Coqui Frogs in Hawaii

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coqui1You’ve heard the noise at night in certain areas of the Big Island. The incessant loud chirp, chirp, chirp of the invasive coqui frog. A single frog the size of a quarter emits a mating call that is 90 decibels, the intensity of a lawn mower. Multiply the sound by hundreds of frogs and you have a chorus of cacophony that can keep you awake all night. A single frog outside your window can be even more tortuous and tedious than a chorus of frogs. On the other hand, some people have grown accustomed to the sound of frogs and aren’t bothered by the din.

In the last 12 years, enormous colonies of frogs have taken over vast swaths of the Island, starting in Puna and the East side and spreading out from there. In many areas of the Big Island, residents have flown the white flag of surrender in battling the coqui frog, simply giving up on the inevitable invasion that keeps expanding and expanding into more and more neighborhoods and open spaces with no end in sight. Many residents and neighborhoods have abandoned any effort in trying to exterminate them, but that doesn’t mean you should. You can keep frogs from multiplying in your yard and neighborhood by being vigilant the minute you hear a stray frog.

In battling frogs, you should first understand their behavior, life cycle and habitat. First and foremost, it’s the male frog that does the chirping, tending to be more vocal during the rainy season or wet weather. During the dry season, you might not hear as many frogs chirping, but that doesn’t mean they are are inactive or not reproducing. In the course of a year, a single mating pair of coqui frogs can produce over 1,400 offspring. A single clutch of eggs can yield between 15 to 50 or more froglets. It takes two-and-a-half weeks for a clutch to hatch. It’s the male frog that guards the clutch. When guarding a clutch, the male frog will not be chirping. An adult coqui frog can live for four to five years.

Coqui frogs generally occupy bushes and trees, hiding out in the interior of leaves, in leaf litter or on twigs and branches. During the day, they are known to travel from their perches down to ground level, seeking protection or moisture in leaf litter, or feeding on insects (coqui frogs do not eat mosquitoes, however, according to laboratory studies). The male coqui frog is very territorial. It will return to the exact same spot for months on end, even years. Even if it hops away for some reason (such as if it is startled), it will go right back to the same exact area and continue with its chirping through the night.

How does a single frog end up in your yard? The most likely culprit is your gardener, who probably brought the hitchhiking frog with him on his truck filled with green waste from an infested property. Another possibility is that it arrived in an infested potted plant that you bought at the nursery or was given to you by a friend. A third possibility is that it hitchhiked on a friend’s or your own vehicle that had previously been parked in a coqui-infested area. A fourth possibility could be that a frog jumped into your yard from a passing car filled with green waste on its way to the transfer station. A fifth possibility is that floodwater has transported frogs and eggs from another property onto yours. Regardless of where the frog came from, it is imperative that you hunt it down and kill it ASAP.

Two substances are used in Hawaii to kill frogs: Baking soda or citric acid. Citric acid is available at farm and garden stores. It must be mixed with water and used in conjunction with a sprayer. Baking soda in large bags is available at Costco. For hunting a single frog, the baking soda method is easiest and best. A frog coated in baking soda will not survive. Take a paper cup of baking soda with you on your hunt, along with a flashlight. For increased success, two people searching together will yield faster results. Frogs tend to throw their voices, so it can be challenging to echolocate a frog. Try to isolate the general vicinity of the sound and carefully work your way into the foliage, gently pulling back each and every leaf to inspect the interiors. Oftentimes a frog will sound like it’s overhead when it’s actually at eye level. It takes patience to locate a frog. If it stops chirping, turn off your flashlight, wait a few minutes for it to resume chirping, and then continue with your search.

The good news is that the coqui frog, when located, tends to freeze in place for a few moments. This gives you plenty of time to gently toss a coating of baking soda onto the frog. The coated frog may hop away, but that doesn’t mean you haven’t killed it. Once it comes in contact with the baking soda, it will not survive for long. Another method is to pour baking soda all around the ground and around the trunks of bushes and trees in hopes that the frog will travel across the residue during the day when it comes down from its perch. If you are adverse to the baking soda method, you can always hand capture the frog, put it in a baggie and place it in your freezer to die a less painful death. Some residents use a clear tube to capture the frog and relocate it. If you have more than one frog in your yard, it could indicate a breeding situation going on.

Vigilance is key when combating coqui frogs. It may seem frustrating or impossible at first, but with a little bit of concerted effort, you can keep your neighborhood quite and coqui free.