In our potato trials, we’ve been keeping track of the many natural enemies that attack the Colorado potato beetle (CPB). From lady beetles to hover flies, predatory stink bugs, and even solitary wasps — each plays a role in suppressing CPB populations. Here’s a closer look at some of our most frequent (and fascinating) field allies.
Spotted Pink Lady Beetle (Coleomegilla maculata)
Widespread across North America.
Life cycle: Females can lay 200–1,000 eggs in clusters. Larvae molt four times, pupate, and adults emerge in 3–12 days. Multiple generations per year, with big fall congregations before hibernating in leaf litter or field edges.
Diet: Feeds heavily on aphids, insect eggs (including corn borer and Colorado potato beetle eggs), and small larvae. Also unusual for a lady beetle — up to 50% of its diet can be pollen.
Often found in crop fields, it’s both a voracious predator and a pollen-seeker, making it especially common in flowering intercrops.
Adult
Aphids & CPB eggs — and pollen.
Where
Common in flowering intercrops.
Seven-Spotted Lady Beetle (Coccinella septempunctata)
Seven‑spot ladybird (*Coccinella septempunctata*): widespread in Europe, Asia, and North Africa; introduced for biocontrol and now common across much of temperate North America.
Life cycle: Typically 1–2 generations per year (univoltine to bivoltine depending on climate). Eggs → 4 larval instars → pupa → adult. Adults form overwintering aggregations in leaf litter, under bark, rocks, and buildings; spring dispersal follows aphid flushes.
Diet: Primarily aphids; also thrips, whiteflies, psyllids, leafhopper nymphs, and soft beetle/butterfly larvae. Adults and larvae will supplement with pollen and nectar, and may cannibalize eggs or pupae when prey is scarce.
Defense & signals: Red elytra with seven black spots advertise toxicity (alkaloid-based). When threatened, adults “reflex bleed,” exuding bitter, orange hemolymph from the leg joints.
Ecology & notes: Broad habitat tolerance—meadows, crops, gardens, forest edges—wherever aphids abound. Widely released for biological control; in some regions it displaces native lady beetles. It’s also the national insect of Finland.
Adult
Broad habitat.
Native range
Europe—established in the U.S. in 1973.
Lady beetle
The official state insect in five different states
Harlequin Lady Beetle (Harmonia axyridis)
Originally from Asia, introduced to North America and Europe for aphid and scale control. Now one of the world’s most invasive insects.
Life cycle: Females lay clusters of eggs; larvae pass through five stages before pupating. Adults overwinter in large aggregations (often inside houses). Multiple generations per year.
Diet: Highly generalist — devours aphids, scales, mites, insect eggs, even other lady beetles.
Comes in a huge range of colors and spot patterns (“Halloween beetle” in the U.S.). Effective in pest control, but outcompetes and sometimes eats native species.
Color form
Orange/red with variable spots.
Pattern range
From spotless to many spots.
Generalist
Strong biocontrol… competing with native species.
Overwintering
Aggregates in buildings.
Hover Fly (Family Syrphidae)
Many species are native to North America, though some cosmopolitan species are found worldwide. They are common visitors in crop fields, meadows, and gardens.
Life cycle: Adult females lay eggs near aphid colonies or other soft-bodied prey. The tiny larvae hatch and immediately begin hunting. Syrphid larvae are legless, slug-like maggots that feed voraciously for 1–3 weeks before pupating in the soil or on plant stems. Depending on the species, there can be several generations per year.
Diet & role: Adults feed on nectar and pollen (great pollinators). Larvae are predators of aphids, thrips, and other soft-bodied pests. A single larva can consume hundreds of aphids.
Behavior: Adults hover in place, often mistaken for small bees or wasps, but they lack a stinger and are harmless to humans.
In potatoes, syrphid larvae quietly team up with lady beetles and lacewings to keep aphids in check.
Pollinator + Predator
Adults on flowers; larvae eat aphids.
Spined Soldier Bug (Podisus maculiventris)
The most common predatory stink bug in North America.
Life cycle: Eggs hatch in about a week; nymphs molt through several stages before becoming spined-shouldered adults. They can live 1–4 months and persist year-round in warmer regions.
Diet & role: Both nymphs and adults are fierce predators, feeding on caterpillars and beetle larvae — including the Colorado potato beetle. They’re also sold commercially as a biological control agent.
Unlike many “stink bugs,” this one is a crop ally — its long beak pierces prey insects rather than plants.
Learn more in my full post on the spined soldier bug.
Crop Ally
Targets CPB larvae & caterpillars.
Mason Wasp (Euodynerus sp.)
Euodynerus species are widely distributed across North America.
Life cycle: Solitary wasps. Females build small mud or cavity nests, then hunt soft-bodied larvae (like caterpillars and beetle grubs). Prey are stung, paralyzed, and packed into brood cells, each sealed with a single egg. Larvae develop by consuming the stored prey, pupate, and emerge as adults the following season. Adults are most active in summer, visiting flowers for nectar while hunting in nearby crops and gardens.
Diet & role: Adults feed on nectar and sometimes honeydew, but their larvae depend entirely on paralyzed insects. In potato fields, they’re often seen preying on Colorado potato beetle larvae.
Behavior: Unlike social wasps, mason wasps don’t form colonies. Each female provisions her own nest. They’re not aggressive toward people unless handled.
Control pests and pollinate while foraging.
