The Coqui Frog Invasion
Arnold Hara
University of Hawaii at Manoa
College of Tropical Agriculture and Human Resources
Hilo, Hawaii
What will this presentation cover?
* Invasive species crisis in Hawaii
* Impact on Hawaii’s environment
* Basic Biology
* Life cycle
* Video of single calling male
* Color variation
* What do they eat?
* Who has more coqui frogs,
Hawaii or Puerto Rico?
* Non-Chemical Controls
* Chemical Controls
* The Reality
Invasive Species Crisis in Hawaii
What is an Invasive Species?
= Any foreign, exotic, or alien species that
spreads aggressively to cause
commercial, agricultural, environmental
or human health harm.
Recent Invasive Species Affecting East Hawaii
Cardin’s whitefly 2003
(fiddlewood, citrus, plumeria)
Cycad scale 2000
(sago palm, queen)
Cotton lace bug 2001
(hibiscus, eggplant, orchid tree)
Giant Whitefly
2002 (hibiscus
fiddlewood)
Bearded!
Stinging!
Stinging!
Nettle caterpillar 2001
Little fire ant 1999
(palm, ti-leaf, iris, mondo)
Noisy!!!
Coqui frog 1990’s
Dec 2003
Impact of Coqui Frogs
Beneficial Insects:
natives
pollinators
parasitoids
predators
organic feeders
People’s sleep
Real Estate + and -
Irrigated
landscapes
In West Hawaii
Frogs will infest areas
with >60 inches of rainfall
and from sea level to
4000 ft. elev., almost the
entire East Hawaii.
Developing vacant
properties reduce frog
habitats. No sale due to coqui.
By Kim Tavares, BIISC
Basic Biology
*Unlike insects with hard outer shell, coqui take in water & oxygen through
their very thin, fragile skin.
*Internal body structure of a coqui frog is similar to humans and possess
similar organs including a heart, lung, liver, pancreas and kidneys.
*Coqui frogs live on a diet of insects.
*Coqui frogs are cold-blooded in that their body temperature depends
on the temperature of the surrounding environment.
*LOUD calling sounds are produced in the same way as humans yell,
by forcing air from their lungs over their vocal cords, located in the throat.
*Male coqui frogs provide parental care by guarding eggs from predators
and keeping the eggs moist.
*No tadpole stage, direct development from egg to frog.
Life Cycle of the Coqui
*No tadpole stage; no need for water, just moisture.
*Males guard eggs and keep them from drying out.
Cluster of eggs
Egg cluster size: 34 (17-75)
Clusters/female/yr: up to 26
Eggs incubation: 14 -17 days
Froglet
Mature
adult
Eight months
from egg to
egg-laying adult.
Adults live as
long as 4 to 6 yrs.
Vocalizing male coqui frog
vocal sac
J. Ballauer
The vocal sac inflate and act as resonating chambers, amplifying
the call. Two types of calls:
1) mating or advertisement call
2) aggressive or defensive call – defend territory from other males
Are these all Coqui frogs?
Brown w/o stripe
Brown w/stripe
&mottling
Light brown w/stripe &
smooth blend of yellow
Light tan w/ stripe
Yellow w/stripe &
dark brown mottling
Golden yellow w/stripe
& tan patches
Lighter brown w/stripe
& yellowish mottling
Light brown w/stripe
& yellowish mottling
Light tan w/stripe &
tinge of yellow
Light yellow w/stripe
& tan mottling
Brown w/o stripe &
tan grey mottling
Tan w/o stripe &
brownish mottling
Skin is very thin and sensitive to chemicals, heat or cold
eggs
Coqui Frog Egg Development (Days after laid)
1 to 2 days
8 to 9 days
3 to 4 days
5 to 6 days
10 to 11 days
13 to 14 days old
S. Chun
Frog Hatch
S. Chun
Nesting Sites are Abundant in Hawaii
Ti- leaf on plant
Fallen heliconia leaf
Nesting sites are hiding places in curled
leaves or debri that is dark and holds moisture
Frog snaps at grasshopper!
J. Ballauer
What do they eat?
*Cannibalistic - Eat themselves and their eggs!
*Starve over 3 months and live on moisture only!
Who has more frogs, Hawaii or Puerto Rico?
*Adult population in Hawaii is 4 to 6 times greater
than Puerto Rico.
*At Lava Tree State Park number of adults and
juveniles is estimated at greater than 10,000/acre.
Why is Hawaii’s Population Higher
than Puerto Rico?
• Lack of Predators (snakes, large spiders, lizards
and owls in Puerto Rico)
• Denser vegetation with more nesting and retreat
sites!
• More insects, more food supply!
Typical Coqui Frog Habitat in Puerto Rico
Hawaii’s forest has more retreat & nesting sites
Denser vegetation
Exposed roots of trees provide retreat sites
Lava rocks also provides retreat sites
Lava Tree State Park
Non-Chemical Controls
Capturing
*Cultural
*Trapping
*Temp.
