By Kaitlin Campbell, Rita Hagevik, and Kathy Cabe Trundle | October 1, 2024

Creating Sustainable School and Home Gardens: Beneficial Biological Control Insects

A ladybug with black spots on its red shell is crawling on a green leaf.

Insects and arthropods, some of the most abundant residents in school and home gardens, play many significant roles as predators, herbivores, detritivores, and parasites. Predators are particularly important in the garden because they help keep the “bad,” herbivorous, pest insects under control.

Biocontrol is long-lasting, inexpensive, and supports pollinators and the natural enemies that live in your garden.

Biological control (biocontrol) occurs when humans use living organisms (typically predators, pathogens, or parasites) to control pest populations. While any predator might be able to eat herbivores, many generalist predators will eat anything, good or bad, which can include other predators and pollinators! Specialist predators are specifically adapted to target key pests (caterpillars, aphids, slugs) and typically do not harm other beneficial insects like pollinators.

On small scales, like school and home gardens, encouraging biological control agents can be highly effective, reducing the need for insecticides that harm the environment, humans, and beneficial insects. For example, you might notice some aphids harming a plant and purchase a specialized, natural predator like green lacewings or lady beetles to control the aphids rather than spraying the plant with a toxic insecticide.

You can encourage beneficial insects by providing alternative food (nectar and pollen plants) throughout the year, overwintering habitat (shelter, shrubs, perennial plants, leaf litter), and avoiding using pesticides. For example, you might plant sunflowers, zinnias, marigolds, and nasturtiums among your garden plants.

Learn More and Explore With Your Own Field Guide

For more information, see the Resources section, with links to learning materials for promoting helpful insect populations. Also see a related Utah State University (USU) Extension fact sheet: Creating Sustainable School and Home Gardens: Welcoming Pollinators. A simple field guide titled Quick Reference Field Guide for Garden Biocontrol Agents follows at the end of this fact sheet. You may want to print the field guide and laminate it for use in your garden! Biocontrol is long-lasting, inexpensive, and supports pollinators and the natural enemies that live in your garden.

Resources

USU Extension Fact Sheets and Websites

Pest Control in School Gardens

Dealing With Garden Pests and Diseases, Kids Gardening
A Guide to Controlling Insects in the School Garden, Louisiana State University Ag Center
Bug 2 School, University of Illinois Urbana-Champaign

Other Resources

Beneficial Insects, Arbico Organics, biocontrol agents seller
Stink Bugs: Telling the Good Ones From the Bad Ones, Ask an Entomologist
Biological Control Information Center, North Carolina State University Extension
Why Provide Habitat for Beneficials? North Carolina State University Extension

Quick Reference Field Guide for Garden Biocontrol Agents

Generalist Biocontrol Agents	Specialist Biocontrol Agents
Spiders (Araneae)	Lady Beetles (Coccinellidae)
8 legs, 2 main body sections. Catch insects by actively hunting, ambushing, or with webs. Wolf spider - Patrick Edwin Moran Jumping Spider - Sarah Siefken	Eat aphids, scale, whiteflies as adults and larvae. Black and red/orange, usually with spots as adults (1/4”); larvae look like spikey little black and orange monsters. Lady Beetle Larva - Patrick Murray Lady Beetle Adult - Seth Ausubel
Praying Mantids (Mantidae)	Big-Eyed Bugs (Geocoridae)
Large, long slender bodies, grasping forelegs for prey capture, and brown, green, triangular head. Ambush and capture prey on vegetation. European Mantis - Charles J. Sharp	Eyes wider than body, triangle on back, small (1/6”). Eat small insects, insect eggs, aphids, and mites. Big-Eyed bug - Julieta Brambila, USDA
Assassin Bugs (Reduviidae)	Lacewings (Chrysopidae, Hemerobiidae)
Wide abdomen, long legs, narrow head with beak-like stabbing mouthpart, and colored brown, green, or gray. Ambush and capture prey on vegetation. Wheel bug - Debbie Roos	Adults green or brown, medium-sized, net-like wings (1/2”-3/4”); larvae look like brownish alligators with big jaws. Larvae eat aphids, and adults eat nectar and pollen. Green Lacewing Larva, The backyard arthropod project Green Lacewing adult
Wasps and Hornets (Vespidae, Sphecidae, Pompylidae, and many more)	Soldier Beetles (Cantharidae)
Large to medium, clear or black wings, slender bodies, narrow waist, typically yellow and black, black, or brown and yellow. Some specialize on caterpillars, spiders, roaches, grasshoppers.	Elongate with soft, leathery wings, usually black and red or yellow/orange. Adults eat pollen and aphids, and larvae eat caterpillars and soil pests. Soldier Beetle
Centipedes (Chilopoda)	Minute Pirate Bugs (Anthocoridae)
Large to medium, long, and many segmented with many legs (2 legs per segment), fast-moving on the ground. Eat soil-dwelling arthropods. Centipede - Robbie Geophilomorpha centipede - Silesianguy, iNaturalist House centipede - Robby Deans	Black and white, extremely small (< 1/16”). Eat thrips, mites, aphids, and tiny caterpillars. Minute Pirate Bug - John Rosenfeld
Robber Flies (Asilidae)	Ground Beetles (Carabidae)
Medium to large fly with clear wings, large eyes, long pointed abdomen, fuzzy head with beard; sometimes mimics bees. Eat anything they can catch; often catch flying insects. Robber fly - Fritz Geller-Grimm Robber fly - Wikimedia	Shiny black (can also be iridescent or with orange legs), fast-moving on the ground, usually medium to large (> 1/2”). Eat soil-dwelling pests (caterpillars, beetle grubs, slugs, snails, cutworms) as adults and larvae. Ground Beetle - Chris Joll
Ants (Formicidae)	Hoverflies (Syrphidae)
Small, wingless, black, brown, red, or orange, often forming large colonies. Eat any insects on ground or vegetation and scavenge dead insects; may protect aphids in exchange for sugary secretions. Odorous House Ant with Aphids - Jim Brighton	Adults yellow and black, mimicking bees (1/8”-1/2”); larvae very small, green/yellow, caterpillar-like (~1/8”). Adults pollinate; larvae eat aphids. Larva - Oregon State Universtiy Hoverfly Adult - David Silsbee
Predatory Stink Bugs (Pentatomidae)	Parasitoid Wasps (Braconidae, Ichneumonidae, others)
Shield-shaped with piercing mouthpart. Most stink bugs are herbivores, but predatory stink bugs have thicker piercing mouthparts and single-color antennae; they often have pointy shoulders. Ambush prey on vegetation and flowers. Spined Soldier Bug - Michael R. Stink bug - Judy Gallagher	Diverse—extremely tiny to large, often with long ovipositor (tail) for injecting eggs into host; often long and thin, with black wings. Adults lay eggs in larvae and eggs of various insects, eventually killing them; adults drink nectar. Braconid Parasitoid - NCSU Ichneumon Parasitoid Wasp - Roger Rittmaster