Wednesday, October 31, 2012
Ten more signs that winter is coming.
Well, the temperature is a rather obvious sign. We have a few mornings now when we have waked up to temperatures in the 30's. That's been mixed in with some stormy weather, and we have now not seen our last remaining Long-tailed Skipper for several days. Supposedly the temperature will be back in the 70's later this week, and that will be the test to see if it is still around. Even if they are now all gone, a couple of weeks ago I achieved my goal of photographing two at once in the same picture. As I modestly reported to my friends, it was the first time in the three billion years of life on earth that anyone had ever photographed, in Arkansas, two Long-tailed Skippers in one picture.
Long-tailed Skippers began invading Arkansas in mid-August, so I suppose I can't use them as a sign of impending winter, which is my theme here. But late in the year many butterflies do begin moving around, so that it is a good time of year to begin looking for unusual species. Species we have noticed in the last few days moving in from the west, are Funereal Duskywing, a flat-winged skipper recognizable by the white border to its hind wings, and the beautiful Reakirt's Blue, which is very scarce here on the eastern side of the state and always a treat to find.
These are obvious signs of winter approaching. Some others are more subtle. For instance, if you have been looking carefully at grasshoppers all summer, you will notice now that the females of some species have grossly bloated and distended bellies, packed to bursting with eggs that they will soon be depositing in the ground.
Even more grossly, towards the end of the year male grasshoppers get the munchies, and while they are in the act of mating they begin eating the female's wings. This poor female has lost a leg somewhere along the line and can no longer hop. Now she can no longer fly. She still has eggs left to lay.
If you have been observing the various species of Polistes paper wasps in your garden during the year you will have noticed that during October they reached the point they were aiming at all year, and that is, they began producing a sexual generation, the males and females (virgin queens) that will create next year's nests. The males are easily noticed because they have white faces.
The queen and workers of this year's nests will all die not long after they have produced these sexuals. The next event, which you can see happening already on the sunnier calmer days of late fall, is that the virgin queens will appear, often in large numbers, outside old barns or hollow trees or roofs and attics they can get access to, looking for a place to hibernate this winter. That's where the white-faced males will be waiting to waylay them. So that as in the song in Shakespeare somewhere, the maids who (tried to) go in the door will come out the door as maids no more.
Having finished their vital work the males will all die (males never live very long among the bees and wasps), the impregnated females will hibernate all winter (actually on warm sunny days in winter they often come out in large numbers and perhaps get a drink somewhere) and emerge next year to start up new nests. But right now on sunny days the scene outside a popular hibernation site is quite chaotic with males of several species waiting for and attacking queens of every species.
For those insects not flying south or going into hibernation, there is sort of a general die off which, because they are so small, and so invisible lying in the dried leaf litter, you might not notice. But we have a white concrete driveway which shows up insects from a distance and I notice more and more insects sitting on the driveway, walking around morosely, ending up dead the next day. Here's a little gleaning.
I noticed today another rather grim end-of-season example. Argiopes, the big golden garden spiders which are usually very successful in our yard, this year for reasons we don't really understand, had a miserable year and we thought they were entirely gone. But we have just found one big female made it through until now. But something terrible happens to them at this time of year. What I have heard is that spiders have a defined amount of web in their systems, and when that runs out, they're out of luck. I don't know if I quite believe it, but I do know that at a certain point they stop repairing their webs daily, or if they try to repair them, everything comes out wonky. Here is our one surviving Argiope.
Not all end-of-season things are grim. For some insects, this is their time, their chance at a life in the sun. A few blogs back I showed pictures of Laphria affinis, the big predatory fly that is such an expert mimic of bumblebees. This robber fly comes out later in the year than just about any other Arkansas robber fly, and lasts longer into winter than any other. Just seeing this fly is a sign of the season, but a happy and entertaining sign. I have on two different years found them still flying on November 30th. This year, if the weather is mild, I will try once again, to see if I can find one on December 1st. Another species of robber fly, Nicocles pictus, comes out in mid February. If I can get Laphria affinis into December, I can then boast that Arkansas robber flies are out every month except January, which is pretty good for a state this far north. If I find one this year, I will report it here, and you can share my excitement.
But, before I got distracted, I meant to say something more about the life history of this species. They are closely connected to pine trees, and are only found where pine trees are numerous. The best way to find one is to look for a place where there was a blow down of pines several years ago, and the fallen trunks are decaying. The larvae of Laphria affinis feed on the beetle larvae which feed on decaying pine trees, and the female Laphria lays her eggs in the tunnels of these larvae. The male takes over a promising tree and defends it against other males and waits on his tree for the female to come by and lay her eggs, and he makes sure that he mates with her first. Here is a picture I took yesterday of a male waiting alertly at his log, and all the colors of autumn are behind him.
Last minute news item: While I was writing this, I went out and checked, and our Long-tailed Skipper is back.