Bug of the Month Damsel Bug (Nabis alternatus)
The Damsel Bug is probably one of the most common predators, and therefore beneficial insects, we find in all crops. It can be abundant in fields and is a generalist predator that will eat whatever it can find and subdue
“Both adults and nymphs are fast, aggressive predators. They grasp their prey and pierce the body, injecting toxic saliva that paralyzes prey and digests body contents they then suck up,” from page 120, Agriculture & Agri-Food Canada Field Guide
Damsel bugs feed on many types of insects. They are predators of aphids, moth eggs, and small caterpillars, including corn earworm, European corn borer, imported cabbageworm and some armyworms. Other prey may include leafhoppers, small sawfly larvae, mites, tarnished plant bug nymphs, and asparagus beetle and Colorado potato beetle eggs and nymphs. They typically eat one egg or aphid per day when small and as many as 1-2 dozen eggs or other prey as later instars and adults. Although they can survive for up to two weeks without food, if no other prey is available, they will turn to cannibalism. They use their thickened raptorial front legs that are lined with spines to catch and hold prey, then suck out the body contents with their piercing mouthparts
Student Arash Kheirodin used DNA gut content analysis to show that along with lady bird beetles it is one of the top predators that consumed cereal leaf beetle larvae in wheat fields of southern Alberta
Members of the genus Nabis are the most abundant damsel bugs found in crops and gardens. The most common species in North America is N. americoferus. Which has one to two generations per year and overwinter as an adult. The females deposit their tiny eggs in plant stems or other tissue and the immatures (nymphs) go through five instars before becoming adults.
Damsel bugs are commonly found in home gardens, where they prefer to take shelter in low growing grasses and ground covers. Maintaining such environments will encourage these predators. So, keep your eyes peeled for these “Damsels that cause Distress” in your backyard.
