Photo of the Week – August 3, 2017

Quick note on this Saturday’s Field Day.  We will be there rain or shine, and have indoor presentations , if needed, if rain keeps us from seeing insects outdoors during part of the day.  Please come join us for this free event!

A painted lady nectars from lanceleaf blazing star in the Platte River Prairies this week.

All of a sudden, painted lady butterflies have exploded onto the scene here in central Nebraska.  They are fluttering around all the flowers in our yard and are abundant in our prairies as well.  Painted lady butterflies are migratory, but this latest flush isn’t due to a new set of arrivals from further south.  Instead, a new batch of adults has just emerged after spending the last several weeks as caterpillars in prairies and other locations – including soybean fields.

In soybean fields, the caterpillars are known as thistle caterpillars and feed on the leaves of the bean plants.  According to my father-in-law Orvin Bontrager, a long-time agronomist, they don’t usually do enough damage to impact yields, though the damage can look a little scary to farmers.  For the rest of us, there’s nothing scary about these welcome accents to wildflower patches everywhere.  Here are a few more photos from this week of painted ladies in my yard and nearby prairies.

…on black-eyed Susan in our yard

…on whorled milkweed in our yard

…on rosinweed in the Platte River Prairies

…on Flodman’s thistle (native wildflower) in the Platte River Prairies

 

(Fun fact – painted lady butterflies are found on every continent except Antarctica and Australia.  They also some make migratory flights that make monarchs look like amateurs.  Speaking of monarchs, they inhabit a larger slice of the earth than you might be aware of too…  Don’t get me started, I could spout insect trivia all day!)

Intercontinental Insect Migration (!)

Insect migration is a world we’re just starting to discover, and the more we find, the more fascinating that world is.  One of the most recent discoveries involves Painted Lady butterflies (Vanessa cardui), a species found on every continent except Australia and Antarctica.  Scientists in the United Kingdom knew that millions of painted ladies migrated north from North Africa each year.  Until recently, they assumed it was a one-way trip.  Now, innovative radar techniques show that the species migrates back to North Africa, taking advantage of high-altitude winds (up to 500 meters off the ground).  

A painted lady butterfly in Nebraska – feeding on Baldwin’s ironweed (Vernonia baldwinii).

In case you’re wondering why painted lady butterflies would bother making the trip, the results from radar readings showed that in one year about 11 million butterflies came from Africa to the United Kingdom, and 26 million went back – so the species apparently benefits from migrating.  (The butterflies that return are the offspring of the ones that come).  You can a further description of the study here from Science Magazine’s website, and link from there to the full scientific article.

Back in May, I posted about what is being learned about how moths and butterflies migrate in North America.  The story is similar, except that (at least at this point!) we think the majority of species migrate northward in the spring, but don’t return south.  Sounds like a great project for someone to look into!

Monarch butterflies in the Platte River Prairies – Nebraska.

I’m particularly fascinated by multi-generational migrations.  In North America, we’re familiar with the monarch butterfly migration, which takes place over four generations – each successive generation traveling the next leg of the journey.  The fact that each new generation of butterflies knows where to go and how to get there, without having been taught, is about as fantastic a natural phenomena as I can think of. 

Monarchs are not the only four generation insect migrant.  In fact, there’s a fantastic story about the globe skimmer dragonfly that migrates back and forth from India to Africa over four generations as well – using high-altitude wind currents like the painted lady butterfly.  You can read more about that dragonfly migration here.

Continuing advances in technology are allowing us to learn more and more about the lives of insects and other small creatures.  We’re starting by looking at the migrations of large showy insects such as butterflies, moths, and dragonflies, but I wonder how many smaller, less charismatic species are making long-distance trips that we’ve just never noticed.  I’m looking forward to reading many more fascinating stories as the data keeps coming in.

Don’t you just love science?