Awesome Arachnids

She asks me to kill the spider.
Instead, I get the most
peaceful weapons I can find.

I take a cup and a napkin.
I catch the spider, put it outside
and allow it to walk away.

If I am ever caught in the wrong place
at the wrong time, just being alive
and not bothering anyone,

I hope I am greeted
with the same kind
of mercy.

~Rudy Francisco

I led a full moon walk this past week at Mason Farm Biological Reserve, a wild and wonderful tract managed by the NC Botanical Garden, only a mile or so from my office. I love being outside at night, hearing the night sounds, and trying to catch a glimpse of the creatures that make darkness their time of choice. The night before the hike, I walked alone along the trail at Mason Farm, looking for things to highlight and reacquainting myself with the brilliance of an almost full moon. A variety of night sounds greeted me as I walked in silence – the startling snorts of alarmed deer, a solitary hooting of a Barred Owl, a lone tree cricket…but the most magical was when a group of Coyotes initiated their yipping and howling as the moon rose above the tree line. Though it lasted less than a minute, it is a sound that sticks with you (and might even raise the hairs on the back of your neck a bit). Chilly night temperatures, combined with recent floods, seemed to reduce the number of night-time invertebrates that were out and about.

Ther Laugher Moth larva on oak

A fuzzy larva of The Laugher Moth feeding on oak, my only glow-in-the-dark caterpillar this past week (click photos to enlarge)

I searched with my ultraviolet flashlight for caterpillars, hoping to find some of my favorite slug larvae species, but came up with only two fuzzy larvae of The Laugher Moth. But there was one group well represented and quite noticeable, if you know how to look…

Carolina wolf spider 1

Carolina Wolf Spider, Hogna carolinensis, out and about along the edge of a field

Yes, that’s right, and somehow theme-appropriate at this time of year, spiders! On my pre-trip, they were everywhere, especially concentrated along the habitat edges (boundary between forest and field) and along the stream banks and swamp edge. If you don’t know, you can “sniff” spiders by holding a flashlight near your eyes or nose (or wear a headlamp) and scanning your surroundings. On almost any night from March through October, you are likely to see what look like dewdrops scattered across the ground. These are most likely spider eyes reflecting your light back to you (some may be dew drops if it is damp). If you are just holding a light down by your side, their reflection comes back at that level and you probably can’t see it. That’s where the sniffing part comes in. You tell your group you smell a spider. Since most people don’t usually walk around with their flashlight up near their eyes, they can’t see the eyeshine. On my program walk, I was able to run about 25 feet over to a tiny spider on a tree trunk by keeping my light on it to see its eyeshine. Of course, you always share that trick with your participants so they can see for themselves the incredible abundance of these spiders.

Hunting spiders, like wolf spiders, have a reflective layer in their eyes that bounces the light around so that there is a better chance to have it absorbed by the rod cells that help them see in low light. This is similar to what happens in the eyes of nocturnal vertebrates like deer and cats. One of the larger species out this time of year is the Carolina Wolf Spider which generally hides in underground burrows during the day, and then emerges to hunt prey at night. Females carry their egg sac off the tip of their abdomen. The baby spiders hatch and ride on the mother’s back for a week or so until they molt and then disperse.

Rabid wolf spider

A large, female Rabid Wolf Spider, Rapidosa rapida

Another large, and quite common, ground hunting spider is the oddly-named Rabid Wolf Spider. Its common and scientific names come from its rapid movements, not any ability to carry a mammalian disease. The bold stripes on the cephalothorax (the front body part that is sort of a head and thorax combined) are diagnostic of this species (along with some more subtle features). Males are distinguished by their smaller size and by the first pair of legs being black.

marbled orb weaver

A Marbled Orb Weaver, Araneus marmoreus, in her web

There are relatively few web builders left out in the fields and woods this late in the season, but there is one notable exception, the Marbled Orb Weaver. This distinctively colored (yellow or orange abdomen) spider can be found in woods and along field edges into November. During the day, the large female hides in a folded leaf retreat along the edge of her circular web. She holds a line of silk attached to the web to detect and struggling prey. At night, they are more typically found perched in the center of the web. Their color scheme and occurrence through late October has given them another common name, the Halloween Spider. Web-builders typically have no eyeshine since they rely less on vision and more on vibrations of struggling prey in their web to obtain their meals.

