What’s the best cockroach killer?

A common mistake that people make with any type of bug or insect is that to assume that the only way to kill it is by poisoning it.  In other words, it doesn’t occur to most people that there are many options other than fly sprays for killing cockroaches, flies, mosquitoes, or spiders.

And these options should be considered, because as anyone that has used a fly spray will know, with modern formulas (containing synthetic pyrethroids) the insects go through a hyperactivity period before they die.  This is because of the mechanism of the insecticide.  Essentially, they lose control of their muscles and this causes them to shake themselves to bits, internally.  This process can be very unpleasant as with a cockroach you see it scuttling uncontrollably all over the place.

There is, however, a better way.  Use an oven cleaner.  In particular, use Mr Muscle.

Image result for mr muscle oven cleaner

This product has a very rigid foam which drowns the cockroach and immobilise it while it essentially suffocates.  So you simply spray it on, the cockroach gets immobilised in the foam, and then you come back a a few hours later and wipe it up

How to Kill Wasps

This might not be as obvious as it seems.

It would be easy to treat wasps like flies, and simply spray them with a can of Mortein. The trouble with this approach, however, is that the active ingredient in Mortein, and every other insecticide on the market, is a pyrethroid.

Pyrethroids are wonderful insecticides, in that they are effective killers of insects, which have very low human toxicity, but when it comes to wasps, they have a drawback.

That drawback is that the insects go through a hyperactive stage before they die. In other words, they don’t just drop dead as soon as you spray them.
When it comes to nasty things like wasps, this can be a problem for obvious reasons. What you want is something that will disable the wasps as soon as they are sprayed.

Fortunately, this can be done. We sometimes make the mistake of thinking that poisoning is the only way to kill an insect. Now if we think about it for a moment, we can see in the world around us that there are many ways that insects, animals, and people die.

That is, aside from poisoning there is suffocation, blunt force trauma, knives and guns, drowning, heart attacks, and so on.

And so it is with insects. And in this case, the best instant killer for a wasp (or a cockroach) is an adhesive of some kind.

An example would be hairspray. Hairspray, of course, contains adhesives for sticking the strands of your head together, specifically, gums and resins.

These gums and resins are dissolved in an alcohol base, so what happens when the wasp or cockroach gets sprayed is that the solvent attacks any mucous membranes (in just the same way that pure alcohol up your nose or in your eyes will sting). This has an instant disabling effect. On top of that, the alcohol has a freezing effect as it dries, and when it does dry they find that every orifice is covered with a suffocating layer of gum or resin.

Pretty gruesome when you think about it.
But any adhesive will do. The wasps who built their nest on a water feature outside my house met their demise with a can of Kwik Grip spray. I just walked up, plastered their nest with it, and the result was both spectacular and instantaneous. Every single wasp disabled and killed immediately.

Of course, the use of any adhesive will leave sticky stuff behind whatever you spray it, but outside that it is not of course a problem

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.

Pea Beu Nature

One of the least successful products in the Pea Beu range is the odourless product:

Years ago this was called Pea Beu Nature, and the idea was that without a fragrance, it didn’t have a “chemical” smell, and was therefore more natural.

Unfortunately, it has consistently been a poor performer, as revealed in this review. The interesting thing about this, however, is that the level of insecticides in this product are exactly the same as the other products in the range.

in terms of why it is perceived as being a poor performer, a large part may be that when can’t smell anything, you assume that nothing is coming out. in other words, when people complain about the smell of a fly spray they think they are smelling the insecticide when in fact they aren’t – it’s the fragrance.

Anyhow, if you want to kill a spider with direct spray, there are plenty of other things you can use – like hairspray for example, as it gums up all their pores and suffocates them.

Alternatively, an excellent cheapy fly spray is IGA Fatal, as it appears to be solvent based, like the Mortein Fast Knockdown.

Exploding Roach Bombs

A house in Middle Swan was blown up by roach bombs yesterday.

What happened?  Are these things dangerous?

The short answer is “no” if they are used correctly.  They contain insecticide, water, and a hydrocarbon propellant.  The way they work is you click the valve at the top open, it locks in place, and they dispense the entire contents into the air.  The insecticide then settles on all hard surfaces, and kills any cockroaches in the vicinity for the next few months.

As it comes out of the can, it is not flammable as it contains water.  What happens then, however, is that they separate – the water (and insecticide) fall to the ground, whereas the air fills with the flammable hydrocarbon gas (normally propane or butane).

The only question then is how much is there in the air?  Normally, there is not enough in one can to reach a high enough concentration (the Lower Explosive Limit) to be explosive.  What happens, however, is people think that if one can will work, then five cans will work better.

What’s wrong with that? That makes sense doesn’t it? Well, five cans contain five times as much insecticide as one can, of course. Unfortunately, they also contains five times as much flammable gas. Frequently, this will put enough gas into the air to reach the lower explosive limit and the result is rather spectacular.

Consequently, there are many stories, particularly in restaurants, of places getting blown up because they used too many cans at once, and mythbusters quite elegantly showed what can happen.

So the lesson is, read the instructions on the can.  They will tell you what the area coverage of a single can is, and you don’t need to use any more than this.  In other words, one can at a time!

But if you do want to use more, do it over a few days – don’t let off too many cans at once, or you won’t have a house any more!

Incidentally, 25 years ago when people were less concerned about safety than they are today, fly sprays were a lot more flammable – the legendary Pea-Beu Tri Kill is a case in point!