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Life in the Woodpile

06 Nov

keywords: insects, firewood, woodpile, lichen, beetle

I want to put in a plug for bugguide.net – a great resource for bug lovers. Their community of experts was very helpful to me as I tried to ID some of these creatures.

Our woodpile got huddled up just before our first snow and has now begun to feed the stove.

The logs in the pile are little snippets of life that, for the most part, originally came together high above the ground.

Inspecting the bark and rooting underneath it can reveal life that is usually far from view. (It can also make wood stacking somewhat less efficient!)

Each type of tree and the various grades of decay form habitats for numerous plants and animals.

For example, focusing in on the center of the uppermost log reveals...

a tuft of green lichen formed by a species of Usnea or beard lichen.

Usnea are fine, thread lichens with a bungi-cord-like core. They are rather sensitive to air pollution and often roost high in the tree tops.

Zooming back out to snoop beneath the bark of the lower log, reveals a white web of fungus and ...

a swirl of little white worms which appear to be wood maggots. While I'm unsure exactly which fly deposited these, it seems that several species take advantage of moist, decaying wood to lay their eggs which then develop into predatory maggots that stalk the rot. There is certainly enough there for the eating...

These Collembola (or Springtails) seem to like grazing on the fungal plains that cover many decaying logs. The below video shows part of the 'herd' going about its business. Springtails are so-called because of the 'spring-loaded' hair that they usually possess. It is this that gives springtails such as snow fleas the ability to hop around. This species seems less jumpy although, at the end of the video, one does seem to make a surprising little leap.

Click here for video.

Fungi and algae team up to create some of the most beautiful 'paintings' on the log surfaces: the lichens, an example of which, the Usnea, we have already met. Lichens are a fungal framework inhabited by an algal, photosynthesizing core. The relationships are complex but often seem to be symbiotic. The algae provides the sun-powered sugars, and the fungus throws in structure and some powerful, rock-dissolving enzymes. At least four 'species' (actually pairings of fungus and alga species) of lichen are visible in this picture: an Orange-cored Shadow Lichen (most intricately dissected), a Green Shield Lichen (on the right), a Brown Shield Lichen (darkest green) and a Hammered Shield Lichen (the 'dented' one).

This close-up of an abrased Hammered Shield lichen sheet shows the bright green alga sandwiched between the fungus covers.

Some lichens, such as this Orange-cored Shadow Lichen contain a differently colored heart but, as the overall color suggests, still are home to green alga. A bit of the orange is showing in the broken tissue at the upper right.

As this picture illustrates, some lichens cling to the wood with pseudo roots and share space with the verdant mosses (a group of plants who contain their own chloroplasts and so don't rely on alga for their solar cells).

Also present are Liverworts like this Frullania species which resembles a string of tiny, green pancakes.

Some lichens are less 'up-standing'. The lichen in the lower right-hand half of this picture seems to be a crustose species, the purple dots are probably its spore-producing structures.

Meanwhile, back at the mushroom... other creatures besides Springtails are feeding amongst the fungus. This is a Minute Tree Fungus Beetle of some sort; they are minute - this one is not much bigger around than the wire of a paperclip. These too seem to wander about the fungal forest as shown in the below video. Reportedly, they too eat fungus, although there seem to be some fairly specialized relationships, and I can't tell you whether these beetles were wandering amongst potential food or 'mushroom hunting' for just the right fungal dinner.

Click here for video.

Another tiny member of the demolition crew (they're at work decomposing the deadwood) are the orabatid mites. These mites are often very common in soil but apparently also venture into the woodpile. This one is pictured beside the tip of a paperclip.

Moving in closer, reveals that the shiny 'BB' has protruding fenders, those bulges are movable shields that the mite can close to protect its tender legs from predators. These animals are very shiny, and the light circle on the back of this one is the reflection of my camera lights. The below video shows this tank-like mite in motion.

Click here for video.

A larger member of the decomposing crew is the Wood Louse - a species of 'Roly-Poly' or Pillbug who feeds upon fungus and other organic debris. Like the mite, it's heavily encased with armour.

The most familiar form of millipede is also encased by hard exoskeleton, one which often persists after death, as happened here. Death may however not come for several years - a fairly long life span for such a small creature.