Dolomedes spider

A huge Dark Fishing Spider, Dolomedes tenebrosus, on a tree trunk at the edge of the swamp

The best spider find on our tour was made by one of the participants as we stood near the closed portion of the trail through the swamp. Hurricane Florence took out the boardwalk through this section so you can no longer walk the circular route. But, perhaps because of that pause, we got to see one of our most spectacular spiders, a very large Dark Fishing Spider. This large female would almost fill my palm. They are frequently found head-down on tree trunks (like this one) near water, but can occur quite some distance away. I have them in my workshop and frequently find their sheds scattered among my scrap wood or tools. There are other members of this genus that are more frequently found on and/or in water (e.g. the Six-spotted Fishing Spider) where they actively hunt for creatures that fall on the surface, or those that live just beneath (like aquatic invertebrates, tadpoles and even small fish). Female fishing spiders carry their egg sac beneath them, hanging onto the silken bag with their chelicera. When the young hatch, she creates a nursery web for them where they stay for a short while before dispersing.

bread

Even the bread, Greatbreadus multigrainiia, at the Farmer’s Market is arachnid appreciative

I had a chance to write up some of this on Saturday, but not before I made my weekly trip to the Carrboro Farmer’s Market. There, I spied one more thing to add to this post – a loaf of beautiful bread from Chicken Bridge Bakery. So, whether its a graphic on tasty bread or an eight-legged critter on the trail, take the time to learn more about these awesome arachnids. If you want to learn more and see some incredible photos, check out some of the scientists I follow on Twitter – TurnFear2Fascination, Catherine Scott, and Thomas Shahan…you, too, will learn to appreciate these amazing creatures even more. Happy Arachtober!

Sweeping Grass and Rolling Logs

The art of teaching is the art of assisting discovery.

~Mark Van Doren

We had an adventure on one of the last weeks of summer camp at the Garden. It was all about discoveries – trees, dragonflies, aquatic macroinvertebrates, field and forest insects and animal tracks and signs. A highlight for me was sharing the incredible diversity of Mason Farm Biological Reserve with those budding naturalists. We sampled both field habitats and forest edges using various techniques from sweep nets (swinging a mesh net back and forth through tall grasses and examining your catch) to log rolling (gently turning over downed logs to check for decomposers and other critters).

Phidippus clarus, Brilliant Jumper, good eye view

Brilliant jumper, Phidippus clarus, in a sweep net (click photos to enlarge)

The kids were excited about their finds as they swept the nets back and forth along the edge of the meadows. I was so busy helping them catch and identify things I didn’t have much time to photograph anything, but when one camper saw a tiny jumping spider in his net, I had to grab the camera. I have a weakness for jumping spiders and their bold colors, huge eyes, and “inquisitive personalities”.

Phidippus clarus, Brilliant Jumper, looking up

Brilliant jumper right before it did just that (up onto my lens)

I later identified it as a brilliant jumper based on the green chelicerae and the orange pattern on the abdomen. I shot several images as it crawled about the edge of the net, pausing frequently to stare up at my camera gear looming overhead. It finally did what they often do, and leapt up onto my lens, ending its photo session.

Rabid wolf spider, Rapidosa rapida?

Rabid wolf spider, Rabidosa rabida

As we walked along the forest edge, someone spotted a huge wolf spider. I bent over for a closer look and a quick picture of its enormous (and numerous) eyes. I’m not sure how the common and scientific names came about (rabidus is Latin for wild, crazy, raging), but maybe some early arachnologist laid down and looked into the face of one of these huge spiders and felt a slight twinge just as I did.

We showed the campers the proper technique for rolling a log (gently roll it toward you so that any larger critters can escape away from you instead of coming at you).

