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October 1, 2001

EPA Approves Use of Caffeine to Combat Coqui Frog Problem

Honolulu - The U.S. Environmental Protection Agency (EPA) has approved a specific exemption from the Federal Insecticide, Fungicide and Rodenticide Act, which will allow the use of caffeine to control coqui frogs in Hawaii. The Hawaii Department of Agriculture (HDOA) requested the exemption after tests by the U.S. Department of Agriculture personnel indicated that caffeine was an effective agent in killing coqui frogs, an invasive species known for its piercing mating calls.

The EPA action allows the use of caffeine only by pesticide applicators certified by HDOA. Permits from HDOA will also be required for areas to be treated with caffeine. Individual homeowners are not allowed to use caffeine to control frog populations due to certain risks associated with its use.

Those particularly susceptible to caffeine hazards include:

  • Toddlers and infants under the age of two,
  • Pregnant women,
  • Children taking medications for asthma or attention-deficit disorder, and
  • Individuals with a history of heart disease, high blood pressure, or circulatory problems.

Under the EPA order, HDOA can apply caffeine on a total of 2,000 acres of natural areas, nurseries and in ornamental plantings near residences and resorts. HDOA is also required to systematically monitor the effects of caffeine application on other "non-target organisms," including insects, birds, mammals, reptiles, amphibians and humans.

"The judicious use of caffeine, along with hand collection, habitat modification and other chemicals will enhance our ability to control the coqui frogs," said James J. Nakatani, Chairperson, Department of Agriculture.

Homeowners who think they hear coqui frogs in their yards at night should go out with a flashlight and capture them by hand or use a jar with a lid to contain the frog. The coqui is non-toxic. Do not transport the coqui from the area. Call the HDOA Pest Hotline immediately at the following numbers:

Oahu - 586-PEST (7378)
Big Island - 974-4000 ext. 67378
Maui - 984-2400 ext. 67378
Kauai - 274-3141 ext. 67378
Molokai & Lanai - 1-800-468-4644 ext. 67378

The coqui frog is small light-brown to dark-colored frog measuring up to two inches. Native to Puerto Rico, the coqui remain hidden during the day and emerge into the trees at night. The mating call of the male coqui is similar to a two-note bird-like chirp or whistle that sounds like, "ko-kee." Mating calls start at dusk and may continue throughout the night. There are no natural enemies to control the coqui in Hawaii. Populations may exceed 10,000 frogs per acre, which consumes more than 50,000 insects each night. As such, the coqui may likely compete with Hawaii's native birds that eat insects and also endanger native insect populations.

The shrieking courtship noise has been a major nuisance to many Hawaii residents and visitors, who are not able to sleep due to the noise level. As a distance of one foot, the loud, piercing calls (90 - 100 decibels) are comparable to the noise produced by a lawn mower, table saw, or helicopter.

Since the coqui remains hidden during the day, the movement of household potted plants has been associated with its spread. Those who purchase potted plants, especially bromeliads, should examine the plant and the medium carefully to make sure that it is free of the coqui frog.