Monday, April 27, 2015

Paying for the click

This weekend, I was trying to evade the mosquitoes swarming around me when I saw a much larger insect flying slowly down the trail.  It soon landed on a vine a short distance away and I recognized it as a click beetle.

A Texas click beetle (Alaus lusciosus).
Although this click beetle did not have the glowing spots that had first made me fascinated with click beetles, its prominent eye-spots, large size, and loud clicks still made it very impressive.

The big spots on top of the beetle are not its real eyes.
For a demonstration of the clicking behavior, watch the video below.  If you happen to find a click beetle yourself, I do not recommend that you attempt to provoke it into clicking.  As I discovered somewhat painfully, when clicking fails to deter the harasser, the beetle may resort to biting.

If you watch the slow-motion part of the video carefully, you can see that the 'jump' is not caused by the beetle snapping back against my hand (as I had initially thought).  Instead, the beetle lifts its head away from my hand and then the rest of its body just pops into the air.  The key to the click and jump is the spine that extends down from the underside of the head.

The underside of the Texas click beetle.  Note the spine used in clicking and the sharp mandibles used in biting.
The beetle produces the click by first catching the end of the spine into a notch, which prevents the beetle from moving as it contracts a large muscle that connects its body segments.  Then, when the spine slides out of the notch, the energy in the muscle is rapidly released, propelling the beetle into the air.

Explore some more: The Click of the Click Beetle (a full explanation of the physics of the click)

Monday, April 13, 2015

Going to ground, part two

Goatweed leafwing butterflies may not be as bright and conspicuous as many other butterflies are, but they do not look much like leaves either.

A goatweed leafwing (Anaea andria) perched on a branch.
At least, they are not very convincing as leaves when they are sitting in trees (which they often are).

A goatweed leafwing butterfly hanging upside-down from a branch.
It is a completely different matter, however, when the goatweed leafwing sits underneath a tree in the leaf litter.  There, it becomes very difficult to distinguish from the surrounding leaves.  To see how well-camouflaged the goatweed leafwing can be, try finding it in the three pictures below!

Can you find the goatweed leafwing?
I promise, there really is a butterfly in each of these pictures.

The butterfly moved.  It might be slightly easier to find this time.
When I was taking the pictures, I had the advantage of seeing the butterfly land and then walk around.

The butterfly moved again.  It should be easiest (but maybe still not easy) to see in this picture.
To see the butterfly locations revealed, go here.  I've edited the photos to make the butterfly pop out from the background.

Monday, April 6, 2015

Going to ground, part one

The butterflies visiting the lantanas were quite conspicuous as they moved from flower to flower drinking nectar.  Nevertheless, if threatened, they could quickly vanish from sight.  As I described before, the cloudless sulfurs often disappeared by flying off into the woods.  However, sometimes they just landed on the grass -- and were gone.  Despite the fact that cloudless sulfurs are yellow, I would completely lose track of them in the grass if I took my eyes off them for a moment (which always seemed to happen when I tried to approach slowly and without stepping in a fire ant nest).

I frequently step in fire ant nests.  Fortunately, if I am wearing my rain boots, I tend to notice the ants in time.  Unfortunately, I am not always wearing my rain boots.
The boldly-colored red admirals could also camouflage themselves on the ground...

A red admiral (Vanessa atalanta) sunning on the ground. closing their wings together and showing only the mottled, brown undersides.

The red admiral with its wings closed.
For the next post, be prepared to put your hidden-butterfly-finding skills to the test!

Wednesday, April 1, 2015

A tough egg to crack

Last summer, I kept seeing song sparrows and gray catbirds coming in and out of a dense patch of rosebushes.

A song sparrow (Melospiza melodia) emerging from the rose bushes.
I guessed that they had built nests somewhere deep inside.  Although I eventually found the song sparrow nest, I was disappointed that I could not locate the catbird nest.  So, as a surprise, my mother put a wooden egg in an old nest and left it for me to stumble upon.

A large, blue egg in a nest.  (Not a real egg.)
 However, something else found the egg first.

When I heard crows squabbling, I looked out and saw that one of the crows was sitting on the ground by the rosebushes and attempting to eat what appeared to be a gray catbird egg.  Of course, not knowing that a wooden egg had been placed outside just minutes before, I assumed that the crow had found and raided the catbird nest.  The truth only emerged when I shared the sad news about the catbird nest with my mother.  She quickly led me to the nest where the wooden egg had been. As she had suspected, the nest was empty.  When the wooden egg finally reappeared in the yard several days later, it was in splinters.  (The photograph of the egg in the nest above showed a reenactment using a spare egg.  We immediately brought that second egg back inside!)