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Science on Tap presents ‘Insects: Tiny things that run the world’

April 17, 2020 by Beckie Gaskill

Recently Patrick (PJ) Liesch spoke with the Science on Tap group about bugs, calling insects the “tiny things that run the world.” Insects are important for a variety of reasons, he said. Liesch is a statewide entomology specialist with the UW-Madison Department of Entomology.  

Liesch told attendees the only places without insects are the middle of the ocean and the north pole. Other than those two areas, some type of insects can be found everywhere on the planet, even in Antarctica. A comprehensive list of animals on the planet would show a total of approximately 1.5 million species. Of those, approximately 1 million, or 70% are insects and other anthropods. Beatles, he said, have the highest number of different species. In fact, he told the group, one out of every four animals on the planet is some form of beetle. 

Insects perform a number of essential tasks, including breaking down organic material. This includes breaking down dead animals and decaying plants, returning those nutrients to the soil.

He also spoke about insects as parasites and parasitoids. Good parasites, he said, do not kill their hosts. While there are many insects in this category, there are also a large number that are parasitoids. Those are parasites the kill their hosts. There are also a class he called hyper-parasitoids. Those are insects that infect and kill the parasiteoids. 

From there, the species get smaller and smaller. Liesch spoke about one species of wasp that is the same size as a single-celled amoeba. While this particular insect is that small, it is no different than a bigger wasp that is seen on the landscape every day. It has a brain, cells, a head, a body, wings, legs and all of the parts one would expect to find on any insect. Parasitoids, he 

said probably have more species than even beetles, but due to the difficulty in studying them, there are likely many species that have yet to be discovered. 

“We know of a million,” he said of these smaller species, “but there are probably three, four, five million.”


Liesch also spoke about the importance of insects as pollinators. Approximately three quarters of plant crop species depend on some type of pollinator. Grocery stores, especially the produce section, he said, would look much different without pollinators. He specifically pointed out two items, coffee and chocolate, that would not be available without pollinators. While this brought a chuckle from the audience, he made it clear how important insects were as pollinators to the food humans eat every day.

From there he turned to the food web in general. Most insect species make up a large portion of the lower level of the food web. He told the group the majority of vertebrates on the planet either directly or indirectly feed on insects. With insects as the base of the food web, they are important to preventing the collapse of the food web, and life in general.

In recent decades, Liesch said, there has been a decline in insects, with some populations collapsing. The decline, though, is difficult to study, and obtaining a grant for such study is almost impossible. In order to truly follow population trends and make determinations about what may be the cause of increases or decreases, the species need to be watched for long periods of time. Grants and other funding, he said, are usually available for projects to be completed in two to five years. Insect study, he said, could take from 20-30 years.

There are many reasons insects are facing difficult time, he said. One of those is land use changes. Landscapes are becoming more fragmented. Agriculture, urbanization and light pollution all contribute to the noticed decline in many species. Invasive species, too, can cause declines in native insect populations.

Liesch said he has been seeing two to three new non-native insect species per year in the state. While many of them do not cause widespread issues for native insects, others do. Occasionally, he said, he will see an invasive like the gypsy moth or the emerald ash borer, that has very wide-ranging implications for many species. Often, too, non-native or invasive species will outcompete native insect species, disrupting the food web to at least some degree. Changes such as this can be more difficult to track until population declines and collapses are found.

How to help

Liesch spoke with the group about things that could be done to help the plight of insects in the state. One of those is to increase the diversity of plant species on the landscape. Some insects, he explained, are specialists and need only a specific species of plant for parts of their life cycle. Having a variety of native plants on the landscape increases the diversity of insects, creating a healthier, more robust environment in total. He also cautioned about purchasing flowering plants simply for their look or the color of their bloom. Native flowering plants, he said, are always the best choice where native pollinators are concerned. 

Other things gardeners and land owners can do to help insect populations is the reduce or eliminate pesticide use, using these things only when absolutely necessary. Light pollution, too, could be limited, he said. Some insects only perform their necessary functions under the cover of darkness. Too much light in a yard or other area can disrupt this. Keeping some of these simple things in mind when planning garden spaces and outdoor areas, he said, can go a long way toward improving the situation insects face in our current environment.

Beckie Gaskill may be reached via email at [email protected]

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