Adventures in Spider Misidentification: Spitting Scytodes

Spitting Spider Scytodes cf thoracica (Latreille, 1802)

Finished sweeping yesterday's snow off the walkways, had my coffee, and now it's time to get back to work. Sunday should be, at least in part, a day of rest, even if a deadline is fast approaching. Chapters won't write themselves, of course, but this week looks like working at a computer would be preferable to being outside. Average weather in Edmonton is an oxymoron: Pacific Lows and Arctic Highs push back and forth showering us with extremes. This week looks to be a depressing and Vitamin D-free seesaw of snow, sleet, ice and sunless days. So how about a quick dissemble to a sunnier clime with an ancient photo of a Spitting Spider?

Looks like a week for the snow shovel and ice scrapper

I think this is the cosmopolitan Scytodes thoracica (Latreille, 1802) and, although she inhabited our closet in Brisbane, one might find a similar slowly stalking spitter in many closets in North America. The Spitting Spider spits silk from its chelicerae (fangs) to tie its victims down before eating them. At first this seems strange: silk should come from spinnerets at the other end of the body. But, like most things arthropods do, it is really the jointed limbs that are the key. The fangs are just the first pair of limbs modified for feeding: spinnerets are derived from couple of pairs of more posterior limbs. Arthropods are composed of a series of what were originally very similar segments, each with a pair of limbs and each with the genetic potential to produce silk (silk is, basically, an excretory product). Scytodes are unusual spiders only in that they have turned on the silk producing abilities of the segment bearing their fangs.

More than somewhat alien-looking and silk issues from either end

But in a sense, this is reverting to what most silky arachnids do. Pseudoscorpions and mites, for example, also produce produce silk from their mouthparts and some mites use silk to trap prey (Spinibdella, a genus of snout mites being one such). Pseudoscorpions use their silk to make nests in which to hide away, as do many mites.

Silken cells under bark and some exposed pseudoscorpions

Of course, the gardener's least favourite mites, spider mites, also spin silk, but from their second pair of limbs, the pedipalps. Unfortunately, spider mites feed on plants and not on each other, but use silk much like many arachnids - to make nests and even to disperse on the wind - a method analogous to ballooning in spiderlings.

Two-spotter Spider Mites resting, moulting, and laying eggs in their web 

Come to think of it, we tend to assume what is most common is normal. Spiders are our common experience of silk spinning in arachnids and arthropods in general, but they are the only ones I can think of that produce silk from limb remnants near the middle of their body (over time, the spinnerets have become less limb-like and moved rearward - see the 'living fossil' Mesothelae). Tarantulas were once rumoured to produce silk from their feet, but this hypothesis seems to have come from too much Spiderman and not enough experimental rigour. Even caterpillars produce silk from their mouthparts and the only insect that I know of that has silk producing legs (Embioptera) uses its front feet.

Sticky feet yes, but not silky

Well, enough bludging for a Sunday morning - but not all in vain. I discovered a lapse I'd make yesterday about where silk in sea spiders (Pycnogonida) comes from - and learned that spiders are stranger than I thought.

Red Pond Mites: An anodyne for a gray day

A Limnesia looks on as two pairs of Piona grapple with dinner

I suppose most gardeners have noticed red mites scurrying across sidewalks and some have stopped to ponder them. One genus, Balaustium, is common enough on manmade 'rocks' that it has earned the common name of Concrete Mite. Species of Balaustium and their relatives are also called 'red velvet mites', the terrestrial members of a very diverse group (almost 12,000 described species) of often large and colourful mites in the hyporder Parasitengonina. The 'red velvet' comes from the often reddish fur and the 'Parasit-' from the peculiar lifestyle that these mites share. The first stage out of the egg, the larva, is a parasite that attaches to a host, injects enzymes, and imbibes the resulting dissolved skin and oozing fluids.The other stages are predators of other small arthropods or their eggs.

