Natural Pest Management: Hawaii's Biocontrol Successes Part 3: Plants to Attract Beneficial Insects

Integrating conservation biological control into Hawaiian agroecosystems relies on strategically manipulating habitats to attract key natural enemies like lady beetles, hoverflies, and parasitic wasps. In Hawaiʻi’s tropical climate, monoculture environments often lack the continuous resources these beneficial insects require. To retain them, farmers must bridge the gap between native or non-crop habitats and production fields by planting specific floral resources (incentive strips) that provide essential nectar, pollen, and alternative prey.

Attracting Lady Beetles, Hoverflies, and Parasitic Wasps

Lady beetles and hoverflies are highly attracted to accessible, shallow flowers. Planting flowering insectary covers such as buckwheat (Fagopyrum esculentum) or sunn hemp (Crotalaria juncea) delivers the quick pollen punch needed to stimulate lady beetle reproduction and fuels adult hoverflies, whose voracious larvae consume aphids and thrips . Similarly, tiny parasitic wasps thrive when provided micro-floral structures from plants like sweet alyssum or native Hawaiian ʻilima (Sida fallax), which offer easily reachable nectar reservoirs. By establishing these diverse botanical refugia adjacent to crops, farmers mimic natural Hawaiian forest edges. This structural diversity ensures that when pest populations spike, a permanent, resident army of natural predators is already acclimated and ready to spill over into the agroecosystem.

• Buckwheat: A fantastic fast-growing cover crop that unlocks soil phosphorus while producing tiny white flowers that hoverflies and parasitic wasps love.

• Cilantro and Dill: When allowed to bolt and flower, these herbs act as magnets for lady beetles and small predatory wasps.

  
  

Attracting Minute Pirate Bugs

Minute pirate bugs (Orius species) serve as highly effective generalist predators within Hawaiian agroecosystems. These tiny, highly mobile true bugs are voracious consumers of soft-bodied agricultural pests, actively preying on thrips, spider mites, aphids, and the delicate eggs of corn earworms. Both the nymphal and adult stages utilize a specialized piercing mouthpart called a rostrum to drain the bodily fluids of their prey, rendering them an indispensable asset for local integrated pest management (IPM).

To successfully attract and preserve robust communities of minute pirate bugs, organic growers must strategically incorporate diverse floral habits. Because Orius species depend heavily on pollen and plant juices as a secondary food reservoir when active prey populations drop, they naturally gravitate toward spring and summer flowering shrubs, weeds, and agricultural cover crops. In Hawaiʻi, establishing insectary patches or windbreaks of rapid-flowering buckwheat (Fagopyrum esculentum) provides an excellent habitat, allowing the predators ample time to complete subsequent generational breeding cycles. Furthermore, intercropping with sweet corn benefits these predators, as they frequently shelter in protective corn silks. By reducing broad-spectrum chemical sprays and linking diverse field margins to production rows, farmers establish a stable ecological infrastructure that sustains these beneficial insects year-round.

• Marigolds and Cosmos: These low-cost, easy-to-grow flowers provide excellent habitat and pollen for minute pirate bugs when prey is scarce.

  
  

Attracting Trichogramma Wasps

These microscopic wasps are incredible allies, parasitizing the eggs of many destructive caterpillars.

• Sunn Hemp and Cowpea: Both of these are excellent leguminous green manures. They fix nitrogen in your soil while their foliage and flowers attract and sustain Trichogramma wasps.

  
  

By carefully selecting your insectary plants, you can build a resilient, self-regulating ecosystem on your farm. This tailored approach reduces your reliance on external inputs, builds soil health, and keeps your organic operation thriving year after year. Join our community forums to share your own experiences with cover crops and biocontrols, and discover how other women are transforming their farms!

FMI:

Hamasaki, R. T., Valenzuela, H. R., & Shimabuku, R. S. (2011). Silverleaf Whitefly Management in Hawaii Agricultural Systems. University of Hawaiʻi at Mānoa, College of Tropical Agriculture and Human Resources.https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-32.pdf

Hooks, C. R. R., Wang, K. H., Ploeg, A., & McSorley, R. (2011). Using marigold and sunn hemp cover crops to manage pests. College of Tropical Agriculture and Human Resources Extension Publication, SCM-31.https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-31.pdf

Messing, R. H., & Wright, M. G. (2006). Biological control of aphid pests in Hawaii. Proceedings of the Hawaiian Entomological Society, 38, 1–13.http://hdl.handle.net/10125/112

Vargas, R. I., Leblanc, L., Harris, E. J., & Manoukis, N. C. (2012). Regional Suppression of Bactrocera Fruit Flies in the Pacific through Biological Control. Insects, 3(3), 727–742.https://doi.org/10.3390/insects3030727

Wright, M. G. (2007). Scale insects and their natural enemies in Hawaii agricultural systems. University of Hawaiʻi at Mānoa, College of Tropical Agriculture and Human Resources.https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-27.pdf