How To Kill Cockroaches

Let me be up front about this, if you have a cockroach infestation in your home that has spread to more than one room, you need to call in the professionals. Regardless of which species of roach you have (there are several), you are unlikely to solve this problem alone. 

A little bit of background info first. There are thousands of species of cockroach yet only about 30 are considered as pests. The majority are woodland insects from tropical and sub-tropical climates. Of the species considered as pests, the 4 most common and widespread are the German cockroach (Blattella germanica), the Oriental cockroach (Blatta orientalis), the American Cockroach (Periplaneta americana) and the Brown-banded cockroach (Supella longipalpa); although this is subject to vary in some locations.

Oriental Cockroach

(Blatta orientalis)

Can cockroaches fly?

Some species can. The American Cockroach is a good flyer. The Brown-banded is also a frequent flyer and I’ve heard people claim the German Cockroach can fly, although I have never witnessed it. Cockroaches are more likely to fly in hotter climates. I currently live in Turkey and occasionally get Brown-banded roaches flying in through an opened window in summer.

All the pest species of cockroach are omnivorous, meaning they will eat anything (including each other)! They are known to be carriers of many pathogens (harmful microorganisms). They are social insects, congregating together by releasing pheromone attractors and are nocturnal.



One quick way to identify cockroaches from beetles is that all cockroaches have antennae at least the same length as the body, often longer.

After mating, the female cockroach develops an egg capsule, called an Ootheca, which will contain numerous eggs depending upon the species (30-40 for German cockroaches, approximately 16 for Orientals for example). When the eggs have fully developed, the female will deposit the ootheca in a suitably dark and warm place and the eggs will hatch shortly afterwards. It only takes a few mating females for the population to grow quickly in a matter of weeks.

Cockroach Egg Capsules

brown banded ootheca

Cockroach nymphs develop inside an egg capsule, called an Ootheca. The number of nymphs varies amongst cockroach species.

Nymphs Hatching


After a gestation period, the Ootheca splits and the nymphs emerge. The nymphs moult several times as they develop to adult.

A Female Roach Carrying an Ootheca

german cockroach carrying ootheca

German Cockroaches carry the Ootheca until it’s fully developed. Most other species deposit the ootheca in warm, dark places where it remains until hatching.

So why do I say to seek professional help when your viewing this page to learn how to kill cockroaches yourself? Well, if you have not seen cockroaches in your home before, you probably have a new, small infestation and you can have a go at that yourself, we’ll go onto that in a moment. But if you are seeing roaches in several rooms, maybe your kitchen and bathroom, it’s probable that you have a significant infestation already. That population is likely to have dozens of breeding females, if not hundreds, so there is a great risk of the infestation escalating further before you’ve had the time to learn how to eradicate them yourself. Another important factor is the type of premises you live in. If you live in an apartment, high-rise block or condominium, the service ducts, cable risers and other common areas may all be infested. If this is the case, the whole building needs to be treated at once, else you are just going to be constantly re-infested from your neighbors.

Let’s Get Down And Dirty!

So lets get back to the scenario where you’ve found one or two cockroaches in your home. Chances are that you will be dealing with one of the 4 most common species I mentioned earlier. If they are small (13-16mm), mid to light brown in colour, they will either be German or Brown-banded cockroaches, probably German (by the way, in Germany, they call them French cockroaches!). If they are dark brown, almost black and about 25 – 30mm, they will be Oriental cockroaches and if they are a mid-brown and a scary 25 – 38mm in length, they are probably Americans (why are things always bigger in America?). Being larger and slower to breed and develop, the latter two are not as big a problem as the first two. It is likely that they entered your home inside a box or packaging and squishing them on sight is all you will need to do to eradicate them. (By the way, the pooh from these 2 species are clearly visible as hexagonal pellets and are found in the vicinity of their daytime hiding place. If you see pooh, it’s likely that you have more than one or two cockroaches in your home). You can also purchase an aerosol spray for CRAWLING insects (not for flies) and apply this spray to areas where these insects tend to hide during the day. This would be anywhere warm and dark such as behind and beneath a cooker, underneath the hob plate on a stove, underneath baths, inside immersion heater cupboards, etc. Although they are capable of climbing, both the American and Oriental tend to be mostly active around floor level.

Because cockroaches will eat anything, it is really important to keep your home as clean as you possibly can. The less food available will help keep the cockroaches centred on fewer places, thus making them easier to locate and deal with.

Now let’s look at dealing with the one species you really don’t want to get in your home, the German cockroach (Brown-banded can be dealt with following the same methods). German cockroaches are expert climbers and being small, can take advantage of the tiniest gaps and cracks. They can walk up any surface, including glass. As with all cockroaches, they prefer warm, dark areas, preferably close to a food source.

German Cockroach (Blattella germanica)

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How To Get Rid Of Cockroaches With A PROVEN SYSTEM You Can Use That Works…

There are two different approaches to eradicating cockroaches. One is the use of Insect Growth Regulators (IGR’s). These are baits that contain a chemical that, when digested, prevents newly hatched cockroaches from reaching adulthood and more importantly, sexual maturity. Consequently, after the resident population has fed on the IGR, none of their offspring will mature and bread and so the reproductive cycle is broken and the population will expire naturally. This is a relatively long-term treatment and is used to eradicate large scale and difficult infestations. A more accessible form of treatment that is available to the homeowner is the traditional approach of insecticides.

Applying Insecticide

Of the insecticides, you can use water-based residual insecticide sprays, aerosols and gel bait stations. I recommend arming yourself with a good torch, your Sherlock Holmes Deerstalker and an aerosol spray. Be prepared to get down and dirty because these roaches will hide in the most inaccessible of places. We’ll use the kitchen in this example as it’s the most common room for cockroaches to inhabit, but the same principal can be applied to any other location. 

So what conditions do cockroaches prefer? Warm, dark, humid and a ready food source are what they will look for, so the biggest source of heat in the kitchen is likely to be around your cooker. Pull it out if you can and check all around the back and underneath. The cockroaches are unlikely to be sitting there waving at you. Pay attention to the very small gaps where any two bits of metal join. Use you torch to peer into these crevices. Quite often, the only thing you will see to give the roaches away is a pair of antennae poking out. Use the aerosol (fit the long plastic tube extension if it is supplied with one) to apply short bursts of spray into these crevices to flush out any hiding roaches. Although the aerosol spray will kill the roaches, its main purpose here is to help you identify where they are hiding.

Once you have located your unwanted lodgers you can choose to apply a water-based residual insecticide or some of the new fangled gel-bait stations that are appearing in the shops. Now it’s likely that your aerosol flushing spray and your favourite squishing finger will have killed the majority of the cockroaches present, so any further treatment should really just be mopping up a few stragglers. Which method you choose is probably going to be down to cost and availability. You will need to apply a residual insecticide to each of the gaps, cracks and crevices where the cockroaches are harbouring and, to be thorough, to all of these places throughout the room. If you choose to use the bait stations, attach these, by using the tear-off sticky patch on the base, to surfaces close to where the cockroaches are hiding.

Follow the instructions that are supplied with the bait stations to determine how many you will need to use. Keep in mind that with the bait stations, you are relying on any cockroaches finding the bait station and feeding from it. So make it as easy for the roaches as you can and don’t leave any alternative food source (like crumbs or the leftovers of last night’s curry) available to them.

Providing you have been thorough with your search and your application and your infestation was localised, this should be sufficient to solve your problem. Keep an eye open over the following days and re-apply your insecticides if you are still seeing roaches after a week or so.

What’s possible if you don’t take action.

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