Adult of an Australian  red velvet mite (Charletonia sp.) feasting on spider eggs while sibling spiderlings look on in horror

Parasitengone larvae usually parasitize arthropods (when they bite mammals, birds and lizards, we call them chiggers). If you've seen an insect, spider, daddy longlegs or scorpions with curious blood-coloured blebs dangling from them, then they were probably parasitengones, but not necessarily larval velvet mites.  If the insect has a stage that lives in water, then the larvae are probably one of the 6,300 described (or uncounted undescribed) species of Water Mites.

Male Lestes damselfly with a cluster of red water mite larvae (Arrenurus sp.). These will eventually 'hatch' into red water mites.

Water Mites are sometimes called 'the butterflies of the mite world', but one gets a lot soggier chasing them then the typical lepidopterist does in a sunny field full of flowers. Adult water mites live in water, usually ponds, springs, streams, or lakes (a few have taken to the ocean) and swim or crawl about looking for something to eat. If you want to catch them, it's best to dress up like a hybrid of a trout fisherman and a butterfly collector - hip-waders and a very fine net.

Adult Arrenurus with several ostracods that might be dinner

If one is willing to take to the water net-in-hand, then you would have a good chance of finding lots of water mites. Each has its own preferred habitat, but sweeping emergent vegetation along the shores of lakes, ponds, and streams is an easy way to start. Dump the contents of your sweeps into a large white tray, let the muck settle, and watch for colourful red or blue dots swimming or crawling around. An eyedropper is the perfect tool for collecting the mites and moving them to a small container of clear pond water for observation.

Two Limnochares gliding past a water plant

Working out what the mites are doing for a living can be a bit more challenging, but with luck some will start catching  the copepods, ostracods, or cladocerans that are swimming around in your sample. Others may not be so cooperative, because they have more specialized feeding behaviours. For example, the large sack-like Limnochares hunt the tube-dwelling larvae of chironomid midges by searching the floors of ponds and lakes for the silken retreats of the midge maggots. When one is located, the mite creeps along the tube towards the open end and positions itself over the mouth of the tube. When the maggot's head pops out to graze on algae or detritus, the mite shoots its mouthparts out and spears the head of the midge. The much larger midge may thrash and squirm, but the mite slowly digests its brain and then feasts on the rest of its body: nature red in mite and worm.

Limnochares about to have midge maggot for dinner

Why are water mites red? Well, not all are - some are multicoloured and others mostly blue. The red colouration probably came from a common ancestor of water mites and velvet mites. The carotenoid (as in carrots) pigments that produce the red colour can help protect mites from ultraviolet radiation - essentially acting as a sunscreen. But red is also highly visible to animals with colour vision and is often associated with being distasteful or poisonous. Apparently, many water mites do make fish want to gag and they quickly spit them out and learn to avoid them in the future. It seems likely that red velvet mites also have a nasty taste. Yoder et al. (2006) have shown that when poked, Concrete Mites release a haemolyph-like fluid from a structure behind their eyes and the fluid spreads through the setae (presumably by capillary action) to cover the body. This is somewhat similar to reflexive bleeding in ladybird beetles. When the mite fluid was painted on to mealworms, predatory ants gave up trying to eat them. That is probably a good take home message - don't eat red bugs.

Don't eat red mites or bugs

References:

Proctor H & Garga N. 2004. Red, distasteful water mites: did fish make them that way? Experimental & Applied Acarology 34: 127-147. DOI:10.1023/B:APPA.0000044444.81413.1a Yoder JA, Benoit JB, Rellinger EJ, Ark JT, Halloran MC & Gribbings KM. 2006. Structure and function of the urnulae in Balaustium sp (Parasitengona : Erythraeidae) featuring secretion of a defensive allomone and alarm pheromone. International Journal of Acarology 32: 3-12.

Adventures in spider Misidentification: Wine, weevils, and cobwebs

Intrepid Cobweb Spider makes meal of weevil

October was a dreary month in the Home Bug Garden: frosts and clouds and snow and sleet and rain. Freezing rain does make snow seem more benign, but not any easier to shovel. Not a good time for bugs, but frosty evenings are an appropriate cue for an enophile to switch from summer whites to winter reds. A glass or two of Australian shiraz or New Zealand pinot noirs are pretty fair lubricants for the task of sorting through last summer's pictures and seeing what new records may be lurking among the folders. Unfortunately, although supposedly in vino veritas, I'm not finding many Latin binomials jumping out at me yet.

