The state Department of Agriculture has tried twice to recruit replacements. It is not trying a third time, according to Domingo Cravalho, the inspection and compliance section chief in the Plant Quarantine Branch.

"We want our dogs back," Warren Watanabe, president of the Maui County Farm Bureau, told The Maui News.

Human and canine inspectors attempt to keep travelers and cargo shippers from bringing in pests and diseases that can devastate crops — or attack native plants, like the wiliwili trees that have been nearly eradicated by a foreign wasp.

Departing passengers are inspected to protect California farmers, but that is a federal responsibility.

Cravalho said he has several open positions for inspectors at Kahului with or without dog-handling responsibilities. With several retirements in sight, he will have more.

For the Honolulu and Hilo airports, "there are more than enough applicants," Cravalho said. But at Kahului, he said, the scheduling to cover seven days a week is unattractive. Lihue and Kona also don't get recruits.

Inspectors need a bachelor of science degree in some area of biology, with core courses in entomology, botany and plant physiology.

The dogs are very effective at spotting even the former presence of plant materials. As an example, a tourist from Germany packed a sandwich with lettuce and ate it over the Atlantic Ocean.

When she landed in Kahului, the dog knew.

"The dogs are a useful tool," said Cravalho from his Honolulu office Tuesday.

Several "blitzes" at the airport have shown that most pests come in cargo rather than luggage. Organic produce is a particular culprit.

A new air cargo building is expected to be ready in August. That will provide a more convenient and secure processing facility than is available now, with freight containers opened on the pavement without any containment to slow down pests that may escape.

"That will help reduce risk," Cravalho said.

For passengers who may tuck a forbidden fruit or plant into their luggage, "we need to ramp up our public awareness and outreach," he said.

Enclosed cargo inspection and more inspectors were among the demands of Mauians who sued the state over environmental impacts at the airport.

Lawyer Isaac Hall, who represented the plaintiffs, got a settlement agreement that called for "best efforts" to increase inspections but no particular minimum of inspectors.

"We're very disappointed that the state Department of Transportation hasn't kept its agreement to protect Maui from alien species introductions," Hall said.

Applicants can find job postings at the state human resources Web site.

There is continuous recruiting for inspectors, with and without skills in handling canines, because of frequent openings.

The dogs could not be left on Maui after their handlers moved to Oahu, because they need regular work to keep their noses tuned.