spiders

Snow spiders

Earlier this week, on a mild afternoon, I was working on my computer while Dan had taken Raven out for some exercise. I was startled by a sharp rap on my window. When I peered out, Dan was gesturing for me to come down: he’d found something he thought I might be interested in.

It turned out to be a spider, curled up on the surface of the snow. It was less than a centimetre long with all its legs tucked in to its body, and how he spotted it I don’t know. It was out in the middle of the milkweed fields, so I can only presume that it came out of one of the milkweed pods, or maybe up through a hole in the snow at the base of one of the stems. It would have been a long way for it to walk from other potential origins.

I started out trying to ID it by going to BugGuide.net and doing a search for “snow spider”. And lo and behold, there it was! Along with quite a number of other spiders on snow. I’m fairly certain this is a Ground Spider, family Gnaphosidae, maybe in the genus Gnaphosa, and could possibly be G. parvula. I make this identification based on the dimples/pale spots in the slightly-flattened top of the abdomen (others I looked at had rounder abdomens and/or lacked dimples). Another possibility that occurs in our area is G. muscorum, except that’s supposed to have a pale patch at the front/top of the abdomen. Really, though, I’m waiting for its identification by an expert at BugGuide.

In the meantime, while looking up whether Gnaphosa sp. are even active in the winter, I found this pdf article called the Phenology of Winter-active Spiders. The opening sentence states that there are 54 species of winter-active spiders in southern central Canada (the author was from Manitoba) and the article discusses the life cycle of each. The only Gnaphosa he mentions is G. muscorum, and all of his specimens for the species were collected in May-June-July (though all the species in his report are ones that are supposed to be active in the winter). So I may have to wait for an ID on BugGuide.

I ran off a few photos of Dan’s spider, then started walking back to the house. As I returned, I kept an eye on the ground, to see if any other critters might pop up (recalling also the caterpillar from a few weeks ago). No caterpillars, but I did find a second spider. Assuming it was the same as the first, I just ran off a few shots with the idea of posting one on the blog, following the first and saying “hey look, I found another.” When I got the photos uploaded onto my computer and looked at the spiders at about 20 times life size, I became pretty certain that they weren’t the same species. Their cephalothoraxes (the heads) weren’t the same shape, for one thing. The second one’s legs were thinner than the first’s. Hmm…

Looking more closely at my selection of “snow spider” results, I spotted this species in there as well. This is a Thin-legged Wolf Spider, belonging to the genus Pardosa. There are two genera that look very similar, and can be told apart by the presence or absence of a dark V on the cephalothorax. It’s absent on this one, therefore it’s Pardosa. The pdf mentioned above also had two Pardosa species listed. Neither of them were encountered in the winter, either.

This spider wasn’t found out on the snow, it came in on a piece of firewood. Dan also found this one and called me downstairs to see if I was interested. It’d probably been quite happily tucked away in the stacks of firewood in the garden “shed”. Very long-legged and delicate-looking, this is a Long-bodied Cellar Spider, Pholcus phalangioides, and is one of the most common household spiders. Originally native to the tropics, it’s now found in much of the world. It’s often one of the most abundant in any given house (or cellar, or woodshed). They build webs, and when disturbed will shake their web violently in an attempt to startle or confuse predators.

Their long-legged nature really only confuses them with one other type of arachnid, the harvestman, frequently called “daddy-long-legs”, although it turns out that both of these arachnids are sometimes known by that latter name. The specific name of the cellar spider, phalangioides, originates from the roots Phalangium (the genus containing harvestmen) and “-oides” which is Greek for “similar to” or “resembling”.

Cellar spiders are great for pest control. In particular, they will prey on other spiders, often species that are much bigger than they are. I found one comment on BugGuide suggesting that this would be a useful thing for folks living in Arizona and other places where venomous spiders may be a consideration. Encourage the cellar spiders to set up shop and it’ll help keep your other spider populations down! When food is scarce, they’ll turn cannibalistic, feeding on others of their species.

Here’s a neat series of shots submitted to BugGuide, of a cellar spider and its prey, which the photographer unwrapped and cleaned to see what it was.

