State officials said today that they have held up about half the container shipments of mainland Christmas trees because they are “widely infested” with non-native pests including banana slugs, which can carry the rat lungworm parasite.

Shipments of Christmas trees from the Pacific Northwest are being held for treatment by the Plant Quarantine Branch of the state Department of Agriculture, officials said.

“As of today, agricultural inspectors have inspected 150 shipping containers of Christmas trees and wreaths from six maritime voyages. Of the 150 containers, 74 were or are being held for pest identification or improper paperwork,” the department said.

According to the department, of those 74 containers held:

>> Six have been treated and released

>> 15 were released due to low risk pests of pests that are already found in Hawaii

>> Four were sent back to the shipper at the shipper’s request

>> And 49 are being held pending treatment. 

Infested containers are being treated either by shaking each tree in the container or by hot-water treatment, depending on the type of infestation, officials said. Trees with wasp infestations are being shaken, while the hot-water treatment is being used for slug infestation.  

“The department realizes that Christmas trees are a treasured holiday tradition,” said Carol Okada, manager of the Plant Quarantine Branch.  “We are doing our best to treat and clear the trees as soon as humanly possible.”   

The shippers are being required to provide labor power to unload, shake and reload Christmas trees under the inspectors’ supervision, state officials said. 

They said that the concern about the slug infestation is that they may carry the parasite Angiostrongylus cantonensis, or rat lungworm, which causes a disease that affects the human brain and spinal cord.