This winter, articles and commentaries on coqui frogs have shown up almost as often as the frogs themselves. Despite quarantine actions on plants from infested areas, coqui continue to spread, and there are solid reasons why we should be concerned.

These Puerto Rican natives were first confirmed in Hawaii in the late 1980s, when state biologists investigated a report of new birds singing at night. At that time, there were no known methods or registered pesticides to control the frogs and no readily available pot of money to start the research and pesticide registration process. Furthermore, there wasn’t agreement that the presence of coqui warranted much concern or emergency action. By the time citric acid was registered for coqui control in 2002, they had spread to more than 262 locations on Hawaii island, 45 sites on Maui, two on Kauai, and more than 35 on Oahu.

Today, coqui are present in nearly every community on Hawaii island, and densities have reached 224,000 frogs per acre in some natural areas. The loud dusk-till-dawn mating call of male coqui have pulled neighbors together in control efforts, and apart in others where there is deep resentment that their neighbors made the choice for them. Essentially, if a neighbor has coqui, you do, too. In 2005 the presence of coqui became a disclosure requirement in real estate transactions, with real estate values declining within 500 meters of frog infestations.

As troubling is the impact of coqui on insects and other invertebrate populations, which is now very measureable at the landscape scale. Researchers from Utah State University found that 224,000 frogs per acre consume 1.7 million insects and invertebrates, resulting in a 27 percent decrease in forest floor insects. Although some people may not lament the loss of bugs, consider the fact that each plays a role in the normal functioning of the ecosystem, and this level of change is uncharted territory.

The good news is that other islands do not have to accept these impacts. The Maui Invasive Species Committee is working on eradicating coqui from Maliko Gulch, its last remaining large population. It and the Invasive Species Committees on Oahu, Kauai and Molokai help the state Department of Agriculture respond to coqui frog reports, so that these islands are largely coqui-free.

Required interisland quarantine treatment of nursery plants is not 100 percent effective. Therefore, the University of Hawaii College of Tropical Agriculture is working to develop pest management strategies to reduce coqui numbers in plant nurseries, thus decreasing the chances of movement on plants. However, coqui also take refuge on vehicles, outdoor furniture, construction materials and other items in infested areas, which give the frogs a free ride wherever they are transported. Recent coqui finds on each island prove their ability to hitchhike in unregulated merchandise and private property. Setting up a system to inspect every item shipped from Hawaii island is unrealistic, so the bottom line is that we must work together to make sure coqui do not become established in our neighborhoods.

If you import items from areas known to have coqui, or if you buy plants from your local garden shop, quarantine your purchases in a garage or other enclosed area for a few days and look and listen for frogs or other pests. Listen to coqui online to become familiar with their two-note call at www.hear.org. Coqui calls are sometimes confused with the greenhouse frog, which is widespread and not the subject of control work.

If you think you hear coqui, call the state pest hotline at 643-PEST (643-7378), or your island Invasive Species Committee.

A call that turns out to be crickets is better than not calling for a year.