News reports in The Advertiser last week about the invasion of the Erythrina gall wasp and its threat to the wiliwili family of trees brought several questions from worried readers.

A Honolulu woman called to say her 'ulu (breadfruit) trees were dying off and wondered if this new pest was responsible. Another caller reported she had discovered a wasp or beehive in her backyard and wanted to know what to do. A third reader sent an e-mail describing the bees infesting the building next door.

Is there any connection between their concerns and this wasp?

Nope; this is a whole new critter — although it has been busy as a bee.

The Erythrina gall wasp damages only the leaves of the Erythrina family of trees, which include the native wiliwili, the Indian coral tree and the tall wiliwili.

This particular wasp was unknown until last year, when specimens were identified in Singapore, Mauritius and the Reunion Islands. It has since been found damaging trees in Taiwan, and is believed to have reached Hawai'i in a shipment from that island nation.

The wasp was found in Manoa in April, but has since spread to Kaua'i, Maui and the Big Island.

While this bug has gotten a fair amount of publicity of late, it's doubtful you'll ever see one yourself. That's because the male is about the size of a grain of sand, and the female isn't much bigger.

But don't let its small stature fool you. Without a predator to keep its population in check, the wasp's numbers have exploded, allowing it to run amok on erythrina trees.

It lays its eggs on the young leaves. The larvae feed and mature in the leaf tissue, causing the trees to develop gall deformation. After awhile, the adult wasps exit through a small hole and the cycle begins anew — only in larger numbers.

Scientists say heavily infested trees stop growing, lose their vigor and may die.

What can you do?

Not much, apparently — especially if you're on O'ahu, where the wasp seems to have spread to all corners of the island.

On Maui, officials are still deciding whether to fight back with a plan that involves trimming and mulching infested leaves, and throwing them under a black tarp so the heat can cook the larvae. If the control effort goes forward, crews probably will be asking private landowners for permission to trim their Erythrina trees.

In the meantime, University of Hawai'i cooperative extension offices on each island are a good source of advice on garden pests.

If you have a question or concern about the Hawaiian environment, contact Jan TenBruggencate at jant@honolulu advertiser.com or (808) 245-3074.