Damsel bugs
Yes. Damsel bugs are predatory true bugs, about 1/6 to 1/2 in (4–13 mm) long, slender and usually tan, grey or brown, with a narrow head, bulging eyes and long antennae. They catch prey in spiny, thickened front legs and suck it dry. Adults and nymphs eat aphids, moth eggs, small caterpillars such as corn earworm and imported cabbageworm, leafhoppers, mites, thrips and plant bug nymphs. Nabis species are among the commonest predators in row crops in the southeastern US, but damsel bugs are not sold for release. Keeping them means leaving some low, grassy cover where they shelter.
At a glance
- Kind
- Wild — attracted, not bought
- Adult
- 1/6–1/2 in (4–13 mm); slender, tan to grey
- Eats
- 1 egg or aphid a day when small; up to about 2 dozen as adults
- Egg to adult
- 1–2 months in warm weather
- Nymphs
- 5 instars, 3–4 weeks in all
- Generations
- 1–2 a year in Wisconsin, 2 or more elsewhere; most winter as adults
How it works
Damsel bugs are true bugs in the family Nabidae. The genus Nabis holds the most abundant species, and N. americoferus is the commonest in North America. They take their name from the way they hold their front legs up, as if lifting a skirt hem to curtsey. The front legs are thickened and lined with spines, and they use them to grab prey before piercing it with the beak and sucking out the contents.
Adults and nymphs both hunt. Small nymphs eat about one moth egg or aphid a day, and later instars and adults as many as one to two dozen eggs or other prey. They can go two weeks without food, and when prey runs out they turn cannibal. Females insert their eggs into the stems of low-growing plants. A pale damsel bug female can lay up to 200. The eggs hatch in about 8 days in summer, and the nymphs, which look like small wingless adults, pass through five instars over three to four weeks.
Most winter as adults, a few as late-instar nymphs, in weeds, ground cover or other protected places. In Wisconsin the common species have one or two generations a year; UC IPM gives two or more, and the pale damsel bug has several a year in the Southeast. UC IPM notes they also feed harmlessly on plant material.
What it is confused with
Damsel bugs share gardens with pests they resemble, and with other predators. The front legs and the wing tips separate them.
- Also goodAssassin bugs — Wisconsin Extension says damsel bugs resemble small, smooth-looking assassin bugs. Both are predators, so either can be left alone.
- PestTarnished plant bug and other plant bugs — UC IPM's tell is at the wing tips: a damsel bug has multiple elongated cells, or translucent areas between veins, round the outer edge of the front wing; plant bugs have only one or two closed cells.
- Also goodMinute pirate bugs — Also predators. UC IPM's tell: a minute pirate bug has no visible veins near the tip of the front wing.
- Also goodPraying mantises — UF/IFAS says that at first glance a damsel bug looks like a cross between a mantis and an assassin bug, because of the raised, grasping front legs. All three are predators.
How to keep it around
Damsel bugs live low in the vegetation. Wisconsin Extension and UF/IFAS suggest keeping the cover they shelter in:
- Low-growing grasses and ground covers left in and around the garden, where damsel bugs shelter
- Weeds and ground cover left in place over winter, where the adults overwinter
- Some prey left alive: damsel bugs survive only about two weeks without food and turn cannibal when it runs out
- Count before you spray, so a planting is not treated for a few aphids and the predators with them
When to choose something else
Damsel bugs give free background predation, but Wisconsin Extension notes their effect on pest damage in home gardens is not known. Look elsewhere when:
- Caterpillars are already feeding on brassicas or tomatoes — use Bacillus thuringiensis (Bt kurstaki) on young larvae
- Corn earworm eggs are being laid on silks or tomatoes — Trichogramma wasps parasitise the eggs and can be bought for release
- Thrips are building under glass — use a bought predator such as Orius insidiosus
Damsel bugs by target
What it eats and when it turns up differ by pest. Each page below is the picture for one target.