use that sap as a source of food, as flowers are not yet blooming.
Red admirals are generally considered to be migratory in Iowa.  They have been observed flying south in the winter and a different generation re-populates the state in the spring.  Large numbers can show up in the spring, often late April, but if the weather cooperates they might show up as early as March.  In additon to the migration, however, red admirals seem to have a little bit of plasticity in their life cycle.  In warm winters some individuals may be able to live through the winter as either adults or some other stage.  Last year, some of the first butterflies seen in Iowa were red admirals.eastern comma

Cabbage white butterflies spend the winters in the pupal stage, and are therefore very early butterflies as well.  Typically they start flying in early April, but they might show up in March if the weather cooperates.
The numbers will be small, and the total number of species that could be seen will also be small.  Still, one or two butterflies are better than none, and are a sign of things to come.
So get out in the wild areas of Iowa when you can.  Enjoy the sights, sounds, and smells.  Watch for butterflies.
Warmer weather is coming.  Butterflies will be here before you know.


Harlan Ratcliff


 
  Little wood satyr