- Although one of the most abundant wasp species in Europe and Asia, the paper wasp wasn’t recorded in North America before 1981.
- There are 22 species of paper wasps in North America and nearly 700 worldwide, most of them living in tropical climates.
- Paper wasps are not aggressive insects – they may sting humans and pets only when their nest is threatened or disturbed.
- 90 percent of the entire venom sac content is delivered within 20 seconds.
- Paper wasps have highly specialized face-learning abilities similar to humans, being able to recognize nest mates by variations in their facial markings.
The average size of the paper wasp is 2 cm (0.75 in). They have a small head, medium length antennae, and medium-sized eyes. They are slender with very narrow waists and two pairs of brown wings, with the first pair longer. Their body is reddish brown to black with yellow/orange bands, which is why they are commonly confused with hornets and even honey bees. The legs are slender and long and hang down during flight. Only females are equipped with a stinger that is not barbed, allowing for repeated stinging.
Generally, differentiating between wasps and honey bees can be done by observing the lack of hair on wasps’ bodies and their visibly thinner, more slender bodies. It is, however, more challenging to make a distinction between paper wasps, yellow jackets, and bald-faced hornets, because they all share certain physical and behavioral features: all have narrow wings which are folded along their bodies while resting, they all build nests out of recycled wood fibers, and they deliver painful stings. Although similar in color and shape to yellow jackets in particular, paper wasps’ bodies are slimmer, more elongated, and keep their legs hanging down during flight.
Diet, Behavior & Habits
Compared to other wasp species, paper wasps have a more primitive social organization. The nests, built from plant and wood fibers chewed and mixed with saliva, are suspended from a single stalk and shaped like an umbrella. They are generally formed from single-layer paper cones, have no exterior covering, and hold average-sized populations. Preferred nesting sites include protected and isolated parts of buildings where food is produced or processed – food factories, food stores, restaurants, kitchens, etc. – putting humans in high risk of stings (although less aggressive than other species in their family).
Colonies are founded in early April, soon after mated females (queens) emerge from the secluded places where they hibernate all winter long (piles of wood, holes, vegetation, etc.). One queen (in most temperate species of paper wasps) or several – if there isn’t a dominant egg layer - start building the nest and laying eggs, producing next season’s males and queens. Halfway through the season, the colony will reach about 200 worker wasps: the first generation will be sterile and smaller while the next will be fertile. At the end of the summer, the foundress, reproductive males, and workers die while the new queens go outside to mate. They then enter hibernation and begin the life cycle anew.
Some queens that fail to dominate their workers and maintain control through aggressive dominance may join other queens with established nests, recognizing their authority and becoming workers. The wasps that do this are called “joiners” and, although they initially submit to the founding queen’s authority, they are waiting for a chance to take over control of the nest – a behavior known as usurpation. There are cases when usurpers become queens and founding queens become workers, but these are rare.
Unlike honey bees, paper wasps don’t store nectar in their nests or produce honey. They, as well as their relatives, the yellow jacket and the bald-faced hornet, feed primarily as predators on parasites and insects, especially throughout the warm season. Caterpillars, spiders, flies, grasshoppers, beetles, and other soft-bodied insects are usually paper wasps’ power foods, which are chewed and fed to developing larvae back at the nest. As summer progresses and insects are no longer available, paper wasps turn into scavengers, starting a diet based mostly on carbohydrates, starches, and protein, which brings them in dangerous contact with humans. They prey on picnic meals, overripe fruit, food scraps, and meat they find either in trash cans or inside homes.
Signs of Infestation
Paper wasps are highly social insects and will build their nests in just about any area of your property, including:
- Inside mailboxes, outdoor light fixtures, or in exterior door chimes
- In bird houses and bird feeders
- In vehicles: fenders, bumpers, under the wheel
- Exterior walls of houses, especially on those covered by vegetation
- Under stones in gardens
- In attics
- In wall voids and crawlspaces
- In limbs of trees and shrubs
- In-between crevices in landscape wood
- On roofs under shingles
- Inside outdoor furniture
- Inside folded umbrellas used outdoors or under tables
Management & Control
: Perhaps the simplest way to remove paper wasp colonies is to attack them during April and May, when the nest is still very small (sometimes it only contains the queen). You can simply use a garden hose to forcefully spray the nest or dislodge early-season nests when the queen is not visible on the comb. Refrain from knocking down or disturb in any way large nests – the sting hazard is high even for those who aren’t allergic to their venom.
You can attempt to trap individual wasps by using home-made or commercial traps, which are usually based on the same principle. Wasps that come inside foraging for food are trapped in containers containing meat, protein, sugary foods, or various chemicals that have the same smell as food. However, in the case of paper wasps, which feed primarily on living insects, regular traps may prove ineffective as they don't respond to the same smells like other wasps. Traps placed around the yard can, however, temporarily reduce the problem.
: Insecticides are very effective in eliminating paper wasp nests, but it is important to spray the nest directly and not apply the toxic substances to garden plants or other sites where the insects are regularly seen foraging for food. Do not treat trees, shrubs, and other landscape plants with insecticides because, while it may temporarily reduce wasp presence, the risk of contamination is high.
Although they go by many retail names, the main wasp-killing substances commonly used are just of two types: pyrethrin and pyrethroids. The first is a natural chemical extracted from chrysanthemum flowers, while the second type are human-synthetized to match the structure of the natural pyrethrin. They have a quick knockdown effect, interfering with the nervous system of the insects and paralyzing them.
Paper wasps are significantly more docile than yellow jackets. They are considered pests throughout Canada, but not because they exhibit an aggressive behavior, but because they build nests on just about any residential property and protected backyard sites, so their encounters with people are frequent. Here are some ways to limit interactions and reduce sting hazards:
- Paper wasps react to vibrations nearby or shadows cast on their nest, so make sure you don’t conduct any lawn mowing or weed trimming near a paper wasp colony
- Dark, moving silhouettes constitute visual disturbances for paper wasps, which may cause them to attack
- They also may be provoked into stinging during their scavenger hunts, when natural food sources are scarce and they have to compete with humans for food
- Wasps may exhibit increased aggressiveness when new queens and drones are emerging from the cells, so make sure to stay out of their way during that time