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Monday, 18 Dec 2017

Millipedes

 

 Don't poison that millipede!

 

 Abstract: A brief summary of the millipedes of Roleystone, foreign and native, their habits and numbers. Hopefully with understanding and some accommodation, people will not use poisons.

Millipedes (family Diplopoda which means double feet in greek). The name millipede means ‘a thousand feet' in latin--which really means they have many, but not 1000. They are distinguished as segmented worm-like creatures usually black or brown. Now, since the invasion more than 5 years ago, the most common species is the ‘Portugese millipede', of Order Spirobolida (Ommatoiulus moreletii).

See the Department of Agriculture and Food DoAF Farm Note, No. 02, September 2003 (Reviewed October, 2006) by Marc Widmer.

Portugese1

Portugese2

Photos from Mark Harvey and the Department of Agriculture and Food (DoAF)

 

These millipedes (and native millipedes) appear following a moist period with rain. They eat almost anything, including garden vegies and seem to converge on any waste or rotting material, acting as general disposers. They emerge at dusk and, into the night, are attracted by light. They can get through, under and over barriers and are smashed in doors, fall from ceilings and make a nasty and smelly mess on the floor, when you step on one. It is a suicide mission-trying to find mates; they generally do not breed or inhabit homes.

All millipedes are distinguished by having four legs on each segment, with (perhaps) 100 legs total. Details of their life cycle are in the Farm Note.

They eat mostly decaying vegetation, fungi and bacteria; generally they are one of the great recyclers of nature and are cleaning up our waste. Around full moon time in a moist period after rain in Autumn or early Winter, they hunt for mates; in some orders the male has one of the forward leg sets on the seventh segment modified into reproductive organs, gonopods; on the females are cyphopods, which are relatively poorly described and mostly indistinguishable between species. Some orders also have the second set of legs on the seventh segment modified for protection, the anterior pair, the coleopods; the posterior pair, the phallopods perform the sperm transfer. These sexual organs are a major feature in identification to Order and Species. See the enwrapment shown in the figure, with two individuals forming a double spiral (lower left).

Later the female Portugese millipedes lay about 200 eggs in a chamber; pinhead size, yellowish-white. The eggs hatch and a legless grub appears; the grub develops about 3 segments with legs in about a month. It moults and adds a segment with legs about 8 times the first year and is about 1.5 cm long. After 10 or eleven stages and about 2 years have passed, they are ready to reproduce, and you see them chasing mates on your front steps, again. They are very fragile and soft when they have just shed their old cuticle, which they eat. Nonetheless, it seems that millipedes were the first creatures to live permanently on land, so they are not all that delicate and won't be deterred easily.

There are about 1000 species of millipedes worldwide with about that many in Australia; but the Portuguese millipede is a particular pest in Western Australia. In behaviour you will find they are strong; when disturbed they flail about like a fish on dry land, or, alternately coil up into a single spiral. They are difficult to pick up and hold in the hand, have a strong and persistent smell that is very aromatic and most people consider unpleasant. Importantly they are slightly tapered toward the tail. The ones everywhere in Roleystone are usually black though I have seen brown ones and some are even a light brown.

During a walk of 5 km in Roleystone in a wet period one might see a thousand or more Portuguese millipedes. The species do seem to be nearly exclusive, however. That is, if there are Portuguese millipedes, there will be few or no other species around. Later, or in another place, however, you may only see one of the other species. In the bush, you see almost none. I expect they are in the litter. But near gardens or lawns, verges with trees and some understory and food, there are many. They only are apparent on roads and footpaths, which are hard surfaces they must cross to find food and mates.

 

Portugese3

Photo by Pat Scott

 

One native millipede , also of Order Spirobolida (Dinocambala ingens, above) is in the SW of WA; it looks quite similar but larger and more tubular than the Portugese millipede. It can also appear in plague portions. It is no where near as active as the Portugese millipede, coils from both ends into a double spiral and (if you look closely) has alternate black and brown in the segments. It is nearly without a smell; I suppose it isn't quite so generous with ‘spraying' (for defense) as the Portugese one. If it does smell, it is a smell quite different but somehow like that of the Portuguese millipede. Small, young millipedes look very much like the Portuguese millipede, except for the more tubular shape, brown and black, except they exhibit relatively friendly behaviour. Large mature ones can be as long as 10 cm. When coiling, they roll from both ends and tend to form a double-coiled spiral. In Roleystone, in a rainy period, their numbers could be as many as 1/5 the number of Portuguese millipedes. So they are also a pest-but perhaps we should be a bit tolerant!

