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"Maybe I should write about crickets?" I asked.
"Is there enough stuff to write an article on crickets?"
Cindy responded. In answer I pulled down Daniel Otte's
The Crickets of Hawaii, a 400 page tome on the Orthoptera
of our fair islands. Filled with dozens of pages of cryptic
graphs and close-up photos of cricket legs, abdomens,
and heads, Otte's book is not a captivating read. But
Hawaii's crickets do have a fascinating and spectacular
natural history. Their story of colonization, speciation,
and adaptation rivals that of any of Hawaii's other more
"famous" evolutionary creatures. And of course,
the study of Hawaii's crickets is loaded with noteworthy
anecdotes.

A
plate from Otte's book
showing Hawaiian crickets
Crickets
can be hard to find. Have you ever searched in vain for
that chirping cricket in the corner of your bedroom? Loud
and clear it calls but you can't find it. Because of the
cricket's natural stealth and incessant chirping, a Hawaiian
myth of the "singing snails" persisted for decades.
Once the islands' forests were full of tree snails. The
snails were so numerous that they were easily seen to
the most casual observer. Along with the snails the forest
visitor also heard a continuous song of chirps and trills.
There didn't seem to be anything other than snails to
make the music so folks assumed it was snails singing.
If people had taken the time and care to closely inspect
the tree bark, tiny crickets known as Laupala or Prolaupala
would have been discovered. It is the cricket's daytime
pulsing chime that the snails were credited with creating.
Both
the Laupala and Prolaupala are swordtails (Trigonidiinae.)
And, like all of the native crickets except for one, they
are island specific. Hawaii has three large groups of
crickets. Along with the swordtails, there are tree crickets
(Oecanthinae) and ground crickets (Nemobiinae.) When Otte
first began to study the Hawaiian crickets in 1968, he
thought he could "do the crickets of at least several
islands" while on short stopovers to his systematic
research project in Australia. He quickly found that a
more intensive and systematic effort was needed. Over
the next couple decades Otte, with the help of a Maui
native, Robin Rice, discovered a stunningly diverse population.
There are now over 240 named species of Hawaiian crickets
or twice as many as in the continental U.S.
Otte
speculates that all the Hawaiian crickets came from four
original colonizing species. The colonizers were probably
all "flightless species that arrived in Hawaii as
eggs deposited in floating vegetation." Once they
rafted ashore the eggs hatched and the evolution of Hawaiian
crickets began. From these first cricket founders new
species diverged and adapted. The swordtails are by far
the most speciated of our crickets. From a single genetic
colonizer more than 150 species evolved; 31% of the world's
swordtails are Hawaiian. For the most part the Hawaiian
Trigonidiinae have stayed true to the form and function
of their cosmopolitan relatives. They generally live on
vegetation such as weeds, sedges, and ferns and some are
mute and flightless. On the other hand, the Hawaiian tree
crickets changed and transformed in impressive ways. From
a single ancestral tree cricket colonizer Hawaii now has
43% of the world's known tree cricket species. Some of
the derived Hawaiian species have evolved traits and adapted
niches that elsewhere in the world are representative
of other cricket families. Some of our tree crickets have
become ground dwellers or live under bark or in hollowed
twigs. Some have become like the swordtails, mute and
deaf, having lost all traces of the anatomical structures
that allow them to sing and listen. And some have moved
underground to become blind and colorless cave dwellers.
Cave Cricket
(Photo by Bill Mull)
Actually,
the very first troglobite or true cave creature discovered
in Hawaii was a cave cricket, a Caconemobius. Besides
the astonishment to the scientific world that troglobites
could evolve in Hawaii, the entomologists were also puzzled
about the ancestral source of the Caconemobius. This cave
cricket was discovered in 1971. It wasn't until 1979 that
Otte and Rice discovered a shore cricket hopping away
among the wet rocks of the Kalapana coast. With that discovery
"the puzzle of how cave inhabiting Caconemobius could
have originated was effectively solved." These coastal
ground crickets kept moving inland on the lava through
cracks, crevices, and caves and became isolated within
lava flows. Once isolated they changed and speciated,
some eventually finding their way underground.
I
remember my first view of a cave cricket. Pure translucent
white, no eyes and with an antenna twice as long as the
body, the cricket was obviously a special and rare creature.
I've seen only three in my nine years in Hawaii. I also
remember once sitting on the forest floor at Manuka amidst
a carpet of plant litter. Staring down it took a moment
before I noticed a tiny movement. I focused closer and
discovered dozens and dozens of very small crickets moving
through the debris. There was no chirping nor trilling.
As I crawled about looking for more I realized that thousands
of crickets were around me. Every inch of leaf litter
was inhabited by the Orthopteran natives. All descendents
of crickets that long ago were tiny egg castaways looking
for a home.
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