Damsel Bugs

Many slender-bodied insects, such as thrips and leafhoppers, are garden pests. Damsel bugs are an exception. Damsel bugs are predators. And they are very quick.

​Damsel bug actually refers to most of an entire family of insects (Nabidae). Most damsel bugs are Nabis species.

Damsel bug description

Damsel bugs are true bugs (Hemiptera), which makes them cousin to many of their favorite foods. Whereas the “beak” (rostrum) is used by most true bugs to pierce plant tissues and suck sap, damsel bugs use their beak to inject digestive enzymes into victims. In either case, the beak is usually held under the body when not in use.

Adult damsel bug (Katja Schulz) CC BY 2.0

​Damsel bugs have soft, slender bodies that may be brown, gray, yellowish, reddish brown, or tan. Adults are 3/8- to 1/2-inch long. They have long legs and long antennae, and may be confused with equally beneficial assassin bugs. Like assassin bugs, some damsel bugs can and will bite. They are, after all, predators. Medically speaking, as far as I know, damsel bug bites are harmless.

Damsel bug lifecycle

Young damsel bugs, or nymphs, look a lot like adults, which means they go through an incomplete metamorphosis. They have 5 developmental stages, or instars, before reaching adulthood. This process takes approximately 50 days. Adult females hide eggs by laying them inside plant tissue. Damsel bugs are most active in the Bay Area mid-June through mid-August, but they overwinter in ground cover and winter crops, such as alfalfa and many legumes. Remember, just because you don’t see them doesn’t mean they aren’t there.

Damsel bug prey

Like lady beetles and praying mantis, damsel bugs are generalists. This means they will eat whatever they can hold onto long enough to eat. Very often, those meals are aphids, armyworms, small caterpillars and caterpillar eggs, fleahoppers, leafhoppers, lygus bugs, mites, proba bugs, spider mites, and thrips. (Hooray for damsel bugs!) Of course, they will also eat beneficial big-eyed bugs and minute pirate bugs, and occasionally they will even eat plants, but their net result to the garden is still very positive.

In one study, it was estimated that a single adult damsel bug eats 42 moth larvae, 24 lygus bug nymphs, or 5 aphids every day. The same study estimated that a peak population of damsel bugs (283,000 bugs per acre) could consumer 12 million moth larvae, 6 million lygus bug nymphs, 1 million aphids, or some combination of those and other prey, every 24 hours. That’s some significant garden protection!

If you keep a hand lens in your pocket, you may be able to see a damsel bug up close one day.