Heat
Cold
*Biological
Behavior
Genetic
*Further discussion
Hand capture; requires practice
Habitat modification. Re-landscape to
minimize retreat and nesting sites
PVC traps
Hot water shower or vapor heat (113o F)
In reefer for 36 – 38o F for 6 hours
Predators and diseases (chytrid fungus)
Simulate male calling to attract females
Insert lethal or sterilizing gene into
coqui frog population (long term research)
Before
Coqui Frog Ground Zero!
Lava Tree State Park
Habitat Modification and Native
Plant Replant Project
During
After
Inmates from Hawaii Community
Correction Center provided labor.
Volunteers from Malama ‘0 Puna replanted
with donated native plants.
Collaboration:
County of Hawaii, DLNR, HDOA, USDA, UH
Covering rocks with cinders to seal habitat sites for frogs
Lava
Tree
State
Park
Frog habitat
Collaboration:
County of Hawaii
DLNR
HDOA
HCCC
Malama ‘O Puna
USDA
UH
Frog habitat
PVC Traps
1” PVC trap with “T” fitting
1” PVC
w/eggs &
male
* 1” PVC provides nesting site
*Trap efficiency is 19-28% in
tests at Lava Tree State Park.
*PVC needs to be weathered.
*Mass trapping will be tested.
Hot Water Shower for plants
Instant water heater
Temp
Controller
*Treated at 113 F for 3 min kill frogs.
*Plants are not detrimentally affected.
*Plants are treated immediately prior
to shipping.
*Hot-water shower system installed
at the Division of Forestry & Wildlife,
Tree Nursery in Hilo for forest
seedlings.
Eggs Dipped in Hot Water
109o F for 3 min
Treated
(Cooked)
Untreated
(Uncooked)
Temp & Time Required to Eliminate Egg Hatch
109o F <3 min
113o F <2 min
Chemical Controls
Caffeine
Not Available. Emergency registration has expired.
Hydrated
Lime
Hawaii Dept. of Agriculture has applied for special
emergency registration. Legal to apply as a soil
amendment. A 25-50 lb per 100 gal mixture kills frogs as
a drench application to the ground during the day.
Citric Acid
Legal and effective in tests at (1.3 lb /1 gal. 16%). Burns
certain foliage and flowers (ferns, papaya, mock orange,
orchids). Application in the evening when frogs are
active.
Pyrethrins Will drive frogs out of hiding; they often recover from this
(Raid H&G) toxicant.
Citric Acid and Pyrethrins: 8% citric acid plus pyrethrins is effective
and will not injure plants.
Citric Acid
Degree of tolerance of tested plants to 16-25% citric acid spray
Tolerant to Citric Acid:
Dracaena fragrans
Palms:
Areca
Dracaena warneckei
Fishtail
Philodendron
Rhaphis
Syngonium
Parlor
Ti plant
Phoenix
Triangle
Sensitive to Citric Acid:
Anthurium
Mock orange
Bromeliad
Passion fruit
Citrus
Papaya
Calathea
Streptocarpus
Guava
orchid
Leather leaf fern
Washing with water one hour after spray
will eliminate burning.
Also sold in dry form
5 lb = $9.00
Experimental Drench Application of Hydrated Lime
Koa’e (Kapoho) Community Association 1000 gallon
Drencher with a high volume firefighting pump.
High volume firefighting nozzle
Effective day treatment by concentrating high volume applications to retreat areas
on the ground.
Biological Control of the Coqui Frog
Predators:
Rat
?
?
Confirmed!
Mongoose?
Confirmed!
Others?
Hawaiian Hawk?
Brown Tree Snake now has lots of coqui frogs as
prey or food to thrive in Hawaii!
Hawaii 2050
The Reality
*Coqui frogs will continue to expand on the Big Island!
*No known effective biological control agent (predator,
parasite, disease).
*Coqui frog populations will be limited only by lack of food
supply and nesting sites.
*Some community groups have been successful in controlling
coqui (Kohala, Pahala, Kapoho, Komohana Gardens). The
sooner 1 or 2 frogs are captured in a new area, the chance
for success is greater.
*Government (County, State, Federal), private landowners,
and plant nurseries must do their share in coqui control on
their property and plants for sale.
Acknowledgements
For assistance:
Joshua Ballauer
Francis Benevides
Cynthia Carey
Clive Cheetham
Stacey Chun
Eunice Domingo
Myrtle Hara
Trent Hata
Chris Jacobsen
Meg Jones
Dennis Ida
Beryl Iramina
Ryan Kaneko
Curtis Kataoka
Irving Kawashima
THANK YOU!!!
Billy Kenoi
Eloise Kilgore
Mayor Kim
Angel Magno
Bill Mautz
Larry Nakahara
Ruth Niino-Duponte
Tim Ohashi
Kyle Onuma
Lance Ogata
Rosey Rosenthal
Rene Siracusa
Rick Speares
Kim Tavares
Marcel Tsang
Shayne Veriato
Larry Woolbright