Koa Bug

Coleotichus blackburniae
Koa Bug - Coleotichus blackburniae

The koa bug is a rare endemic “stinkless” stink bug found on the islands of Hawai’i, Maui, O’ahu, Kaua’i, and Moloka’i. Its iridescent, blue, green, maroon, and yellow coloring are unique identifiers of this endemic arthropod; measuring almost an inch in length, Coleotichus blackburniae is the largest native true bug of Hawaii. Historically, this species was commonly found on native koa (Acacia koa) and a’ali’i (Dodonaea viscosa). However, the Koa bug has also been known to be found on a common ornamental tree, the Formosan koa (Acacia confusa); although native to Southeast Asia, it has become naturalized and is invasive to Hawaii. Currently, the koa bug is rarely found in the State but does occur at Hakalau Forest. 

Information on the koa bug is scarce. Adults and nymphs feed on the fruits of native koa and a’ali’i, as well as the non-native formosan koa. Adult females lay their eggs on the leaves and fruits of these species, where the larvae develop for an estimated 38 days. Female koa bugs are estimated to live for 80 days and begin mating 30 days after hatching. Both larvae and adult koa bugs emit odorous defense compounds when disturbed.

The koa bug has no known natural predators; however, non-native spiders and ants are known to parasitize C. blackburniae eggs, nymphs, and adults. The big-headed ant chews koa bug eggs and Western yellowjacket wasps are predators of young. Other species known to kill koa bugs include Anastatus sp., Acroclisoidessp., and birds. In addition, two biocontrol agents (Trissolcus basalis and Trichopoda pilipes) that were introduced to control the southern green stink bug are able to locate and develop on C. blackburniae. Although these species have a relatively minor impact on C. blackburniae overall, substantial impacts may occur at individual sites.

 

The koa bug has also been impacted by the reduced abundance and distribution of its host species as a result of deforestation, agricultural activities and urban development. Because these plants typically fruit at the same time, locating host plants suitable to lay eggs may require C. blackburniae to disperse over long distances. Studies have shown that koa bug mortality due to dispersal accounted for about 50 percent mortality in all individuals studied.

Facts About Koa Bug

Scutelleridae is a family of true bugs commonly termed jewel bugs due to their iridescent coloration. 

 

Closely related to the family Pentatomidae, where members tend to release a foul-smelling defense chemical when disturbed, Koa bugs have been dubbed the "stinkless" stink bug due to a reduced potency of their malodorous compounds.