Hawaii Pests

There are six new invasive species landscapers in Hawaii should know about. The Small hive beetle, Naio thrips, the Varroa mite, Erythrina gall wasp, Ohia rust and the Nettle caterpillar.

The Small hive beetle, roughly one-third the size of a honey bee and native to sub-Saharan Africa was discovered on the big island this year. It feeds on wax and honey in hives, destroys comb and causes fermentation of honey. It can be controlled by mechanical traps and pesticides. Biocontrol (introducing a predator) is being researched.

The  Naio thrips is a 2-mm-long insect, either from New Zealand or Australia (unknown). It was discovered on the Big Island. The thrips has had a severe effect on the ornamental landscape plant naio; it feeds on its leaves, causing them to form heavy galls. The concern is that it will move into native naio forests. What’s being done: chemical control.

The Varroa mite, a pinhead-size, red, crablike mite, native to Southeast Asia. It was discovered in Oahu and the Big Island. It kills wild and managed bee populations by sucking the blood from honey bees and their young. What’s being done: chemical control, traps, cultural controls and biocontrol is in research.

The Erythrina gall wasp is a gnat-size, brown insect with wings, native to East Africa. It was discovered in  Oahu,  and has spread statewide. It feeds on non-native and native erythrina trees (including wiliwili), causing the leaves and stems to form galls, which halt normal plant functions. What’s being done: a natural enemy wasp was released.

Ohia rust is  a microscopic fungus, likely from Florida, that was discovered in Oahu in 2005, and has spread statewide. This particular strain of rust affects plants in the myrtaceae family (of which ohia is one) and has caused huge die-offs of the rose apple. The concern is that another strain will arrive and affect native ohia. What’s being done: No known treatments or control measures available.

The Nettle caterpillar is  a sluglike caterpillar with spines, originally from Southeast Asia that was discovered on the Big Island, Oahu and Maui. It has stinging spines that cause pain and symptoms similar to man-of-war. It is found on plants—grass, ti, palms—common in yards. What’s being done: chemicals and biocontrol; a tiny wasp that feeds on nettle caterpillars was released in 2010.