A separate unknown native species is similar to D. ingens, nearly circular in cross-section without tapering at the head or tail, but has a large length to diameter ratio with about half the diameter. Also, it usually has a ‘reddish' head and tail and a quite variable colour; segments are sometimes nearly white or clear, sometimes with black and brown, sometimes just black. They do have a tendency to spurt brown dye when irritated, a mild smell and may invade households in numbers comparable to the numbers of D. ingens. Pairs of them have been observed in embrace, one wrapped around another, possibly having sex.

Our bias is that native millipedes are part of the natural system and general cleanup, consuming mostly rotting waste; moulds, fungi and bacteria. They tend to restrict themselves to that, except at breeding times. If I see one in the road, especially a large one, I throw it off to the side in which it is headed. The Portuguese ones I purposely try to squash and hope that the ants and perhaps the magpies will get the taste for them. There is some evidence that ants, magpies and bandicoots eat them.

There is a giant African millipede a foot or so long which is a significant food for Meerkats. They live for about 7 years and may be kept as pets.

I don't believe in poisoning millipedes generally, though the Dept of Agriculture and Food article lists many pesticides. Moats and traps can work; you may even trap them or drown them in a dish with smooth vertical sides. There is even a locally invented, commercial device, a garden trap with a light (J. Watkins and J. Italiano, call 1300 308 087).

Physical barriers work with smooth vertical surfaces. The DoAF recommend a barrier of thin galvanised iron, perhaps a continuous strip with a sill of an inch or so around your house; this is particularly effective if turned outward and downward. Better to exclude them with better sealing of doors and windows as well as roof spaces. They are able to enter the smallest gap and all loose fittings are suspect. Tape your screens or windows; have at least brushes on the bottoms of your outside doors.

For most of us, however, this is too hard. Simply collect them in a capped bottle; squash or flush them down the toilet. This is generally annoying; messy, smelly and time consuming but effective for a few intense weeks. There doesn't seem to be any real problem with contact or the smell though some people may be allergic to them. The smell is quite pervasive.

We have no experience with the electrical tape method suggested by the DoAF. The ABC suggests using glycerine on a toothbrush to clean off the yellow stain from tiles. Also a drop of pennyroyal in a teaspoon of bay oil in warm water sprayed on surfaces as a deterrent-at least it smells nice!

These two species of millipedes are drawn to the moon and appear mostly at times of the full moon, or our lights. But one can not spend full time ‘getting millipedes' so I just step on them outside and flush the ones I find inside. If one is keen, have a look under any foodstuffs or bits of timber outside on a moist night. Sometimes there are 100s in one spot, in a sex scene or food piss up! Remember they do not enter your house for any purpose except to find a mate, and they die trying.

 

native1 native2

native3

Photos by Chris Horgan

native4

 

 

 

There are at least two other native species in Roleystone. One of order Polydesmida (Antichiropus variabilis, shown in the four pictures above) is rare in Roleystone but is found in the Darling Range and the South West of WA; it is soft and camel brown with legs slightly more to the side and curved downward, resembling a brown centipede. As with the other species, it has no paranota (horns or protuberances on the segments). In contrast to the other species (O. moreletii and D. Ingens), A. variabilis has only 20 segments and is blind.

Our information is that A.variabilis is totally unrelated to the small backyard millipede in Sydney, even though they may look superficially alike.

 

sydney_millipede

Small backyard millipede in Sydney

Photo from Wikipedia

 

 

In perhaps 10 years and many thousands of km of walks, I have seen only a few of this native millipede. Nonetheless on the winter through 20th May 2007, 9 were sighted; three on the morning of 20th May 2007 after some mild rain and a rather cold night; four of the nine were somewhat darker brown. Further, during each of winters of 2007 and 2008 about 80 were seen, mostly on Wymond Road. Also, in 2008 nearly half of the larger individuals had gonopods, a slot with surrounding modified legs, on the bottom of the 5th segment, counting the head. It is noteworthy that, as with A. ingens, A.variabilis seems to have a ‘sit up and look around' behaviour (see the picture of D. ingens) and is quite clever at finding a way out of a bag!

It now seems clear that perhaps half of the millipedes observed in 2007 and 2008 were probably another unknown native species. This millipede is generally small, only around 1 cm long with the same shape and colour as A. variabilis but with dashed white lines along either side.

This is to acknowledge Mark Harvey, Western Australian Museum for his pictures and reviewing this article.

 

© Roleybushcare 2017