Theridiidae vs Curculionidae - not the most inspired of identifications

I'm guessing that this small spider is a female Theridiidae, a Cobweb Spider, because legs I are very long and legs III rather short. The other likely alternative, Linyphiidae, should have thinner legs of more uniform length and lots of macro-setae, or at least that is my impression. The beetle is clearly a weevil, Curculionidae, and perhaps a member of the subfamily Entiminae, Broad-nosed Weevils, but other weevils also have short, broad snouts. Well, one good thing about wine. The more one drinks, the less important knowing a name becomes and the easier it becomes to simply enjoy the evening and remember sunnier times. 

Adventures in Spider Misidentification: Agelenopsis

Albertan Funnelweb Spider: Agelenopsis cf utahana (Chamberlin & Ivie, 1933) 

In Australia, a funnel-web spider is something to respect. Typically these are rather large spiders with large, forward-striking fangs that can deliver a good quantity of dangerous venom. Although the females tend to stick to their funnel webs, the males wander and often get into trouble. The most notorious of these, the Sydney Funnel-web Spider Atrax robustus O.P.Cambridge, 1877, exhibits all the characteristics you'd least like to find in a spider sharing your garden: they are large, aggressive, and their bite can kill you.

Alberta Funnel-wb aka Grass Spider: not very large, aggressive, or venomous

In Alberta we don't have any relatives of the Sydney Funnel-web, but we do have spiders in a very distantly related family, Agelenidae, that make funnel-webs and are called Funnel-web, Funnel-weaver, or Grass Spiders. If you have walked through a grassy field in the early morning and seen a funnel-like web covered in dew, then you have probably seen the home of an agelenid spider. Last week as my wife and I were sitting on our back porch enjoying an Indian Summer evening, we discovered we had our own resident funnel-weaver sitting right behind us. Mostly she lurked in her funnel within the door drain, but she'd quickly dash out for a picture when an insect was tossed on the web.

Striped carapace and body, long spinnerets, funnel web, and eye pattern = Agelenopsis

You can just see the long spinnerets sticking out behind the longitudinally striped body of the spider above and the funnel web (at the top of the post). Along with the eyes set in two down-curved rows, all of these characters indicate we have a species of Agelenopsis. We think this is Agelenopsis cf utahana (Chamberlin & Ivie, 1933) because it looks right and the Strickland Museum has numerous records for the species, and no other, from Alberta.

The eyes have it: two curved rows = Agelenopsis

I'm pretty sure this is an Agelenopsis, but I use cf - an abbreviation for the Latin word confer ('compare') - as a CYA on the species. Other species may occur here and the identity in this genus, as in many spiders, is best confirmed by examining the palps of the male. If you want to see some excellent photos of the male of A. utahana, and an amusing video of the kind of trouble a wandering spider can get into, visit Splendor Awaits. As you can see from Adrian's video, male funnel-web spiders in Alberta are nothing to be afraid of and probably would much rather not make our acquaintance.

Friday Bug: Broad heads, thin necks, and ant mimics

Reaching for the sky, getting it in the neck

I don't suppose anyone ever asked General Sherman his opinion on good bugs, but he may very well have said that the only good bug he saw was dead. Then again, may be not. Entomophobia isn't universal or even all that common in people who are both observant and enjoy being out-of-doors. Few, except perhaps eccentric entomologists, are entomophiliacs, but even fewer are completely misentomonic. For example, seemingly everyone loves butterflies, and even it they have reservations about butterflies in general ( (e.g. if their cabbage was just eaten by green worms), few would be rash enough to cast aspersions on a Monarch.

