Wood louse photographed by Ron Neumeyer

Image of the month
Ron Neumeyer 1997

This is a picture of the ventral surface (underside) of a sow bug. It was taken with a Zeiss West stereo microscope at a magnification of about 5x, more or less as it would appear under a hand lens. I used a Canon T90 and dedicated ring flash. The flash is fastened to a bayonet clamping ring which allows it to be secured around the objective barrel. As the picture illustrates, this type of lighting produces a somewhat "flat" image, largely devoid of shadows. The film used for the picture was Kodak Gold 100. The image was digitized through transfer to a photoCD by a local retailer (not professional quality, but quite good, and much cheaper).

The scientific name for the sow bug, which grows to a length of around 20 millimetres, is Oniscus asellus. It is widely distributed in Europe, and has also been introduced to North America (where I live). The dorsal surface (topside) of the oval, grey body, which is rather flattened and arched, is covered with broad, armour plates, the lower margins of which can be seen in this photograph. One way the sow bug can be differentiated from its close relative the "pill bug", is by two prominent tail-like appendages that stand out clearly in this image. (Also, sow bugs do not roll up into tight balls when disturbed, a common trait of the pill bug.) The lower portions of the two elbowed antennae are visible at the anterior (head) end of the bug. These appendages extend about one-half the length of the body.

These so called land isopods produce from 20 to 200 young in early spring, and the female carries them around for three weeks in her brood pouch. They are found in moist areas such as under boards, paper, wood and other backyard refuse, where they feed on decaying organic matter.

Ron Neumeyer, 11135 Kendale Way,
North Delta, BC - CANADA
V4C 3P7 (604-582-2552)

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