Environmental Almanac

Entomology student publishes update of 1927 ant survey

Andrea Belcher's "Urbana House Ants 2.0" replicates older study to compare present with past
Close-up of a blackish and and a red ant fighting.

Carpenter ants of two different species locked in combat. Selina Ruzi

Andrea Belcher came to the University of Illinois five years ago as a graduate student to study ants with entomology professor Andrew Suarez. In her own words, she was “always interested in small things,” and the research opportunities she took advantage of as an undergraduate in her native Texas led her to focus on ants.

In contrast to many other young biologists, who are drawn to genetic studies and lab work, Belcher was especially interested in the study of her subjects in the field.

That made her an ideal candidate for a project department head May Berenbaum had been hoping to have someone take on, which was to replicate a study of ants in and around homes in Urbana done by a U of I PhD student in the 1920s.

Belcher’s article describing that project is published in the Fall 2016 issue of American Entomologist, under the title “Urbana House Ants 2.0: Revisiting M.R. Smith’s 1926 Survey of House-Infesting Ants in Central Illinois After 87 Years.”

Belcher’s survey had three goals: To identify ant species that infest houses now, to analyze the methods people use to control pest ants, and to compare her results with those found by Smith.

Following in Smith’s footsteps, literally, Belcher focused her study on two intersecting streets that form a cross in central Urbana, an area that encompassed about 300 single-family homes, as well as 40 multi-unit buildings.

Like Smith before her, Belcher relied on the cooperation of residents in the study area. First, she asked them to become “citizen scientists” and collect any ants found within their homes. This was done by capturing the ants on sticky tape and recording some basic information about them: where they were found, how many there were, if and what they were eating and what, if any, measures were used to control them.

In addition, Belcher sought permission from residents for herself and an assistant to walk around their yards once and collect any active ants they found to help determine the total diversity of ants in Urbana. Beyond that, Belcher sampled ants from three nearby fragments of forest, to allow for some comparisons between them and the urban setting.

What changed for ants in Urbana over the 87 years between Smith’s and Belcher’s studies?

Fewer species seem to be inhabiting human residences. Belcher turned up only eight, whereas Smith had 11.

An exotic species, pavement ants, seem to have spread into or increased in abundance in Urbana. They were the fourth most commonly collected species in residences in 2012-2013; Smith had found none of them.

People have adopted safer, more selective methods for chemical control of insects indoors. Survey respondents in the 1920s used broadly toxic chemical controls including compounds containing arsenic and mercury. Respondents from 2012-2013 reported using targeted, “least toxic” compounds, frequently baits that workers carry back to the nest.

Some decline in the total number of local ant species may have taken place. Despite sampling more habitats using a greater variety of methods, Belcher found only 44 species whereas Smith had 47.

For the present, Andrea Belcher’s work no longer focuses on ants. With a spouse in the military, she has landed in Santa Cruz, California, where she works primarily as an interpreter and tour leader at Natural Bridges State Beach. Insects are still part of the picture for her though, as she also assists researchers studying the monarch butterflies that overwinter there.

She, Berenbaum and Suarez all hope her study inspires other entomologists to examine the archives at their own institutions for studies from the past that might be replicated to help us understand how the insect world has changed over time.