Last week we delved into the world of pesticides and discovered that they are categorised depending on which type of pest they are targeting.This week we are looking into insecticides, which as the name suggests, target insects. 

What are insecticides?

When we hear the word insecticide we no doubt immediately think of those used in agriculture but the fact is that they are common in households too. We probably haven’t considered it as an insecticide, but fly spray is one type and like those used in the produce industry, it is still essentially a poison. To fully understand how insecticides work, we are going to investigate: how they poison an insect; the damage they can potentially do to those who are exposed to them; whether we need to actually use them; and what natural alternatives may be available to us.

How do they work?

Insecticides can enter into an insect’s body in one of three ways: through the skin (known as the cuticle on an insect); through their mouth; or, through their respiratory system, (insects breathe through things called spiracles on the sides of their abdomen). The insect is poisoned: if the insecticide is left out for them to walk on and absorb via their skin; by eating the poison left out for them; or if they breathe in a spray through their spiracles.

Using insecticides is not as simple as releasing the poison for insects to take. To be used effectively, the insecticide needs to be used at a certain time of an insect’s development. Spraying after adults have just laid their eggs is pointless as usually adult insects die at this stage anyway. This is especially important when farmers are spraying poison, as you would not want to waste insecticide or use it unnecessarily.

Unfortunately, even when they are sprayed at the correct time, if some of those sprayed insects do survive and manage to breed then their young will have a resistance to that insecticide in the future. This makes us wonder how many of the targeted pests are actually eliminated through this process.

What are the effects on humans, other animals and the environment?

Insecticides, as with other pesticides, can be dangerous to all people but especially those in vulnerable stages of life, such as: the elderly, babies, young children, unborn children, pregnant and nursing women. Two studies linked insecticides in the home and garden to a greater chance of leukemia and lymphoma in children, and to behavioural difficulties in the children of women who had been exposed when pregnant. 

People are not the only ones who can be affected by insecticides. The problem with broad-spectrum insecticides is that they not only kill the problematic insects but can kill beneficial insects too like bees, butterflies, caterpillars. In light of the current situation where bee populations are scarily low, these sorts of side effects of pesticide use should be taken very seriously.

Labels on insecticides, and indeed on our government websites, also warn to: clear an area before using an insecticide; ensure food is away; cover fish tanks; remove pets and so forth. If used outside they stress to not spray insecticides on windy days and not to water your garden after using them as the poison can spread through the air, affecting the pollen in the flowers,  and be carried deep into the soil. It is obvious that these need to be used sparingly and carefully, which begs the question, are they worth it?

Do we need insecticides?

It was interesting to discover that most plants can naturally withstand a certain amount of insects attacking them and sometimes the plant and its fruit might provide better nutrients after the pressure of insect damage. This goes well with that old adage, what doesn’t kill you makes you stronger! It seems to make sense that fruit and veg in nature would not be affected by insects that much. If the natural food chain is working correctly, then surely this would not be a problem?

What are the alternatives?

There is no doubt that the safest way to use insecticide is to not use them at all. These days it is very easy to search up natural ways to deter insects. The Better Health website, run by the Victorian Government, provides a variety of ways for people to prevent insects from entering your home, or to catch them in a way that is not toxic. Some of the suggestions include: using particular plants to deter them; ensuring waste is properly contained; change bird bath water so it doesn’t attract mosquitoes; using a homemade spray made of natural ingredients.  Most of these won’t kill the insects but will stop them from arriving in the first place. It seems the right way to do things, doesn’t it?

When we consider the damage insecticides can have on our health, animals and our environment, it’s a comfort to know that our organic fruit and vegetables are free from these toxins. The fact that choosing to say no to insecticides benefits our world in so many other ways, is also a relief.


Australian Government Department of Health (11/10) 7 types of pesticides and how they enter animals and plants. Retrieved from:

Graham, S. for Networx (2/7/2009) Non Toxic Insecticide Alternatives.

Han, E. for The Sydney Morning Herald. (2/3/2017) Pyrethroid insecticides linked to abnormal behaviour in children, study shows. Retrieved from

Johnson, J. for Habitat Network (10/1/2017). Effective and Safe Alternatives to Insecticides. Retrieved from

Storrs, C. for CNN (14/7/2015). Report: Pesticide exposure linked to childhood cancer and lower IQ. Retrieved from

The Department of Health and Human Services, State Government of Australia (2018), Pest Control in the Home. Retrieved from

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