It’s a bug-eat-bug world

Over the last few weeks I’ve collected up quite a number of photos of predator-prey interactions in the invertebrate world. I’ve been doing a bit of “housecleaning” in my computer’s file folders, going back and revisiting photos I took at the beginning of June and trying to sort things out into some semblance of an organized filing system (the jury’s still out on how effective it actually is). I came across these and thought I’d throw them all into a post together.

Most of the photos could actually be “it’s a spider-eat-bug world”. Jumping spiders, such as this one, are one of the groups I see most often with prey. Perhaps this is partially because they’re one of the groups I see more often in general. Perhaps it has to do with their method of hunting (since they don’t use webs, they have to hold on to their prey).

Spiders are like flies for me – if I can put it into a general family, I feel I’ve done good. There are a few distinctive species, by by and large a lot of them look the same to me. The large, forward-facing eyes and stocky build identify it as a jumping spider, family Salticidae. My best guess for this is a member of the genus Eris, maybe Eris militaris, the Bronze Jumper, aka Bronze Lake Jumper, which seems to be a fairly common and widespread species. It’s eating a cricket. I spotted it a couple of weeks ago on an open rock at Rock Ridge.

On the same visit, I snapped this photo. It’s of an unidentified clubtail, munching away at a deer fly. The dragonfly had snagged the fly out of the air as it buzzed about my head, and then settled on the rocks only a few feet away to enjoy it. It’s too bad you can’t train the dragonflies to buzz around your head patrolling for deer flies.

This spider also has a deer fly, but it didn’t catch it out of the air. I’d been wearing that sticky tape that you put on the back of your hat, which snags the deer flies when they land on it. However, it seems to decrease in efficiency as it fills up, so I’d been pulling the caught flies off the tape and tossing them on to the rock. I can’t bring myself to crush them with my fingers, but as I pulled them off often a wing would remain stuck to the tape (it’s very effective stuff), and the spider snagged one of the flightless flies. I think it might be a type of wolf spider, many species of which are hunters rather than web-builders.

Another one of those discarded flies got picked up by this ant. The fly was easily twice the size of the ant, but she was marching along with it like it weighed nothing at all. She couldn’t even really see where she was going, and I wonder if she was following a pheromone trail or if she was just wandering blindly.

Another jumping spider, this one spotted on the trunk of a tree with an unidentified fly prey. It could be a female Maevia inclemens, Dimorphic Jumper, which seem to have that pale abdomen with two red stripes. The males, true to the species’ name, are either black or grayish, with white legs.

And the last one is of the Goldenrod Crab Spider, Misumena vatia, that has been sitting in the Allium in my garden. One day when I checked on it, she had caught something. That something was a bee, possibly a mason bee (genus Osmia) of some sort. My favourite part of this photo is that you can see the bee’s tongue still hanging out, the tapered, orange-tipped appendage hanging from its head.

Four days early

Another beautifully mild day today, with our thermometer peaking at 17 oC (63 oF) in the sun mid-afternoon (actual temperature was somewhat lower, but not by a great deal). We’ve had a string of such nice days now. It looks like after tomorrow a cold front will move in and drop temperatures down for a few days, but by this time next week we’ll be back up again. I’ve been starved for balmy, sunny weather, I’ve been soaking it in these last few days.

So has the wildlife. I’m up to 12 species of moths recorded so far this season already. This seems to me like an extraordinary number for March 17, and I’m not sure how much of that number has to do with the string of warm days (perhaps we didn’t run into that last year?), versus me actually setting up and looking for them (I didn’t try this early last year because I didn’t want to waste my time if nothing was flying, since it was more of an effort when we were in the apartment, but this year since we’re in a house I can put the light out anyway and it’s not a big deal if nothing comes), versus simply being in a great place for moths (and everything else; I love my home).