Alydus eurinus Say 1825 meets well-camouflaged Crab Spider

Thomas Say was one of those eccentric entomologists who may have loved insects. He described more than 1400 species of them and, as both a Quaker and a resident in the New Harmony utopian experiment, one might expect him to have held a benevolent attitude even toward bugs. In any case, we can thank Thomas Say for today's unfortunate bug meal for a near perfectly camouflaged crab spider (probably a species of Xysticus): Alydus eurinus Say 1825, a member of the Alydidae or Broad-headed Bugs.

Ant-mimicing nymph of Broad-headed Bug (Alydidae)

We have three species of Broad-headed Bugs inhabiting our pasture. The late Alydus eurinus, its congener Alydus conspersus Montandon, 1893, and its more colourful relative Megalotomus quinquespinosus (Say, 1825) all belong to the subfamily Alydinae and so are probably feeding on the vetch, clover, and alfalfa. In any case, they are common and as nymphs (or larvae if you prefer) do their best to look like black ants.

Mystery alydid mimic of black ant

Unfortunately, I can only key them as adults, so the nymphs remain mysterious, but rather good mimics of ants (presumably the common Formica podzolica and its relatives). 

Megalotomus quinquespinosus (Say, 1825)

The "Broad-headed" aspect of these bugs is more or less visible in the picture above - the head is rather broad compared to the thorax, at least compared to most of their relatives in the Coreoidea. But I do think this 'common name' (possibly made-up by an entomologist) leaves something to be desired. It's nowhere as evocative as, for example, the Tarnished Plant Bug, which also seems to make a habit of getting bitten in the neck by crab spiders.

A Tarnished Plant Bug gets it in the neck from another Xysticus.

Adventures in Spider Misidentification: Six-spotted Fishing Spider

Six-spotted Fishing spider on Wild Rose

I'm pretty sure (that is I think) this is a juvenile Six-spotted Fishing Spider Dolomedes triton (Walckenaer, 1837). The white stripes along the carapace and abdomen and the striped femora are clues, and although it isn't fishing, it is perched near a lake and marsh. And then the abdomen does have a half-dozen pairs of white spots running down it. Unfortunately, the common name refers not to the easily seen abdominal spots, but to 6 large black spots on the sternum - something difficult to see unless the spider rolls over.

Six pairs of fuzzy spots yes, but not the definitive spots 

Charles Walckenaer was more whimsical, but no less obscure, when he named this species triton. The Greek god Triton is associated with the ocean, waves, and loud blasts of a conch shell as in "Or hear old Triton blow his wreathèd horn" (Wordsworth 1807). In the scientific realm, species of Charonia conch are called tritons, which does make sense since these snails do live in the oceans and their shells are used as trumpets. Also a moon of the planet Neptune (Latin for Poseidon, Triton's dad) is logically called Triton. But our spider inhabits the edges of marshes, lakes, and ponds. Perhaps, like Wordsworth, Walckenaer was yearning for simpler times, when naming our putative spider, or linking their hairy visage and aquatic lifestyle with the mermaid-like Tritons and ignoring the inconvenient seas. I think I like the last best and will absorb it into my "identification" of this week's lovely, hairy denizen of the water's edge.

Wild Rose with Tricoloured Bumble Bee

I'm pretty sure (that is I would stake a bottle of wine on it) that the fishing spider is sitting on a wild rose, but which wild rose I can't say. This is a bit embarrassing, since a wild rose is the Provincial Flower of Alberta, our licence plates proclaim Alberta 'Wild Rose Country', and even a political party has taken on its name. Although 'Wild Rose' is used loosely and rarely with specific identification, technically only one of the three species of wild rose in Alberta is THE Wild Rose: Rosa acicularis Lindley the Prickly Wild Rose. Since all three of these wild rose grow in the area and this isn't a post on 'Adventures in Plant Misidentification', I will remain mute on which species.

The Colour of Nightmares: Goldenrod Triptych

An unhinged triptych of trophic interactions

Goldenrod (Solidago spp.) in bloom, a cornucopia for the Home Bug Garden arthropods, always makes me feel a little sad but less sodden: the floods and hail of summer will soon be sliding into the green tomatoes and frosts of September. Still, it is cheering to see a dozen or more different species feeding on and at the goldenrod on a sunny summer afternoon. Pollen and nectar are the major attractions, but the Goldenrod Crab Spider Misumena vatia (Clerck, 1757) is there to feast on visitors like the unfortunate Striped Hairstreak Satyrium liparops (Le Conte, 1833) above.

