Insects

Observations and Collections

With the assistance of grant-funded studies and ongoing field observations, ecologists have identified over 1,100 insects on Forest Preserve District land and have collected over 750 moths from several locations for study specimens.

Butterflies and Dragonflies

In collaboration with the Butterfly Monitoring Network and the Peggy Notebaert Nature Museum in Chicago, Forest Preserve District staff and volunteers survey butterfly and dragonfly populations in 17 forest preserves. Monitors have observed several rare or habitat-dependent species, including the Bysuss skipper, pipevine swallowtail, and Edward’s hairstreak. To view the most recent surveys, download the Butterfly Monitoring Program Summary or the Dragonfly Monitoring Program Summary.

Hine’s Emerald Dragonfly

Waterfall Glen Forest Preserve in Darien is one of a few places worldwide where the federally endangered Hine’s emerald dragonfly lives. To successfully mate and reproduce, the Hine’s emerald dragonfly depends highly on groundwater-fed springs where dolomite and limestone bedrock are close to the soil surface. Unfortunately, in the past 50 years, development, erosion, invasive plants and drainage from groundwater wells have degraded much of this unique habitat.

As a result, the Forest Preserve District is working with other government agencies to develop new breeding habitats next to the established sites at Waterfall Glen and has entered into a Safe Harbor Agreement with the Illinois Department of Natural Resources and the U. S. Fish and Wildlife Service.

Ticks and Lyme Disease

Forest Preserve District ecologists have used reports from both the public and District field personnel to monitor the presence of deer ticks in DuPage County. The deer tick is the species that can carry Lyme disease. Now that the DuPage County Health Department has identified Lyme disease in DuPage, the Forest Preserve District is working to educate visitors about ways to avoid tick bites.

Additional information on ticks in Illinois is located on the Illinois Department of Public Health’s Web site at www.idph.state.il.us/envhealth/pccommonticks.htm.

Mosquitoes and West Nile Virus

Under normal conditions, the Forest Preserve District does not engage in extensive mosquito-control efforts. Mosquitoes are an important part of the food chain, and natural predators keep populations in check. Mosquito larvae help local waterways by filtering up to two quarts of water each day.

Since 2003, however, the District has conducted a West Nile virus mosquito-management program to specifically target the Culex mosquito — the genus most likely to transmit West Nile virus — in order to reduce the threat to public health. The District’s monitoring program is one of the most extensive sampling and monitoring efforts in DuPage County.

Trained District personnel monitor over 200 sites in close proximity to high-use public areas each week from mid-May to the first frost, which is typically in October for Culex larvae. If larvae are found, or if adult mosquitoes are found that are carrying West Nile virus, the District treats those areas with a larvicide. District employees work to locate and address areas that could potentially hold stale, stagnant water such as truck beds, dumpsters, buckets, and gutters. Additionally, the District collaborates with state, county, and local health departments and shares developments with the scientific community across the country.

Additional information on mosquitoes and West Nile virus in Illinois is located on the Illinois Department of Public Health’s Web site at www.idph.state.il.us/envhealth/wnv.htm.

Gypsy Moths

The gypsy moth is an invasive European species. During the caterpillar stage, gypsy moths can defoliate entire trees. They feed on hundreds of species but most often on oaks. Continual attacks can fatally weaken trees or leave them vulnerable to other insects or disease.

As the gypsy moth moves west, it is becoming established in areas throughout Illinois, and unfortunately, it is here to stay. As a result, since 2007, the Illinois Department of Agriculture has placed DuPage County under quarantine, which restricts the movement of woody plants, timber products, such as firewood, and other materials.

Although it can never completely eradicate the gypsy moth, the Forest Preserve District has implemented a three-point program to suppress infestations. Staff survey forest preserves across the county for the presence of gypsy moths. In winter and early spring, crews treat egg masses on hundreds of trees with dormant oil in order to minimize caterpillar populations. If funding allows, the District may also treat infested areas in the spring with a biologically derived pesticide called Bacillus thuringiensis kurstaki, or Btk, which is made from a bacterium that naturally occurs in the soil. The bacterium is harmful to gypsy moths but is not toxic to humans or pets.

Additional information on the gypsy moth in Illinois is located on the Illinois Department of Agriculture’s Web site at www.agr.state.il.us/Environment/Pest/gypsymoth.html.

Emerald Ash Borers

The emerald ash borer is a nonnative beetle that has destroyed over 20 million ash trees in the Midwest. Arborists discovered the beetle in DuPage County in 2007.

Adult emerald ash borers appear between May and July. They fly within 6 feet of the ground, feed on leaves, and crawl on branches and trunks. The females lay their eggs, and the larvae hatch seven to 10 days later. The larvae feed extensively on an ash tree’s inner bark, destroying its ability to move food from its roots to its leaves. Infested ash trees have thinning, yellowing crowns and epicormic branches that sprout from the base of the tree or along the trunk. D-shaped exit holes in the bark confirm an infestation.

The Forest Preserve District has worked closely with the Illinois Department of Agriculture and other state and federal agencies to monitor this destructive species and to keep abreast of the latest eradication techniques. “Trap trees” designed to attract any nearby borers are in several forest preserves. District foresters inspect the trees annually to find new infestations as quickly as possible. As another preventative measure, the District has prohibited the use of outside firewood in its campgrounds and picnic areas. To date, the emerald ash borer has not been identified in DuPage County’s forest preserves.

Additional information on the emerald ash borer in Illinois is located on the Illinois Department of Agriculture’s Web site at www.agr.state.il.us/eab.