controlling crb with a biological insecticide

How to Control Coconut Rhinoceros Beetle with Metarhizium anisopliae

Metarhizium anisopliae (MA) is a naturally occurring fungus and one of Hawaii’s most effective biological tools for controlling Coconut Rhinoceros Beetle (CRB). Used in organic gardening, agriculture, and landscaping, MA targets CRB but does not harm people, pets, or beneficial wildlife.​

Why Use MA?

Metarhizium is a natural enemy of CRB, keeping beetle numbers balanced in healthy soil. Modern landscaping and mulch use have reduced natural populations of this fungus—so reintroducing MA is key to biological control. Hawaii studies show that MA kills both CRB larvae and adults in 3–10 days after exposure.​

Where to Apply MA

Most CRB spend their lives breeding in mulch, compost, and decaying vegetation. For best results, apply MA directly to these breeding sites. While MA can be used on tree trunks, it is less effective there as it thrives in moist, decomposing material.dlnr.hawaii+1​

How MA Works

• MA spores land on a beetle’s body and germinate in mulch or soil.

• The fungus grows inside the insect, producing natural toxins.

• CRB die and new spores erupt from their bodies, ready to infect others, repeating the cycle for weeks or months in cool, damp areas.​

Benefits

• Certified organic formulations available (check the product label)

• Safe for humans, pets, pollinators, and earthworms​

• Self-sustains in the right, moist environment

For best long-term results, use MA alongside proper mulch management, sanitation, and trapping—the foundation of integrated CRB pest management in Hawaii.crbhawaii+2​

For more details about MA products and application guidelines, contact 808beetlebusters