Annual Cicada

I’ve been hearing the buzz of summer Cicadas for several weeks.  Periodic storms strip the trees of spent nymphal skins, but the continued emergence of adult Cicadas return those decorations to the tree trunks.  Annual Cicadas stage an emergence every summer and often go unnoticed because their song is such a familiar part of the summer experience.  If their song was removed from the summer orchestra, I don’t think the Katydids and Crickets would be able to fill the void.

Cicadas are fun to watch, but they are often hard to get close to.  I think it was just coincidental that I looked up from examining the shed skin to find a Cicada in the branches above me.  I expected it to start singing.  Instead, it moved slowly up and down the length of a dead cedar branch.

Occasionally it stopped and appeared to hug the branch.  The bright background of the sky and my position on the ground made it difficult to see any details of what the Cicada was doing.  Fortunately, the cedar had some stout branch stubs near the ground and I was able to reposition myself upward to a better vantage point.

On closer examination I could see that what I thought was a back leg was actually the ovipositor, AKA egg laying tube.  From where I was perched, it looked as though the Cicada was depositing eggs into the dead cedar branch.  I’ve seen many egg laying Cicadas and they do lay their egg in small diameter tree branches, but I have never seen them use anything but live branches.  Maybe I still wasn’t close enough to properly interpret what I was seeing.

My next step up brought me close to level with the strange bug.  I watched for quite a while and the Cicada was indeed laying eggs.  The white material rising from the branch just below the ovipositor is wood material loosened by the egg laying action.  Eggs are laid in the slit of a branch and I always thought live wood was used because it was softer and provided the proper moisture conditions.  Since the newly hatched nymphs fall to the ground and immediately burrow in search of roots upon which to feed, it seemed that there was a definite survival advantage to be had by laying eggs in a living branch which most likely would be in a position above living roots.

In this case, despite being a dead branch, there are plenty of live roots down below.  I always enjoy making observations that go against what I’ve read or been taught.  It’s something that happens quite frequently.  The problem is that there is very little known about the life histories or behaviors of most animals.  It seems that pest animals are those most thoroughly studied and most of that was in an attempt to learn how to kill them.  Anyone who takes the time to look, will probably see some behavior that is not documented.  It’s a lot of fun.

Flowers and Insects

Summer is a time of flowers and insects. Everywhere you look there’s an abundance of life. The entrance to the trail is flanked by nine foot tall Ironweeds and Wingstem. The plants lean in to the open area created by the trail and crowd the pedestrians.

A cicada buzzes away among the Ironweed blooms. I think Ironweed is one of the most spectacular of the summer blooms. I was once in a field with someone who asked me how to get rid of Ironweed so they could grow wildflowers. I just bent down one of the Ironweed stalks and stuck the flower head in their face.

Many of the Wingstem flowers are too high to see. I’ve seen blooming Wingstem range in height from one foot up to ten feet depending on the soil and growing conditions. When I first saw tiny Wingstems, I thought I was looking at a different species. It increases the chances of species survival when species growth pattern can adjust to its environmental conditions.

When Wingstem grows alongside other flowering plants, many of the pollinating insects tend to pass it by. The plants always produce an abundance of seed, despite these low insect visitation rates. This bloom is definitely not for people who like symmetry in their flowers. The flowers of the central disk always seem to open in a lopsided manner and the rays are usually unevenly sized and randomly scattered around the disk.

A couple of weeks ago I was wondering where the Robber Flies were. Now their numbers have surpassed even last year’s abundance. This individual decided to use my pant leg as a perch while it consumed this small fly. It didn’t seem much disturbed by my walking around and stayed with me for quite a while as I photographed flowers.

This pair is busy making more Robber Fly food. These look like Picture-winged Flies, but they could be a type of Fruit Fly. The differences between these two groups are in wing vein patterns and other small characters that can’t be seen in the photo.

Orange Coneflower, Rudbeckia fulgida, is sometimes referred to as Brown-eyed Susan. This is one of my favorites. It’s an extremely hardy perennial that spreads easily by seed. The blooming season runs through the summer and up until heavy frost. Orange Coneflower is a favorite of many species of insects and always has something interesting crawling around on its flowers or leaves. I’ve scattered a lot of this seed around the field and now have an abundance of this plant.

Annual Cicada Nymph

By the look of him, this could be the original mud bug. It seems reasonable to assume that a layer of drying mud could cause mobility problems for your typical insect and this guy is certainly well coated. He seems to be doing fairly well considering this is his first time above ground since hatching.

This is an Annual Cicada nymph and I found him stumbling across the trail yesterday evening. He’s been below ground for the last several years living on sap from tree roots. He won’t be wearing this mud coat for very long. By morning, he’ll have shed his exoskeleton and joined the ranks of adult cicadas buzzily calling from the treetops. The muddy skin will be left drying on a tree trunk.

That long tube is the tool with which the cicada nymph extracts sap from the roots. It may take three or more years before the nymph has reached the stage where it will leave the ground and transform into an adult.

Annual cicadas emerge from the gound over a period of several weeks during the early summer. They are never very abundant and it’s unusual to find an emerging nymph.

The nymphs are not highly mobile below ground. In order to move, they must tunnel. Those strong front legs are the burrowing mechanism. Different stages of the nymphs life find it at different depths in the soil, but it always stays near its food source. I’ve occassionally unearthed nymphs and have never found signs of any type of tunnel system. It’s as though the nymph closes the tunnel behind itself as it moves on and only maintains a small chamber in which to exist. When I was young, I always associated the finding of a cicada nymph with good luck. At least at the moment I found the nymph, I seemed to be pretty lucky.

Cicada Damage

Last year, the Seventeen Year Cicadas emerged at Blue Jay Barrens. I enjoy the couple months of cicada activity. My only concern is the damage that occurs to some of the oaks growing in the open prairies. These trees are cicada magnets and seem to receive an unfair percentage of cicada egg laying attention. Trees are showing a lot of brown where cicadas killed the branches. The female cicada splits the young tree branches and lays eggs within. This causes the branch to dry out and die. The weight of the leaves on the branch causes it to break and hang down in a display known as flagging.

Most of the oaks found in this part of the prairie are Blackjack Oak, Quercus marilandica, the host plant of the Edwards’ Hairstreak Butterfly. No need to tell me I’ve mentioned this fact before. I’m aware that I sometimes repeat things many times. But I do become concerned about the oaks, because damage to the oaks can mean damage to the butterfly population and I like those butterflies. Seventeen years ago the damage was much more extensive and the Edwards’ Hairstreak population was greatly reduced. It took several years for the butterfly numbers to recover.

Most of the oaks are small and can suffer considerable damage.

Here’s typical damage done to the small twigs. This type of damage usually causes the branch to die right away.

This is damage done to the main trunk. The trunk was thick enough to survive the initial damage and is healing nicely. Although this type of damage doesn’t kill the branch immediately, it causes structural damage that will most likely cause the trunk to break at this point several years from now.

Small trees are favored for feeding by the Edwards’ larvae. Maybe the cicadas actually keep the trees at a small size to the advantage of the butterflies. It doesn’t really matter. All I can do is observe and hope everything works out all right.

This young lad has lost over half his top growth. You can see the reddish colored new growth beginning near the ground.

This tree is left with almost no leaves. Some leaf loss is the result of cicada damage. Most of the leaves that did grow this year were eaten. You can see just a few places where the tree is any leaf growth. Cicada damage and defoliation combined with shallow soil and dry conditions may mean the end to this tree.