Last night I got two moths which I took photos of this morning, after holding them chilled in the fridge overnight. Rather than just setting them up on the deck railing or on a sheet of paper or something, I hunted down a dead leaf that was still in good shape as a photo base. Most were starting to fall apart, or if they were still intact, they were curled up. Finally I found one that was whole, and mostly flat. When I picked it up and turned it over, I noticed a small white speck on the underside. It turned out to be a leafhopper. I think it’s a Red-banded Leafhopper, Graphocephala coccinea, also sometimes known as a Candy-striped Leafhopper. It’s very pale, and I suspect this may be because it had just recently emerged, and its exoskeleton was still soft (the colours in insects’ exoskeletons often strengthen as the shell hardens).

Also something I noticed today that I hadn’t over the weekend was a profusion of flies. They were ubiquitous in open areas where leaf detritus had piled up in the fall, such as the edge of our driveway and lawn, or the clearings along the forest edge. I’m not positive on its ID. I think it might be a Stable Fly, Stomoxys calcitrans, which is a common and cosmopolitan species. I was able to rule out House Fly by the veination on the wings, but that was about as far as I got. Flies are a group I’m content to leave to someone else’s expertise.

Edit: Kirk suggests in the comments that this is a Flesh Fly, family Sarcophagidae. So not even close to Stable Fly. I told you fly ID is better left to the experts.

I was intrigued by the discovery of the leafhopper, and the presence of all the flies, and thought perhaps during my walk with Raven today I’d take my camera and see what other spring insects I might be able to turn up. I wasn’t expecting much – after all, it’s only March 17 and there’s still snow on the ground in many places. But I might be lucky and find one or two.

I was surprised to discover a total of 13 individuals of 7 species today. Leafhopper and flies were #1 and 2, but species #3 was the above – fire-less fireflies known as the Winter Firefly, Ellychnia corrusca. The genus Ellychnia are all diurnal, and as such lack the light-emitting organs of most other fireflies (not much point, they wouldn’t be seen). They are also most commonly found on tree trunks, and indeed these two (plus one other) were climbing up the ridged bark of a big White Pine. The Winter Firefly, presumably taking its common name from its cool-weather tolerance and early spring appearance, also happens to be the largest firefly of the northeast by almost twice as much – the large one in this photo was probably about 18mm, perhaps 5/8″.

A couple trees away, sitting on the side of a hop-hornbeam, was this critter – a ladybeetle, but not the generic orange-with-black-and-white-“head” Asian Ladybeetle that we’re so used to seeing around the house and garden. This one is actually native, and discovering native ladybeetles is such a rare occurrence for me I could count the total number I’ve seen on two hands. Surprisingly, there are actually more than 480 species in North America, so I don’t know how much of my not having seen many is simply because they’re secretive compared to the Asian invaders, or because the Asian beetles are outcompeting them. This particular one, seeming the reverse in pattern from the usual black-spots-on-red, is called the Twice-stabbed Ladybeetle, Chilocorus stigma. You can see why the species was named such, but it’s a slightly morbid name, particularly when you consider the Lady in ladybeetle was actually a reference to the Virgin Mary.

There has been a general decline in ladybeetles on the continent, and in recognition of this the Lost Ladybug Project was started in an effort to build a database of ladybeetle sightings to try to help with monitoring these species (since it’s really hard for a couple of Cornell scientists to cover the entire continent). If you have any ladybeetle observations be sure to send them in!

I just happened to spot this guy sitting still in amongst the leaf litter while I was photographing a fly, not a foot away. It is a true bug with the scientific name Menecles insertus, and was easy enough to pick out in the Kaufman Insect guide by its all-brown colouring and pale stripe down its back. It seems to be a fairly common insect of the east, feeding on a range of deciduous trees. My guess would be that its brown colouring is an adaptation to a late fall and early spring adult stage, since the predominant colour in the landscape at those times of year is the brown of dead leaves. There wasn’t much info available in either resource I checked, though, and I’m simply hypothesizing that it overwinters as an adult since that would make such an early spring appearance easier.

I found two of these spiders, in two different spots. I think they’re a type of wolf spider, but I don’t have a definitive ID on them yet, either. They were scuttling through the leaf litter, and, aside from the flies, were the main source of eye-catching movement that I encountered. All of the rest of the insects required examining the ground more closely.

