Cicadas

If you are from the south you are probably familiar with the sound of Cicadas in the late evening. Around here we called them dry flies, don't ask me why. I guess it could be because they look like a huge fly. In any case, there are a lot of them around here and they do make a lot of noise on summers evenings. It seems like forever that I knew what the adults looked like, and I knew they came out of the empty brown shells that you found on trees, brick walls, or just about anything else a bug could crawl up on. It wasn't until the summer of 2001 that I actually got to see the adults emerge from the brown shells. The picture on the left is one of the nymphs crawling up a tree in preparation for the adult emerging. This one in particular I found while he was still crawling on the ground so he had just dug his way out. The nymphs spend their life in the ground feeding off of tree roots and emerge when it is time for the adults to emerge. Some species have 13 year cycles, others have 17 year cycles. I don't know which particular one we have here, or we may have an overlap of more than one species.

After they find a suitable place to anchor themselves the shell will split just behind the head and the adult will start to work its way out. The pictures here were taken over a period of several hours, and are of a couple different individuals. It takes a long time for the adult to work its way out of the shell, and they seem to work a little bit and rest a little. When they are fighting to get out they seem to vibrate for a few seconds and then stop. I guess it takes a lot of work to get out of that shell. The one on the right has probably been at it for a while to get that much of his body out. I don't know how long it takes to get to this stage, but from this point to where the adult is fully emerged and hanging his wings out to dry takes a couple hours. It is a slow process. Most people have probably never seen this because it happens at night. I found that I could go out around 10:00 pm and catch them as they were just starting to emerge from the shell. Usually there would be several of them at slightly different stages. This was in early August and for several nights there would be half a dozen or so on this same tree a couple feet off the ground. Later it slacked off to one or two, and lots of nights none.

Last year we had a very dry summer and I noticed that there would be more shells on the tree the day after we had a rain. It's just a guess, but it seems like the rain loosened the ground up to make it easier for them to crawl out. Or it could have been other reasons, but after a rain there were more shells the next morning. After they get about half of their bodies out of the shell, maybe a little more, they get into this bent over backwards position. I must admit that the first time I saw one like this I thought something had happened to it and it was dead. There were several more on the tree and they all were more or less in the same position so I figured it must be normal. That was the first thing that I found out I was wrong about with Cicadas. I had always assumed that they would come out head first, grab on to the shell with their feet, and pull the back part out. As this picture shows, that is not how they do it. In this picture you can see that all the legs are clear of the shell, and the little green numbs about half way between the eyes and the shell are the wings. I did notice that at this stage they seem to take a long rest. There may be a couple reasons for this, and I am guessing here. After all the work to get to this point they may just need a little rest. It's also possible that they have to give some time for their legs to harden and get ready for the next stage.

Here is a side view of the adult pictured above. This picture was actually from a few minutes earlier and you can see that not all of the legs are clear of the shell. You can also see that the body just looks soft and vulnerable, not at all like the adult will later look. When I was taping the emergence I would tape for a couple minutes and then stop for a while. I didn't want to interfere with them too much, and since they come out at night they probably didn't like my bright light shining on them. But it was just so interesting to me that I had to get it on tape. Since it takes such a long time for them to complete the process I was able to capture most of it on tape by going out every 20 to 30 minutes and taping different individuals that were in different stages. It was interesting to watch them vibrate as they wiggled out of the shell, and then without noticing that they had moved out to suddenly realize that they were farther out than they were a few minutes before. It happens so slow that you don't notice it as it happens. It's only later that you realize they are farther out of the shell than they were the last time you noticed.

There is one time that they do move fast. Considering how slow the rest of the process is, this one stage can only be described as a great burst of speed. For them to be able to hang onto the shell while their wings unfold and dry, and their bodies harden, they have to grab onto the shell with their legs. Since they are hanging upside down in the bent over backwards position up until this point I was wondering how they were going to accomplish this. The individual in this picture was indeed upside down, hanging as he was on the underside of a cable. Since he was also in the bent over backwards position I was really interested in how he was going to get into the proper position. Since they had been moving so slowly up to this point I missed the burst of speed as he swung into this position, though I did see it. In less than a minute, probably only a handful of seconds, he curled his body forward, grabbed hold of the head of the shell with his legs, and pulled the remaining part of his body out of the shell. It was quick, and definitely not a time to make a mistake. If he didn't grab hold of the shell with his legs before the rest of his body came out he would end up on the ground below. As you can see, all went well. His wings are just now starting to unfold and he will stay in this position for maybe a couple hours. Over this time his wings will unfold and dry out, and his body will harden a great deal. I guess this is the easy part since all the hard work is done. Now it's time to rest while the wings dry.

Sometime later this is what out little friend will look like. The wings are fully spread and seem to be about dry. I don't know exactly how long they take to dry to the point that the Cicada can fly, but they are always gone before morning. I have read somewhere that it takes a couple days for the body to harden completely so they probably make a short flight up into a tree to hide while that happens. At any rate, this is the last view I have of them on the night that they emerge. I have seen them hang in this position for a couple hours as the wings unfold and dry, and I try not to bother them so they can go about their own business. The summer of 2001 we seemed to have shells in the yard than usual. In one area around one particular tree it seemed that they were everywhere for several weeks. A couple weeks later I discovered that they were using another tree to crawl out on, but it is covered with Virginia Creeper and I didn't take any pictures. All in all I found it very interesting to witness the emergence of the Cicadas from their shells. Knowing how something happens just isn't the same as watching it happen. I hope you found this interesting. Perhaps some summer night, just after dark, you'll take a flashlight and go exploring in your backyard.