Category Archives: Prairie Natural History

Photo of the Week – May 5, 2017

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During the last week, I’ve been lucky enough to find and photograph two different wolf spiders, so I figured I should probably dedicate a short blog post to them.  The first wolf spider I found was a cute little bugger out in the prairie the other day.  I was out looking for monarch eggs and caterpillars and saw the spider scurry between clumps of vegetation.  Since I had my camera in hand, I stopped and had a visit.  The second spider was in our basement and was considerably bigger (2 inches in diameter with legs).  I took it outside where it could be happier, and photographed it before letting it roam freely in our garden.

This big beautiful wolf spider was in our basement before I put it back outside.

There are a lot of big fuzzy spiders that resemble wolf spiders, but true wolf spiders have a characteristic eye pattern that sets them apart.  If you look at the above photo, you can see that there are two large eyes above a straight row of four smaller eyes.  If you look even closer, you might be able to see two additional eyes behind the big ones that point up and to the sides.  You can see those last two eyes more clearly in the photo below.  The layout of those eight eyes is unique to wolf spiders, so if you ever wonder if a big fuzzy spider is a wolf spider, just look it in the eyes and you’ll know.

In this photo, it’s easier to see the wolf spider’s non-forward facing eyes.

There are more than 2,000 species of wolf spiders across the world, and they are a fascinating group of creatures.  Although they are free-roaming spiders (they don’t create a web and hang out on it), they still use ambush as their primary means of hunting.  They’ll usually sit quietly and wait for prospective prey to come within striking range. Wolf spiders hunt mostly at night, and their eyes are well-adapted for seeing in low light.  However, wolf spiders are also very adept at sensing and using vibrations to identify their prey.  Their hairy legs aren’t just for looks; they also act as part of a complex system of vibration sensors.  Wolf spiders can distinguish between patterns of wing beats or footsteps to help them determine what kind of creature is coming near.

This small wolf spider was out in the prairie while I was looking for monarch caterpillars.  Its body and legs were about a half inch in diameter.  Note the distinctive eye pattern that characterizes it as a wolf spider and the different kinds of hairs on the legs.

My daughter made me proud the other day by telling me she was able to impress her college friends with some of my favorite spider trivia: the reason spider legs always curl up when they die.  Spiders have flexor muscles on their legs (muscles that pull the legs toward their bodies) but not extensor muscles to push them back out again.  Instead, they use hydraulic pressure to extend their legs.  A fluid called hemolymph is pushed into the legs, counteracting the flexor muscle pressure enough to extend the legs.  It sounds like a cumbersome system, but if you’ve ever seen spiders run and jump, it’s clear that it works very well.  When a spider dies, it no longer has hydraulic pressure in its legs to counteract the flexor muscles so the legs naturally curl up toward the body.

Don’t you just love spiders?  Of course you do.

Here’s the big female one more time, just before she turned away to go explore our garden.

Frosty Monarchs

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Adding insult to injury, the overly-ambitious monarchs in Nebraska this spring had to deal with cold wet weather all last weekend.  Temperatures got down to about 30 degrees F, and maybe lower in some places, and much of the prairie was covered in frost at least one morning.  During the days, it was rainy, windy, and cold.

We’d brought several monarch eggs from our garden into the house so we and the kids could watch them develop, and the caterpillars from those eggs seem to be doing very well.  When I went back to the garden, though, I didn’t find either eggs or caterpillars on the remaining plants.  I don’t know what happened, but I wonder if the caterpillars hatched out and then didn’t make it through the weather.  Maybe they’re just hiding really well?

Yesterday, I was out at our Platte River Prairies, and Katharine (Hubbard Fellow) and I spent a couple hours walking around and looking for caterpillars on milkweed with no luck.  In addition, the frost killed the tips of most of the warm-season grasses that were just emerging from the ground, and also wilted a lot of the common milkweed plants.  Interestingly, the whorled milkweed plants I’d seen caterpillars on during previous week seemed to have handled the cold just fine, but we couldn’t find any caterpillars on them.  We did find a few eggs on common milkweed plants, but it’ll be interesting to see how quickly those plants recover from the frost, and whether or not they are able to provide sufficient food for any caterpillars that hatch from those eggs.

This common milkweed plant looked a little wilted from the frost, but looked a lot better than the warm-season grasses surrounding it.

The common milkweed plant on the left was more typical of most of the plants we saw on our walk yesterday. Note the whorled milkweed on the right side of the image (skinny green leaves) – it looks perfectly fine.

This was one of several monarch eggs we found on common milkweed plants yesterday.  We found eggs on whorled milkweed as well.

There was good news from the day, though, which is that I saw two adult monarchs, one of which was nectaring on dandelions.  Maybe we’ll still see more eggs laid by this early migrant population.  Temperatures for the next couple weeks look pretty good, so those eggs might have both bigger milkweeds than their earlier counterparts and better weather as well.

This was one of two adult monarchs I saw yesterday. This one was so intent on feeding it let me army crawl to within a foot or so of it for a photograph.  Its faded color and rough-looking wings make it clear that it’s part of the migratory population that overwintered in Mexico.

While it’s been really interesting to see these monarchs show up early this spring, we’ve also seen some first-hand evidence of why we’re further north than those butterflies usually come to breed.  First, we were worried the butterflies wouldn’t find places to lay their eggs because the milkweed hadn’t emerged when they arrived.  Then we worried that caterpillars hatched out on those tiny milkweed plants might run out of food.  Now we’ve seen a frost and cold rainy weather that appears to have been hard on both caterpillars and milkweed.  Our prairies aren’t exactly giving those ambitious migratory monarchs a warm welcome.  Hopefully, we’ll see at least a few caterpillars turn into adults from this first generation, and their cousins further south will have better luck.  If so, we’ll see our regularly-scheduled influx of monarchs in a few weeks.  By then, we should be ready for them.

P.S.  Let’s just take a moment to appreciate the incredible journey the monarch in the above photo has made…  It hatched out of an egg late last summer, maybe even in Nebraska, and although its parents had been born near where it was born and hadn’t migrated anywhere, this one somehow knew that it needed to fly south.  Not only that, it knew to fly to a particular small spot northwest of Mexico City.  It somehow successfully navigated and survived the trip there, survived the winter with a horde of others like it, and then this spring, traveled about 1500 miles back north to get to the dandelion I photographed it on.  It’s a friggin’ butterfly, folks!  It’s just an amazing world, isn’t it?