I also don’t know what this beetle is. It was just a wee little thing, less than half a cm (less than 1/4″) long, but a bright iridescent bronze. I had happened to kneel down to inspect a large rock with mica deposits in it, and as I was checking out the mica, a little beetle comes wandering up over the top of the rock in front of me, like he wanted to make sure he was counted.

Edit: In the comments, Ted makes this suggestion: “The beetle is a leaf beetle (Chrysomelidae) in the genus Graphops (subfamily Eumolpinae). It could be G. curtipennis, a common eastern North American representative, although there are a number of species in the genus that are difficult to sight ID.”

One other species I saw but didn’t post here was a diurnal moth, a small little tan guy, whose identity also remains unknown to me. It’s amazing how much time one can spend trying to identify things if one really wants to.

Finally, species #13, was these grasshopper nymphs (above and below). I found the green one first, and was quite surprised to discover a grasshopper. I didn’t notice until I got home that it was a nymph and not an adult. Part of the presence of grasshoppers so early is explained by this. It turns out they’re both Northern Green-striped Grasshoppers, Chortophaga viridifasciata. The species has two colour morphs, with both sexes occurring in both colours, but with females predominantly green and males mostly brown. Eggs are laid and hatch in the summer and over the course of the fall the baby ‘hoppers go through a few moults. The winter arrives while they’re still nymphs, though they may be anywhere from half-grown to nearly adults. They overwinter as nymphs and emerge early in the spring to finish growing. They’re usually the first species of grasshopper to be encountered as adults in the spring because they’ve got such a huge head start on development over other species that overwinter as eggs.

Total counts to date this season: 12 species of moth, 12 species of other insect. At March 17th! And spring (the official first day) not even here yet, it’s still four days away. I just can’t get over that. It looks like we’ll have to endure a few chilly days as a cold front moves through later this week and into the weekend, but we’ll be back up to these temperatures again next week. I wonder if I should wait till the 21st to declare spring finally arrived?

Along came a spider

When I was down at TTPBRS on Thursday, it was a pretty quiet day. Not too many birds around, so I spent some time examining the walls of one of the buildings for bugs or other interesting things. One of the creatures I came across was this jumping spider. Jumping spiders are tiny, less than a centimetre long, and fairly stocky. This particular one is a Zebra Spider (Salticus scenicus), so called for the striping on its abdomen. It’s a species with a holarctic distribution, found nearly throughout the northern hemisphere. There are more than 5000 species in this family of spiders, which represents nearly 13% of all spider species, the largest taxonomic family of the arachnids.

Jumping spiders have excellent vision, aided by two giant eyes placed on the front of their head, which gives them strong binocular vision, but in a narrow field of view. They have eight eyes total; two others are also located on the front of the head, but the other four are on their back. These remaining six provide the spider’s peripheral vision. They are also amazing jumpers (hence the name of the group). They don’t have the large leg muscles of some jumping insects (such as grasshoppers). Instead, their spring power comes from a hydraulic-like system that uses their interior body fluid (insects and spiders have their “blood” loose in their body cavity, rather than contained in a vascular system) to rapidly extend their legs.

Some jumping spider species can grow quite large; one African species can reach 14 inches in length. These massive spiders have been recorded to jump as far as 7 feet in a single leap. In the larger spiders, where you can clearly see their eyes, you can watch which way they’re looking. This is because the retina of the spider’s eye sits loose at the centre of the back of the “eyeball”, and the spider moves it around, rather than moving the eye itslef, in order to see. This causes the visible colour of the eye to change, depending on where the retina is. When the eye is blackest, the spider is looking right at you.

All spiders are predators, there are no herbivorous spiders. Zebra spiders feed on other insects and spiders that are their own size or smaller. As I stood there and watched this individual, snapping photos, I noticed a small brown spider crawling up the wall towards the Zebra, apparently oblivious.

The Zebra honed in on it right away. It patiently waited for the brown spider to pass it, actually moving out of its way, to one side, to allow it to do so.

Then, once the brown spider’s back was turned, the Zebra lined itself up, gathered its legs under itself…

…and pounced!

The brown spider made it out alive by rapidly letting go of the wall and dropping down on a thread. A happy ending for the brown spider, not so happy for the Zebra.