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Some Hawaii pests arrived by invitation
Jan TenBruggencate
A lot of our worst pests get here by accident, like the mosquito arriving in a ship's water casks during the last century and the two-spotted leafhopper, whose arrival remains undocumented.
Mosquitoes make outdoor life a lot less comfortable, and are responsible for carrying diseases that kill off many native birds. The leafhopper is weakening many of our plants, particularly natives.
But perhaps the more frustrating pests are those that people bring in on purpose. Like bird-eating mongooses, brought in to control rats, and two forest weeds—the banana poke and blackberry—brought in as garden plants.
And the apple snail.
This pest has made a tour of the globe from its Argentine home, spreading problems with its travels, according to Bishop Museum mollusk expert Robert Cowie.
In Taiwan, where it arrived in 1980, the apple snail was imported to start an escargot industry. Instead it got into the rice paddies and became a serious pest.
The snails are a problem in Indonesia, Thailand, Cambodia, Hong Kong, southern China and Japan. They've shown up in Guam and New Guinea. In the Philippines, they became the top pest in rice fields.
Pomacea canaliculata, the apple snail, arrived in Hawaii in 1989, destined once again for the plate. A market never developed for the snails, although you can buy them in a few restaurants and markets.
While they may not have made it onto many dinner plates, they did find their way into taro and rice fields. The snails had already become pests on Kauai, Oahu and Maui in 1990 and 1991. The following year they reached Waipio's rice fields on the Big Island, and recently they were found in the man-made lake at Kauai Lagoons in Lihue.
Taro farmers have unleashed ducks on them applied pesticides to poison them, used vacuums to suck them up, picked them out by hand and even dried up the taro fields to discourage them.
"None of these measures has met with total success, although collecting of the snails by hand is said to reduce their numbers significantly," Cowie said.
Undaunted, the snails are moving farther.
"Apple snails are now beginning to be found in natural ecosystems. They pose a threat to Hawaii's wetlands," Cowie said.
He believes we often make the mistake of looking for short-term gains—like the establishment of a snail industry—without adequately considering what kind of damage the new species will do.
In this case, the fairly small potential of a local escargot industry is challenging a longestablished crop, taro, with a significant economic and cultural impact.
The Honolulu Advertiser, February 17, 1997
Jan Tenbruggencate is the Advertiser's Kanai bureau chief . He can be reached at (808) 245-3074.
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