Killing Cockroaches: What Works and What Doesn’t

cockroach on wall

When it comes to the common household insect pests, ants, fleas, and roaches, they are all annoying and yet it is only the cockroach particularly the large flying ones (those are American cockroaches by the way, and they are actually relative rare as a cockroach pest species, with the most common being the much smaller and largely flightless German cockroach) that can provoke such a visceral reaction of fear and disgust. I posit that this is because they are so much larger than ants or fleas, we can see every detail of their alien insectoid bodies with our naked eye.

dead roachFortunately, we live in the 21st century and as such we have many different options when it comes to eliminating these household pests. While you can always swat them on sight, that won’t even make a dent in their numbers and ‘old housewife’ methods such as herbs, cucumbers, and lemons are probably as effective at repelling cockroaches as garlic is at repelling vampires; simply pure fiction. You should kill roaches using poison as that is the best way to get rid of cockroaches according to this expert guide: Chemicals and pesticides are by far the most effective ways of eliminating cockroaches, even more so than other pests because cockroaches eat their dead, which greatly enhances the effectiveness of poison in reducing roach populations. However, use of these chemicals and pesticides, while mostly safe (otherwise they wouldn’t even be sold in the first place) does come with its own risks. In this article we will be educating you on the various types of active ingredients in roach pesticides, how they work, and what precautions to take.


Originally developed to treat parasitical worm infections, avermectin works by disrupting transmission of electrical activity in invertebrate nerve and muscle cells, causing death by paralysis. The active ingredient you should look out for in the labels would be ‘abamectin’. While used for cockroach control, it is used more in ant bait traps. While it is highly toxic in acute form, its concentration in such baits is very low, typically under 0.05%. Because it is designed to target invertebrates, it is highly toxic to fish. Quite safe to handle as it is not readily absorbed through the skin.


boraxThe most common would be borax or boric acid. It is an acute stomach poison for insects that disrupts their metabolic system but is relatively non-toxic to humans. However, it is toxic to plants so avoid using boric acid sprays unless you like brown and wilted house plants.


A slow acting poison to insects that works by disrupting energy production in their cells. Its toxicity is quite low to humans or other mammals (however very high doses have been linked to development of small testes in males) and it is not readily absorbed through the skin. However it is highly toxic to fish and other aquatic life.


A poison that disrupts the central nervous system of insects. Also highly toxic to fish and other aquatic invertebrates as well as bees, so avoid using them in your garden where bees pollinate. Fipronil can even poison a cockroach’s feces, which roaches also eat (gross!) and make the poison even more effective. While it can be moderately toxic to mammals if ingested, it is not readily absorbed through the skin; further it will not cause any nervous system damage due to the significant differences between mammalian and insectoid nervous systems.


chrysanthemumA class of pesticide that is derived from the chrysanthemum flower (and you thought all it was good for was tea!). Don’t be fooled however, just because it is a natural doesn’t mean it isn’t highly toxic. This toxin affects the nervous system of insects is highly toxic to felines. As such, pyrethroids are often found in flea sprays made for dogs specifically. Nevertheless, if ingested or inhaled it can cause moderate toxicity in other mammals. Pyrehthroids are probably one of the most common and oldest form of insecticides. Also, some studies have shown that due to its prevalence, cockroaches, in particular the German cockroach, has begun to develop cross resistance to it.

Diatomaceous Earth

Might not even be considered a pesticide as it is completely non-toxic. These are actually silica particles made from the fossils of diatoms (prehistoric single-celled organisms) and they cut the waxy exoskeleton of insects and absorb their oils and lipids, resulting in death via dehydration. While effective in killing cockroaches after contact, as it is not a poison, it will not result in a multiplier effect from roaches devouring other dead roaches and hence is not as effective against cockroaches. Recommended for widespread outdoor use.