Insect Populations Decline by 25% Since the 90s

Decline in Insect Populations Since the 1990s

If you didn’t know, insects are one of the most numerous organisms on the planet. As of today, scientists say there are between 10 to 30 million species of insects. Out of that number, ants alone have 14,000 different species. The last three decades have seen significant decrease in insect populations. But in which dimensions? Let’s look at the actual areas of reduction. 

  • Decrease in actual population: The biggest research on global actual insects population shows a big drop of almost 28% in the last three decades. The research encompassed a combined 165 long-term surveys from over 1600 sites. It revealed a sharp drop in the insect actual numbers. 
  • Decrease in number of species: There has been a sharp drop in the number of species as well. Studies showed that some species of insects have become extinct over the last three decades. This can be attributed to several factors like use of powerful insecticides. 
  • Decrease in geographic concentration: The areas infested by insects have also reduced tremendously. Before, many geographical locations across the globe had insects, a tale that has changed over the period of time. Less areas have insects at the moment.

Causes of Population Decrease

The decrease in insect population can be attributed to the following factors:

  • Use of pesticides – Highly effective pesticides have played a huge role in the reduction of insects. Research shows that pesticides are responsible for over 58% of the overall drop. This shows how far the pesticide industry has come over time. The quality of products has also increased significantly. 
  • Agricultural practices – Agriculture has also had its role in insect control. Farmers use a number of chemicals on their farms, something that seems not to work well with insects. In the US, a research showed that over 567,000 species of insects were eliminated due to agricultural practices over the last three decades. In addition, agriculture has opened up natural habitats of insects, hence destroying them. 
  • Destruction of natural habitats – We can’t exist for long if our natural habitat was destroyed. This is what happened to insects in the past three decades, their natural habitat has been destroyed by different forces. Human activities like agricultural practices have had a role in the destruction of insect natural habitat. Other natural occurrences like bushfires have also led to the destruction. 
  • Climate change – Floods, drought and other climate related calamities have significantly reduced the number of insects. Over the last 30 years, the climate has changed drastically affecting the life cycle of insects. Some insects thrive only in certain climatic conditions, and a change in climate signified their end. All of these factors are natural, with human activities causing insignificant impact.

Insects Whose Populations are Decreasing

Some species of insects, who generally help in pollination for crops and keeping pest populations in check, are seeing rapid declines in population. The decrease can be attributed to the factors we discussed earlier in the article. The most affected insects are: 

  • Bees:These are the insects behind honey. They are among the most affected insects when it comes to reduced numbers. Their numbers have been reduced mainly due to climate changes. Bees survive on certain climatic conditions and over the years, it has changed tremendously, leading to extinction of a good number of them. The use of insecticides on unwanted bees has also reduced their numbers.
  • Butterflies: According to statistics, the number of butterflies has reduced by 12% over the last three decades. The factors behind this are mainly human activities. Agricultural practices and other natural calamities have destroyed the natural habitat of these insects, leading to elimination of a good number. 
  • Moths: These are polyphyletic groups of insects that consist of every member of the order Lepidoptera that are not butterflies. Moths make up the vast majority of that order. Study shows that out of the 160,000 species that existed a while ago, only 68% of that exists today. The decrease can be attributed to climate change and other human activities. 
  • Beetles: Perhaps, beetles are the most common type of insects. They can be confused with other types of insects, especially bugs. The population of beetles has tremendously reduced over the last thirty years. The reduction can be attributed to the use of highly effective insecticides on beetles. Climate change has also impacted their lifespan. 
  • Dragonflies: These are insects belonging to the order Odonata. Adult dragonflies have a signature large, multifaceted eyes, transparent wings, coloured patches and an elongated body. The population of dragonflies has reduced significantly. This is attributed to the use of insecticides and changes in climate. 
  • Damselflies: These are insects of the suborder Zygoptera and order Odonata. They are almost similar to dragonflies in physical appearance but have smaller and slimmer bodies. Their population has significantly reduced and that can be attributed to climate changes over the last three decades.

However, Certain Insects Might be Increasing in Population


How To Deal with Floating Fire Ants

As other insects reduce in population, flies are increasing. What could be the reasons behind it?

They are highly adaptable – Flies can survive in any condition, irrespective of the climate. The best way to eliminate them is through the use of effective insecticides


As many of us will agree, these are among the most irritating insects. Cockroaches are increasing in population because of the following reasons:

  • Developing resistance to pesticides.
  • Thriving on human trash and artificial settings. 

Insect Population Decline May Lead to Pest Infestation

The decline in insect population isn’t good news to us. This is because it might lead to pest infestation. Fast breeding pests will increase in number because of warmer conditions. Their predators breed more slowly, which means there will not be enough numbers to keep pest population in check. For instance, beetles feed on cockroaches, but beetle populations are declining, meaning cockroaches will increase in population. To prevent this from happening, we need better pest control practices.

Be vigilant when it comes to pest control. Learn more from Pest Guide.

Pest Control against Unchecked Insect Populations Still Important

It is very important to keep unchecked insect populations under control. You can do so through the following:

  • Continue to keep clean
  • Get rid of trash and unnecessary objects piling up
  • Maintain healthy gardens to make way for non-pest insects

Contact Pest Guide to Protect your Home from Infestation

At Pest Guide, we have extensive information and expert guides regarding pest control practices. You can use our online form to get quotes from pest control companies. 

Subscribe to Pest Guide for updates, new reviews, and new information! 


“Tough, adaptable, generalist species — like houseflies and cockroaches — seem to be able to live comfortably in a human-made environment and have evolved resistance to pesticides.” – BCC report


Do declining insect populations have anything to do with pest control?

Yes, pest control has played a significant role in pest reduction. Its use is responsible for around 58% of the total reduction.

Are pests like flies and cockroaches also declining in population?

No, actually, flies and cockroaches are increasing in population. The reason behind it is that their predators are reducing in population, reducing threats and hence an increase in population. 

Is the decline in insect population a good thing or a bad thing?

No, the decline in insect population may lead to pest infestation. This is because their predators breed more slowly, which means there will not be enough numbers to keep pest population in check.

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