Psallis beetle in gallery in log

Passalus beetle, Odontotaenius disjunctus, in one of their tunnels in a log

One log revealed a treasure trove of beetles – some adult passalus beetles (in the family Passalidae), and several large beetle grubs. These common large beetles are also called patent leather beetles, horned beetles, horned passalus beetles, bess beetles, and many other common names,

unid beetle grub;  not a psallis 1

Large beetle grub under log

The first two grubs were huge, curled in a C shape under the log. I did a quick glance and told the excited kids those were probably the larvae of the passalus beetles and bent down to pick one up. I then noticed another larva crawling nearby. It was slightly slimmer and was actively moving instead of being curled up.

Psallis beetle grub on finger for scale

Another, more slender, beetle grub

At first, I assumed they were just different ages of passalus beetle grubs. I remembered reading that their larvae have a reduced pair of legs used for stridulation (making sound by rubbing one body part against another, in this case, the reduced leg against the adjacent larger leg).

Unid beetle grub; probbly not a psallis

A closer look at the first grub shows 3 pairs of legs with the first pair slightly reduced

I always had wanted a photo of the reduced pair of legs (it’s what we nature photographer types do) so I flipped over one of the larger grubs and took a couple of quick shots. Sure enough, the first pair of legs was smaller then the other two pair. We gently replaced that log to its original position and rolled another. More beetles! And something else…

Psallis beetle pupa

Beetle pupa

There were a couple of beetle pupae under the log (I assumed they were passalus beetles). This was really cool as I had never seen large beetle pupae before. One was attached to the underside of the log in what looked like a chamber made of wood debris and maybe beetle frass.

Immature psallis beetle

Juvenile passalus beetle is brown in color

There was also a brown-colored passalus beetle. These are juveniles and they will gradually darken to black as they mature (I wasn’t able to find how long this takes).

Adult psallis beetle

Adult passalus beetle is black

Passalus beetles are fascinating critters and a frequent live animal used for environmental education demonstrations. They are one of the few beetles that are social and tend their young. They feed by chewing galleries through the soft wood of downed trees and then re-ingesting their frass after it has been colonized by bacteria and fungi. They also feed this mixture to their larvae. One way they maintain this social structure is through a complex communication system created by stridulation. Adults stridulate by rubbing rows of spines on the undersides of the soft, flying wings (the membranous wings hidden under their hard outer wing structures – the elytra) against a hardened textured area on the top of their abdomen. As I mentioned earlier, the larvae can also make sounds, and these are believed to be important not only for social communication, but also defense against predators. Pick a beetle up and hold it close to your ear, and you are likely to hear some squeaks (click this link to hear passalus beetle stridulation). This same reference states that passalus beetles have 17 known audio signals for both adults and larvae, making it the most elaborate sound communication system known for any arthropod.

I was all set to write up a blog post when I double-checked my information on the life cycle using various online resources. Then it happened…I began to think I had made a mistake in my identification of the large grubs. I found a reference that stated passalus grubs have a reduced pair of legs, but it is the third pair, not the first, as I had seen on the large grubs. Plus, it said these small legs were so reduced as to be difficult to see. Dang, I had to go back and check out those grubs again. Well, as luck would have it, it rained a lot the next day and the creek rose making it tough to drive across to Mason Farm. Things were busy at work that week, but as I was walking on our nature trail one afternoon preparing for a program, I saw a log off the side of the path. I walked over and flipped it, hoping to find…

Psallis beetle grub and adult

Passalus beetle adult and larva

There was an adult passalus beetle and a large slender grub! There were actually a couple of grubs under that log, so I gently grabbed one and flipped it over to look at its legs.

Psallis beetle grub showing reduced leg

The third pair of legs is greatly reduced on this grub

Yes, indeed, that third pair of legs is reduced and very difficult to even see on a passalus beetle larva! So, I had been wrong in my ID on that first quick glance. Those large grubs are most likely the larvae of some other beetle, perhaps a stag beetle. Not only did they not have the greatly reduced third pair of legs, but they were all curled into a C shape. Passalus grubs are usually straighter in posture and more slender. I’m not sure about the pupae, as I didn’t manipulate them to see all sides, but I think they still may have been passalus pupae. It was a good reminder that I need to make careful observations and to double-check my information. Of course, now I want to go back and check on the pupae and see if they are still there, and, if so, maybe keep one to see what emerges. It also showed me that there is always something more to learn about even the common creatures we share our world with, and that learning truly is a life-long endeavor.