Tuesday, April 2, 2013

I'll count this as spring.

Flowers are blooming and birds are singing, and between the days of rain and gloom there are some warm sunny days that we are very grateful for. The other day I was looking at the plum tree in our front yard and saw that the very first flower was blooming. Here's a picture of it with a goldfinch mostly through its change from dull winter greens to bright summer yellow.

Here's the same tree (probably different bird) four days later.

Also the butterflies are starting to appear. Yesterday was fairly warm and sunny, and we went up to Scatter Creek WMA in Greene Co. and walked some of our favorite trails. We saw some half dozen species, mainly Mourning Cloaks (about twenty), which were so abundant last year that everyone remarked on them, and this year they are if anything even more abundant. But there were also bright orange Goatweed Leafwings, and rather yellow Orange Sulphurs and black Juvenal's Duskywings and blue Spring Azures, and white and orange Falcate Orange-tips (they were teeming; we saw 20+).

But best of all we saw Henry's Elfin, best because it is tiny and special and only comes out at this time of year for a brief time and if you miss it, you have missed it until next year. So there is always a bit of relief when you see that this year, anyway, you didn't miss it. They always land with their wings folded straight up, so that you only ever see the underside of them. Here's a picture of the butterfly from the right side, followed by a picture from the left side. On the left side its wing is partly folded over, so you get a glimpse of the interesting coppery color of its upper side.

The spiders, that we are going to try to learn this year, are suddenly coming faster than we can keep up. But here's a particularly interesting one I can share with you.

This is what we saw first, this 3-4 mm long creature walking steadily in a straight line across the driveway.

We had to look very closely to realize that it was not an ant but actually a tiny ant-mimicking jumping spider, and that the antennae it was waving in front of it were in fact its first pair of legs. Its name is Synemosyna formica. Here is a picture of it blown up so you can see it in more detail.

There are the fake antennae stretched out and waving in front. Note the black line going up the inside of the leg, so that what you see is more like a slender black antenna than like a fat leg. Now note the hind end. Most ants in warmer parts of the country don't have a simple abdomen. Instead the abdomen is constricted into two or three bulges, technically called gasters. This spider has two fake gasters. The antennae, the gasters, indicate to me that whatever creatures the spider wishes to fool are very good entomologists, so the mimicry needs to be detailed and exact. Now, why does a spider want to look like an ant? One theory is, ants are full of formic acid, and therefore most things don't want to eat them. A second possibility is, that the spider itself DOES want to eat ants, and its disguise might allow it to cozy up to a juicy real ant and catch it for dinner.

There is another mystery about this spider. Male spiders, when they are fully adult and ready to mate, have palps (the little leg-like things on either side of their mouth) that are swollen at the ends, carrying a lot of complicated sexual apparatus in them. Before mating, the male loads the palps with his sperm, and then uses them to place the sperm inside the female's sexual opening (which is located towards the front of the abdomen on the underside). The mystery here is, the spider in this picture is a subadult. It needs to shed its skin one more time before it is a mature adult, so even if it were a male, it shouldn't have swollen palps yet. But in fact, it is a subadult FEMALE, yet it has these bright red palps that it shows very prominently.

Here is a (not very good) picture showing the palps, which are the right shape for male palps, but don't seem to contain all the complex machinery. When she sheds into adulthood, she won't have these swollen red palps, but very modestly swollen and barely noticeable black palps (adult males have big complicated black palps which they use to wigwag at promising females, showing them their stuff).

Now I could easily explain the purpose behind all these mysteries, but she's really getting annoyed with me following her around, so I'll just let her go and say goodbye.

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