Saturday, August 21, 2010

Spider Snapshots

Several species of jumping spiders (family Salticidae) are extant in our area. The spider in the following four images is a female Bold Jumper (Phidippus audax), about 15 to 20 mm long. The three white (less frequently red, or orange as in this specimen) spots on the abdomen and iridescent blue-green chelicerae are typical field marks. Juveniles often sport orange spots.

Bold Jumpers come by their name honestly as they have been known to leap at photographers who have approached too closely. This spider was obviously feeling threatened by my presence.

There isn't enough detail in the next two images to determine if this is Eris flava or Eris militaris. For anyone interested here's a link to more information at BugGuide.Net. (EDIT: one year later, and lot more research ... I now believe this jumper is more likely genus Pelegrina).

I'm not sure as to the identity of the less vividly marked jumping spider in the next two images.

No collection of jumping spider images would be complete without the including photos of the ubiquitous Zebra Jumper (Salticus scenicus).

Sparking up the color scheme a bit: a female Black and Yellow Garden Spider (Argiope aurantiae) that has nabbed a paper wasp.

The following image is out of focus because the spider is shaking its web, and by no small amount, the spider was displaced by about two inches. I've observed this reaction in other orb weavers if they are approached too closely for their comfort. Is the purpose of this to make the spider a more difficult target for a potential predator?

Six-spotted Fishing Spiders (Dolomedes triton) are common along the north shore of Stoco Lake. The female in the image below is about 20 mm long. In the complex tangled web of life even large predators are not invulnerable; a smaller immature spider of this species has been captured by the Blue Black Spider Wasp (Anoplius sp.) in Life's a Beach.

As a rule Fishing Spiders are found on the shoreline or floating water plants. This is the first time I've seen one was making a web in the vegetation a few feet off the ground. The spider assumed this posture whenever I brought the camera up close.

Many species of Hymenoptera are parasites of spiders, but when I turned over a stepping stone in the garden I chanced across a scene where the tables were turned and found a Wolf Spider (Lycosa sp.) with an unlucky ant in its grasp.

Gardens host a variety of spider species; the spiders are attracted to the insects nectaring on the flowers. A Ground Crab Spider, probably Xysticus sp., assumes its characteristic ambush pose on an iris leaf.

Fungal Fly Photos

Throughout the summer it's not uncommon to encounter flies infected with the Entomophthora muscae fungus. The parasite doesn't merely consume the body of its host indiscriminately, it grows into specific areas of its brain to control the insect's behaviour, and before its demise the fly will climb to the greatest elevation possible in order to maximize spore dispersal.

When I chanced across this Greenbottle Fly I had the good fortune to have access to a digital microscope, and took advantage of the opportunity to capture images in more detail than is possible with a digital camera. Some of the images were taken by Laurie Campbell.

Not pretty pictures, but nature doesn't care about our human sensibilities.

Views of the greenbottle fly's head ...

... the abdomen, and the thorax.

This is the greatest magnification possible to achieve with the instrument.

Friday, August 13, 2010

Bug eggs on Purple Loosestrife, and other random insect encounters

This clutch of unusual eggs and small insects (?) on a Purple Loosestrife leaf was found along the Eastern Ontario Trail. Inspection with a low power magnifying glass showed that the little red-and-black objects were indeed insects, true bug (Heteroptera) nymphs, and my first thought was that this might be a species introduced to control the unwelcome plants.

Not so. It seems the momma bug is likely a Spined Soldier Bug, or a related species, and used the leaf for convenience and not as a future food source for her offspring. Here's a link to further reading at BugGuide.Net, and searching for "spined soldier bug eggs" at Google Images will return more photos.

Always look twice ... a misplaced patch of brown on a Box Elder (a.k.a. Manitoba Maple) leaf turned out to be the eggs of a Boxelder Bug upon closer inspection. A big thank you to Laurie Campbell of Campbell's One Stop in Tweed for the use of her digital microscope which made it possible to capture the images in such detail. There are also some good photos of Box Elder Bugs ovipositing at Seabrooke Leckie's The Marvelous in Nature.

With a length of only about 5 mm and cryptically colored, this tiny treehopper, Acutalis brunnea, is easy to overlook.

Inconspicuous against the background of foliage, this female Texas Bush Katydid (Scudderia texensis) was found perching in the planters downtown. Here's a link to an instructive web page used to identify the insect (includes range maps) ... Genus Scudderia

Moving on to some flies: the next two images depict a Syrphid fly of the genus Sphaerophoria (length about 10 mm). The larvae are good friends to have in the garden as they prey on aphids. More information on these flies may be found at BugGuide.Net.

Syrphid flies, a.k.a. hover flies or flower flies, form a large family. Many are boldly striped in some variation of black and yellow, imitating bees or wasps. This is a Transverse Flower Fly (Eristalis transversa).

Parhelophilus sp., nectaring on flowers of wapato, is another member of the family Syrphidae. These photos were taken along the shore of Stoco Lake.

Tachinid flies are another interesting and diverse family. The fly with the extraordinary spines on its abdomen in the first group of four photos is Juriniopsis sp.

The tachinid fly in the next four images is Archytas sp. These flies can be wary and hard to photograph but for whatever reason (good taste, maybe?) this one was quite unafraid and landed on my hand.

Various species of soldier flies of the family Stratiomyidae. Or rather various genera ... even for experts many insects can be difficult to narrow down to the species level using only photos. This cool lime green fly is Odontomyia sp.

A more robust soldier fly, Stratiomys sp.

And this fly? I can't decide what name to assign to it ... there are images of both Stratiomys and Odontomyia that look similar.

According to BugGuide.Net there are four different species in the genus Sparnopolius, but only S. confusus occurs in the east. To compare notes have a look at the images of Systoechus from 2008. I've made a judgement as to species based on images, is it correct in one or both cases?

North shore of Stoco Lake ... a mature female Swamp Spreadwing (Lestes vigilax) consuming a male Eastern Forktail (Ischnura verticalis). The colors on older females become obscured and they will often develop some pruinosity on the terminal segments of the abdomen.

A mating pair of Swamp Spreadwings (Lestes vigilax).

Despite the abundance of Blue Dashers (Pachydiplax longipennis) my encounters with mating pairs of this species are few and far between. Male and female odonates can be very different in appearance and prior to owning field guides observing a mating pair was my only means of establishing that a given male and female are the same species.

Last but not least: I don't recall how long ago the images of this pale green Assassin Bug were taken, but I couldn't ID the insect in a reasonable time and the photos ended up being buried in my "unidentified" files. Thanks to the images submitted by Mike Mills, a contributor at BugGuide.Net, I was able to identify my mystery bug as Zelus luridus.