This strange creature sporting a paint brush on its rear is also a Millipede (a Bristly Millipede, Penicillata to be precise). It lacks the hard exoskeleton but its hairs, like those of some caterpillars (not to mention porcupines), seem to deter predators. For a detailed, illustrated account of how these bristles thwart ants, see the below article. These animals also feed on fungi and the like.

Link to millipede article.

One other form of self-defence is to carry your castle with you. Caddisflies do so in the water, and 'Bag Worms', amongst others, do it on dry land. Bag Worms (Psychidae, which I am guessing this is; the other option would be a Casebearer) are actually moths. In many instances, the female, even when mature, is wingless and remains within her silk-and-debris shelter. The video below shows a bag worm making a risky traverse across some tree bark - another reason for its production of silk soon becomes evident!.

Click here for video.

The fungus don't always lose out to the animals. In this case a fly, perhaps the adult of those earlier maggots, appears to have been overwhelmed by a fungus.

As all these juicy decomposers suggest, predators are lurking. This is, by log-life standards, a huge beast known as Alobates pensylvanica or the False Mealworm Beetle; it was about as long as the last joint of my middle finger. Both the adult and its larva are active predators. Beetles have intricate mouth parts, the video below shows this beetle using some of its mouth pieces to 'taste its way' along a log.

Click here for video.

Just to show why not only the adult beetles but also their larvae are to be feared by the firewood's smaller life, this is the larva of a Scarab Beetle, such as a June Beetle or a close relative. Those powerful jaws are meant for grabbing. The below video shows the grub climbing up some wet paper towel; notice how it uses small hooks on its feet, its large jaws, and a humping motion of its stout body to propel itself along.

Click here for video.

While this larva (probably of a Fire-colored Beetle - Pyrochroidae) looks relatively meek at this scale, a close up ifs face...

shows that it too is a predator.

Tiny prey call for (or at least are eatable by) tiny predators. This appears to be a young crab spider of some sort and was originally scurrying about the logs.

A close up of the same beast reveals its two baby-blue tiers of eyes (8 eyes total). The open legs are held somewhat like the pincers of a crab (which incidentally are fellow arthropods, like the insects). Crab spiders do not use their web in hunting but rather chase or ambush prey directly.

A somewhat bigger spider is also prowling, this one - perhaps 2-3 times the size of the previous species - may be a Running Crab Spider (Philodromidae), yet another webless hunter. Actually, Crab spiders (running or standard model) do spin silk, but they do not make hunting webs. Instead, they use the silk as an enclosing cradle for their egg masses and as a safety line.

Apparently, not everyone hanging out beneath the bark is intent on eating fungus or eating fungus eaters. This weevil, kindly ID'd by V. Belov of bugguide, is apparently Mecinus pyraster, a feeder on Plantago (which, in turn, is a naturalized European weed). Needless to say, there is no Plantago growing beneath the tree bark, but perhaps this one was seeking a refuge for the winter. As its food source would suggest, this weevil is also a European import.

Speaking of imports, this appears to be Lepidocyrtus paradoxus, another flavor of Springtail (but, surprisingly enough, perhaps the same genus as those shown earlier); it is apparently also a European import. . For some reason I think 1960s Cadillac when I see this one. Despite looking like a somewhat juicy, if bouncy, morsel, at least some Springtails have poisonous blood which deters predators.

Leaving the world of the insects and slowly coming back to our own, this seed of Virgin's Bower was trapped on the bark of a log.

Such is a first installment of 'life on a log'. One of the thrills and frustrations of writing this was the realization of how much life could be found on and beneath the bark. Each log, it seemed, added yet another organism. Knowing when to stop was difficult, but plunging into this tiny world was magical.

The logs still end up in the heating stove, but I now put them in a bit more respectfully.

 
1 Comment

Posted by on November 6, 2011 in Nature

 

One response to “Life in the Woodpile

  1. Brian Lowery

    November 16, 2011 at 3:31 am

    Conrad…. THANK YOU VERY MUCH! It was kinda magical for me also to see the details of “Life in the Woodpile.” Your running commentary and wonderful photography is what really made it so.

     

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