Striped Hairstreak in happier times looking a bit brown

I suppose, technically, the Striped Hairstreak is a pest - its larvae will feed on cherry leaves, buds, and young fruit. But it is never very common and a few cherries are a small price to pay for such a pretty little butterfly.

Same hairstreak looking more lilac

This hairstreak seems to vary in colour from moment to moment from rather brownish underneath to a more purplish hue, depending on how the light is reflected from the scales on its wings. But its nemesis is the real colour artist, changing its pigment chemistry when it chooses a yellow flower as a lair.

Goldenrod Crab Spider in its natural hue

The yellow colour change of the Goldenrod Crab Spider takes several days to accomplish, so it probably started on a nearby Heliopsis helianthoides that began blooming a week ago.

Male Goldenrod Crab Spider

Males of the crab spider are smaller, darker, and don't seem to indulge in colour change. Possibly this is because a peripatetic lifestyle, wandering from flower to flower in search of females, precludes spending much time on any one flower.

Phalangium opilio Linnaeus, 1758

The third member of our unhinged triptych is a well-travelled harvestman. Although some people seem to find these daddy-long-legs creepy, they are harmless to butterflies and to people. They feed on small insects, pollen, and dead things. I suppose the one at the top may be dreaming of cold butterfly corpse for dinner, a fitting end to our food web.

References:

Defrize J, Théry M, Casas J. 2010. Background colour matching by a crab spider in the field: a community sensory ecology perspective. Journal of Experimental Biology 213: 1425-1435.

Defrize J, Lazzari CR, Warrant E, Casas J. 2011. Spectral sensitivity of a colourchanging spider. Journal of Insect Physiology 57: 508-513.

Insausti TC, Defrize J, Lazzari CR Casas J. 2012. Visual fields and eye morphology support color vision in a color-changing crab-spider. Arthropod Structure & Development 41: 155-163.

Riou M, Christidès J-P. 2010. Cryptic Color Change in a Crab Spider (Misumena vatia): Identification and Quantification of Precursors and Ommochrome Pigments by HPLC. Journal of Chemical Ecology 36:412–423.

Of Sloughs and Sogginess

Weather 1, Home Bug Garden 0

If you've read this blog for any length of time, you may have noticed that I tend to complain about the weather. Well, the weather, House Sparrows, and noisy neighbours, in about that order. Last night we had really noisy weather and neighbours: first the thunder, lightning, and deluge (3rd of the last week) and then car alarms blaring from 3 am until I dragged myself up to go to work at 5. When I realized I would need hip waders to get to the train, and that the cars bobbing around in the street were the source of the unending alarms, I stopped feeling angry at the neighbours and went and looked at my basement.

What does a 6-legged basement spider do in a flood?

What I saw was water and a sad spider, missing half its legs on one side, clinging to the basement wall above the wet. Not being able to claim I was missing a quarter of my limbs, it was time to start bailing and mopping. After Mrs HBG explained to the TV crew that we live in what used to be a slough, she put on her gum boots and slogged off in search of a train. I bailed and mopped and moped and then curled up on the dry spot on the bed (did I mention that the cat peed on the bed last night?) and dreamt I was in Queensland (where much worse floods occurred last year).

A pair of Perplexing Half-Black Bumble Bees ignoring the rain

And when I awoke, if not refreshed, at least dry, rather than continue to mope, I learned two new bugs from before the deluge. The first, Bombus perplexus, is a tentatively welcome addition to the Home Bug Garden. They do have a bit of a reputation for being aggressive, but so far they haven't bothered me. Unfortunately, they are very similar to the Half-black Bumble Bee Bombus vagans, so a bit of an id challenge.

