Millipedes and Coopex.

Reader Kath asks

Hi again! We get literally invaded by thousands of disgusting Portuguese Millipedes every year. The only thing I’ve tried that works is mixing powdered Coopex with water & spraying round the perimeter of the house-have tried drenching a square metre of concrete & shining a desk lamp on it overnight=BIG pile of dead millipedes in the morning. They are a huge problem in lots of semi-rural areas (not sure about metro) Any advice or anything better than Coopex? We have dogs, chooks, fish, ducks & a horse (& kids!) so a bit concerned how ‘safe’ Coopex is? Thanks heaps,

I have the same problem, although perhaps not as bad as Kath.

The solution that Kath suggests – Coopex – is a good one. This is simply a powdered form of a common insecticide – permethrin – that you make and use yourself. You’ll also find it in many house and garden insecticides, but the beauty of making it yourself is that you get much better value for money.

Permethrin is a synthetic pyrethroid, and is the safest class of insecticide available. In terms of its impact on humans or animals. You can get this information from its MSDS, which says that it has an LD50 for rats of about 1g/kg.

This means that a rat has to consume 1g of permethrin per kg of body weight to have a 50% chance of being lethal. This is a very high amount, and renders it essentially harmless. So when you’ve made it up as a solution and sprayed it around, there simply isn’t enough there to be a hazard to any animals or children.

So make it up according to the instructions, and splash it around with a watering can. In wet weather like this, that millipedes love, you’ll need to reapply it regularly.