With summer comes those dreaded yellow jackets. The yellow and black banded insects are the top stinging pest in Colorado. Their ability to sting multiple times, paired with their aggressively defensive nature, makes them one of those insects that no one wants around. Understanding them may help us to avoid these troublesome wasps and enjoy a safer, sting-free season.
The term “yellow jacket” refers to a number of species of wasps in the genera Vespula and Dolichovespula (family Vespidae). Included in this group of ground-nesting species are the Western yellow jacket, V. pensylvanica, which is the most commonly encountered species in El Paso County. They are sometimes called “meat bees” because of their voracious appetite for protein.
Being able to identify the difference between a bee and a wasp is important. For general identification the honeybee, bumblebee and leaf cutter bees are hairy and stout-bodied with muted colors of black, brown, yellow, orange and gray and commonly have pollen on their bodies. Hornets, yellow jackets and paper wasps are not hairy, have elongated bodies and brighter coloring of black, yellow, orange and creamy white.
Bees and wasps are usually nonaggressive unless trapped (stepped on) or their nest is disturbed. Solitary bees as well as honeybees have no interest in human food. On the other hand, yellow jackets are scavengers and thrive on sugary drinks, sweet food and meat. Yellow jackets typically nest underground using existing hollows. Nests can be found in dark, enclosed areas, such as crawl spaces, under low-lying decks or in garden sheds. Honeybees live in an above-ground hive or in a tree. Solitary bees are seldom noticed. According to Colorado State University, 90% of the bees in Colorado are solitary types including leafcutter, digger, sweat and carpenter bees. They nest in hollow twigs or any other opening about the diameter of a pencil. They also utilize cracks and hollow tubes of patio furniture.
Western yellow jackets are attracted to the chemical hepytl butyrate, which makes them susceptible to early control with a wasp trap. These reusable traps can be purchased at most local hardware and garden stores. No other bees or wasps are attracted to the yellow jacket- baited wasp trap. This trap should be placed in early spring, when the queen is foraging for nesting material and protein. Store-bought traps require a refill of the chemical attractant every four to 10 weeks. They are relatively inexpensive (around $10 for the trap and $4 for the refill attractant) and do a decent job. There are many do-it-yourself traps made from plastic soda/water bottles that produce good results. Peter Landolt, USDA entomologist in Wapato, Wash., studies the chemical ecology of insects and has developed do-it-yourself traps to attract food-eating social wasps. The key is first determining the problem wasp species, and then selecting an appropriate trap. His research has found that yellow jackets are definitely attracted to meat baits.
The one redeeming quality these wasps have is that they are fearsome predators and work diligently to control unwanted garden insects.
The El Paso County Extension is operating remotely due to COVID-19. You can submit gardening questions by email at email@example.com.