Red Turnip Beetle Entomoscelis americana

The second is very colourful, but a pest, but not the pest I feared: the Lily Beetle. The HBG sports a number of lilies including a native, but mostly aliens raised from seed, donated by friends, or on found sale at a nursery. I never thought I'd become a lily lover, but they do have their charm.

Lily raised from seed awaits the deluge

Instead of a Lily Beetle, the HBG sported a Red Turnip Beetle. These eat crucifers such as cabbage and canola, and given how yellow with canola the countryside is at the moment, it is surprising that we haven't encountered them before. I suppose I will need to keep watch over my kohlrabi, but I know the worms of the Cabbage White will get them first, so why worry.

Bad, bad broccoli worm

Adventures in Spider Misidentification: Long jaws & horizontal webs

Neither jaws nor web to help, just Gestalt

The image above has appeared before at the Home Bug Garden, but never in a starring role (and once with the name misspelled). I like to think of this as a species of Tetragnatha - a Long-jawed Orb Weaver - and since neither the critical morphological character (the long 'jaws') nor a useful behaviour character (webs horizontal to the ground) are visible, it seems a perfect introduction to another Adventure in Spider Misidentification. Might as well jump in at the deep end: I'm guessing this is Tetragnatha laboriosa Hentz, 1850, the Silver Long-jawed Orb Weaver.

Horizontal web, often near or above water

I'm not being entirely arbitrary in my identification. Species of Tetragnatha are elongate and I have seen long 'jaws' on close inspection of other specimens. Also, the webs are definitely horizontal and often around the pond - sometimes strung from sedges over the water. Tetragnatha laboriosa occurs in Canada and the images at BugGuide look more or less the same. Isn't that enough?

Whatever this spider may be, there is one less aphid in the HBG

Well, no. A composite of characters from a variety of individuals is no way to come up with a reliable identification.  Best is a specimen, microscope, and key. Second best a really good set of pictures showing all the characters needed. I don't have any of those and I'm relying on something I learned long ago, in another land: the Gestalt of a Tetragnatha. That and an 'educated' guess on what species this might be. But BugGuide doesn't have pictures of all the species of Tetragnatha that occur in Canada, more than half of what they do have are unidentified images, and ominously one of these sets is labelled Alberta and Saskatchewan.

Tetragnatha maybe, species unknown

Well there's nothing wrong in being wrong, just in refusing to admit it. So, I'm pretty sure this spider belongs to Tetragnathidae and probably to Tetragnatha, but I think I'm going to have to collect a few and do some hard work at the microscope if I want to get any further.

Adventures in Spider Misidentification: Crying Wolf

Lycosidae or another booboo

Just a week ago it looked like it might be an early spring, but now all is grey and white and brown again. So, I'm continuing this weekend's nostalgic reminiscences of previous seasons' more lively times and I present a small female spider carrying her egg sack behind her across a carpet of green.

Female Wolf Spider with egg sac

 We think this is a Wolf Spider (Lycosidae) mostly because the egg sac is stuck to the spinnerets, but also she has a pair of large front eyes and the general on the ground brown spider with long legs look. I'm not sure that any of these characters are definitive, but the picture was taken with a point-and-shoot camera, so what you see is all you are going to get.

Male Wolf Spider wannabe with aphid

As far as I know, parental care in Wolf Spiders is limited to the females, so this male with its swollen palps lacks the useful egg sac character. Still, this looks wolf spidery to me and the male was hunting in the same area six weeks before the female was found carrying an egg sac. So there could be a cause-and-effect relationship going on here.

Big median eyes, swollen palps, and blurry aphid dinner

A higher quality camera captured this image, so we can at least claim that he seems to have the proper three rows with a large pair of eyes arrangement of a lycosid spider.

Concrete-coloured mystery spider

Lest you think we call all long-legged cursorial spiders Wolf Spiders, I offer this weak defence. We don't know what it is, but it blends into the sidewalk nicely. A few months ago I might have called out 'wolf spider', but now I've learned to look a spider right in the eyes before calling it a name.

Neither lycosid nor Betty Davis eyes for that matter