What is causing these huge populations of insects around my yard?

ASK THE HORT AGENT

Question What is causing these huge populations of insects around my yard?

Answer Insect populations are affected by many factors. Some of these include genetics, food supply, weather, natural enemies and cultural practices. Most insects die before they reach maturity due to controlling factors in the ecosystem. This is important since insects have an extremely high capacity to reproduce within a short period of time.

Environmental conditions (weather) have a large impact on insect populations because they affect bugs directly and indirectly. For example, insects are directly affected by temperature. However, their food supply (plants) may also be affected by temperature and/or rainfall. Extreme environmental conditions can suppress or encourage insect populations.

The Sahel Desert Locust is one of the most feared locusts in the world. An outbreak in 1988-9 spread throughout Northern Africa, the Middle East and Asia, eventually impacting one fifth of the land mass of the Earth. Exceptional desert rainfall brings exceptional harvests and swarms of desert locusts.

Alarmists are now saying global warming could trigger insect population booms. In response, I think we will have fatter bats, lizards, frogs, birds and various other animals. The solution may be air pollution. Air pollution kills some economically important insects like honey bees and silkworms, but it also kills most insects in general (except cockroaches). Ecologists say an increase in pollution will cause a decrease in insects and therefore a decrease in bats, lizards, frogs, birds and the rest of the bug eaters. Hmmm. I wonder which situation will actually happen. Will we be warmer and overrun by insects or will pollution cause warming and decrease the insect populations? I guess the take home message is you are sure to lose either way. By the way, global cooling will also decrease insect (as well as human populations) and totally devastate our world.

On a local level, like your backyard, most population explosions are related to food supply and weather. Extreme conditions, like droughts and hurricanes, will cause fluctuations in populations. Cultural practices, like fertilization, irrigation and weeding, also impact insect populations. Once you identify a specific insect problem, then you can determine whether you or nature will allow it to thrive.

For an example of monitoring factors which affect aphid populations, visit http://www.rothamsted.ac.uk/corporate/annualreport/2000/4-Insect-Pop.pdf If you don’t have internet access, call me at 910-893-7533 or email me at gpierce@harnett.org

A swarm of locusts was predicted in the Bible. When Moses was bargaining with Egyptian Pharaoh Rameses II for the release of the Israelites, 3 of the 10 plagues were insect related – lice, flies and locusts. The locusts were number 8 in the lineup. While I’m sure they were devastating, number 10 was the death of the firstborn Egyptian children. Needless to say, the locusts plague was small potatoes compared to the “firstborn” plague. If you are having “biblical” populations of insects at your house, maybe you need to move before the plagues get worse. http://www.theholidayspot.com/passover/plagues.htm

Gary L. Pierce

Horticulture Extension Agent