20,000 Micrometers under the Debris

The weather has been cool and overcast and most insects have gone into hiding to sit it out. Since there was a paucity of animals to photograph in the woods and fields it looked like a good time to take a peek beneath some rocks, logs and leaf litter. There's an entire world we’re seldom aware of under the surface of the soil, with an ecology of its own that both provides the support for and receives nourishment from the living things above.

Cornfield Ants or Citronella Ants (Acanthomyops sp., a subgenus of Lasius) – due to their subterranean lifestyle these common ants are rarely encountered. This group is scurrying to move their larvae to a safer place.

Even though they seemed on the large side, in the field I still mistook the rounded yellowish objects seen in the next photo for eggs. When I zoomed in on the image on my computer, my wonder of modern technology revealed that these were not eggs, but root aphids.

Many species of ants are symbiotic with aphids, guarding and "farming" them for the honeydew the aphids produce. But – these are called "ant-obligate" root aphids. Obligate meaning what? ... do they totally rely on the ants to complete their life cycle? No one has answered this intriguing question at BugGuide.Net, and I can't find it elsewhere on the Internet.

A "wireworm", the larval stage of a Click Beetle ... I have no idea what species.

Another insect larva – the immature incarnation of a Fishfly (Chauliodes sp.). Having overwintered underwater, it has abandoned its aquatic abode and prepared a cozy place under a rock where it can pupate. The small red "bug" to the left of the Fishfly is a Velvet Mite (an arachnid, related to a spider), and to the right is a Sowbug (actually a crustacean, like a crayfish).

Although it's not an uncommon insect, only those of us who have nothing better to do with our lives than roll over rocks and rotten logs are apt to chance upon the Camel Cricket. This one is probably genus Ceuthophilus, and it is not only virtually blind, depending on its long antennae and legs to navigate its stygian environment, but is wingless and unable to chirp like many other cricket species. The lack of an ovipositor indicates it's a male.

A Wood Cockroach, probably Parcoblatta sp. – judging by their numbers these insects won't be making the endangered species list any time soon ...

One of the common small cylindrical millipedes, probably order Julida. Millipedes have two pairs of legs on each body segment, and in most groups the legs on the seventh ring are modified copulatory organs called gonopods, the shape of which is an aid in identifying species. However, I didn’t examine any of the millipedes in the field, nor did the camera capture enough detail for me to guess at assigning a family, let alone a genus or species name.

If they feel threatened millipedes will often curl up in a spiral defensive posture, presenting their tough exoskeletons to the outside world. Some species also exude fluids that would-be predators find noxious.

Based on the number and profile of the body rings, this millipede found creeping about in the woodland leaf litter belongs to the order Polydesmida. Beyond this, I can’t say whether the two differently colored millipedes belong to different species. For all I know, the pale millipede in the first two images is the same species but has just recently molted.

Lithobius forficatus, the ubiquitous Stone Centipede. Centipedes have one pair of legs per body segment – always an odd number of pairs. The modified first two appendages, called forcipules, bear venom and are a feature unique to centipedes.

A closeup view of the forcipules.

Less often seen is the Soil Centipede (Geophilus flavus). This species can move both backwards and forwards with equal facility. According to one of my field guides these blind centipedes can penetrate as deep as 40 to 70 cm into the soil in search of insect larvae and worms.

Moving on to a couple of representatives of the order Isopoda, terrestrial crustaceans distantly related to crabs, lobsters, and much closer cousins of the freshwater isopods I photographed last autumn. Isopods have seven pairs of similar legs ... "iso" → same, "pod" → foot ... as opposed to, for example, a crab, which has very specialized appendages.

The Sowbug, genus Porcellio, has a three lobed head and two segments on the flagellum, the end of the long antennae. (Also like other crustaceans, Isopods have two pairs of antennae.) This woodlouse cannot curl up in a ball when disturbed.

On the other hand, the European Sowbug (Oniscus asellus) is often called a Pillbug because it can roll up if it feels endangered. The body ends in a two pointed telson (the telson being terminal body segment), and the flagellum consists of three segments.

"Bugging out" when life gets too scary ...

A Look beneath the Surface

This past summer I've made an effort to focus on visiting an assortment of our local wetland habitats and photographing their denizens (with an emphasis on odonates). As my camera is ill suited to underwater photography the subject matter is heavily weighted in favour of what lives in the vicinity of, or on the surface of, the waterways, thereby overlooking all the fascinating living things which make the water itself their home.

A metal sieve works best for sifting through debris that has collected in still pools of water; nylon or fibre mesh insect nets tend to snag and tear on sticks and rocks. Since it's autumn and much of the aforementioned debris is fallen leaves, it's not surprising that on my first couple of tries I dredged up some very leaf and stick-like insects. All three insects are true bugs, members of the order Hemiptera, with the piercing/sucking mouth parts typical of this group, and can bite if handled carelessly. And all three species are predacious, with raptorial front legs. More good reasons to sift the detritus with a sieve rather than one's fingers.

Left: Water Scorpion (sometimes called a Water Stick) ... Ranatra sp.
Center: Water Scorpion ... Nepa sp.
Right: Giant Water Bug ... Belostoma sp.

A couple of the stick-like Water Scorpions (Ranatra sp.): removing these insects from the water to take pictures didn't cause them any harm or distress. All of these bugs are air breathers, have fully functional wings and can easily fly to a new pool if their current home dries up, or in order to colonize new habitats. And despite the appellation "scorpion" the filaments at the end of the abdomen are harmless, they serve as breathing tubes.

A much more foliform – meaning leaf-like – Water Scorpion (Nepa sp.) in its aquatic abode.

Ventral and dorsal views of Nepa sp. It's interesting to observe the differences in behavior between the two water scorpion species. Not long after they were out of the water the two Ranatra became very active and blew their cover as "sticks". But when removed from its watery element, this insect refused to budge or twitch and did its best to behave like a dead leaf.

Another dead leaf mimic: this species of Giant Water Bug (Belostoma sp.) is only about 25 mm long, much smaller than its cousin Lethocerus americanus, which can attain twice this length.

Whenever possible it's preferable to photograph animals in their natural element. However, in the case of aquatic subjects glare reflected from the surface of the water can present a problem. Furthermore, the survival of many water dwellers depends on their ability to swim – fast – and they generally refuse co-operate and pose to have their picture taken. Moving this Fishfly larva (Chauliodes sp.) to a dry place was no solution ... it just lay on the rock, looking very much like a slug.

A small plastic container with a bit of water in the bottom served to confine the insect. However, I still had to work around glare and reflections, and for my next trip I'm going to try to a vessel that's off-white in order to produce a more neutral, less contrasting background.

Judging by the jaws I would have thought that the larval form of Chauliodes is carnivorous, but it appears that they will also consume vegetable matter and detritus.

The container also proved handy for temporarily constraining these isopods. Quite common in the submerged litter, these little freshwater crustaceans belong to the same order as the more familiar sowbugs, pillbugs and woodlice they so closely resemble. The best I could do in terms of an I.D. is family Asellidae (nor do I have any idea what kind of a worm that is in the second photo – it looks like an earthworm).

Saving the best (or perhaps the weirdest) for last: at first I mistook this peculiar looking wad of gray slime for a ... well, a wad of gray slime. It's actually an insect larva called a Rat-tailed Maggot, and will go through some rather dramatic changes on its way to adulthood; here's an image of the adult: Eristalis sp. Truth is indeed often stranger than fiction ...