Scutigerella immaculata, aka Garden Centipede
"Bastards. Little white bastards."
— almost any organic farmer
The "Encyclopædia" Bit
Symphylans are lumped in to the Myriapoda along with the regular centipede and millipede familiar to many readers. There are some 120 species, which resemble pale centipedes ranging in size from about one-tenth to a quarter inch (2 to 10mm) long. They feed on organic matter in the soil and the rootlets of plants, especially seedlings. They can move quickly both laterally and vertically and as they operate best in warmer soils, tend to migrate downward up to two feet (50cm) in the winter, where they can still moult and breed.
They begin life with six pairs of legs, but add another pair with each moult, up to twelve. They are blind (lacking eyes) and share some features with early insects, such as fused maxillæ (jaws), certain features of their legs, and similar head construction. They sense and navigate using their long antennæ and can live up to four years.
A View From The Gardener
They are pernicious little bastards. They scurry through the soil munching down on root hairs, especially of tender young seedlings, devouring everything in their path. They seem hell-bent on devastating crops, and are practically indestructible. They have no natural predators, shrug off most insecticides and thumb their noses at control methods. In short, they're the mortal enemy of any vegetable grower, especially if "organic" methods are employed. There are probably a few in every garden, but rapidly become a pest if large amounts of organic matter are undisturbed for a while, when they can breed like bloody rabbits and take over.
I recall there being a few in my old veggie garden, but too few to take over the plot. Perhaps the cooler weather slowed down their development and reproduction. I was lucky.
My best friend is an organic farmer, and his relationship with them began over a decade ago when he took delivery of a load of compost that was infested with them. Unfortunately he did not realise this until the compost had been spread, and now they are all over his roughly thirty acres (about 12 hectares, whatever they are). They show up clearly as the crops are growing as large patches of thin and stunted veggies, looking as though the Four Horsemen of the Apocalypse and their steeds have piddled across the rows.
Some crops fare better than others; presumably for all their wickedness, symphylans have taste preferences (or perhaps are put off by certain chemicals in some plants). Potatoes are fine if they're planted whole, but cut them up and lo! there will be a squillion of them all over the cut sides. Chicories are also resistant to a degree, but beets and carrots beware! We've lost whole plantings to the white demons of the dirt.
The cut potato is actually a part of the standard test for symphylan infestation. Leave a cut potato (cut side down) on the soil for a day, then go back and count the wrigglers. Apparently there's a formula for how bad the scourge is. It ranges from "mild" which means you worry, to "severe" which means you start drinking heavily. We actually had a researcher who came out from a local university to do this test. He started drinking heavily.
This is a tough one. Even using modern control chemicals there is little respite, largely because the little buggers can retreat deep into the soil, possibly close to Hell where they doubtless originated. There are some soil fungi which exude an enzyme that can attack their chitinous exoskeletons, and minutely crushed shrimp shell can damage their integument. Ploughing or spading the soil damages them, but for farmers practicing "no-till" cultivation techniques these methods are not available.
Many many methods have been tried, some of which have apparently had years of research thrown at them, some of which appear to be more arcane ritual than science. Watering in large quantities of rosemary oil and other herbals was one of these. We've even joked about sacrificing to the Old Gods because none of the available "solutions" seem terribly effective; the only sure method is booze, which is like prescribing hot toddies for the common cold; it exists only to make the patient feel better.
Many conversations with J— over many beers