3.1 Stinging and Biting Insects: Bees, Wasps, Hornets, Yellowjackets, and Bed Bugs

Stinging and Biting Insects: Bees, Wasps, Hornets, Yellowjackets, and Bed Bugs

Stinging and biting insects represent a major category of pests for California Structural Pest Control Board Branch 2 licensees. These pests are not only public health hazards due to painful bites and stings, but they can also trigger severe, life-threatening allergic reactions (anaphylaxis) in sensitive individuals. Managing these pests requires a solid understanding of their biology, nesting habits, and the regulatory frameworks governing their control in California.

Yellowjackets (Vespula and Dolichovespula spp.)

Yellowjackets are highly aggressive social wasps. They are easily recognized by their bright yellow and black bands on the abdomen and a distinct, narrow waist (petiole). Unlike honey bees, yellowjackets have smooth stingers, meaning they can sting a victim repeatedly without losing their stinger or dying.

Nesting Habits

Yellowjackets build nests made of paper-like material (chewed wood mixed with saliva). A key identification point for the exam is their nesting location:

1. Subterranean: Many species, such as the Western Yellowjacket (Vespula pensylvanica), nest underground in abandoned rodent burrows or natural soil cavities.
2. Structural Voids: They frequently build nests inside structural wall voids, attics, or crawl spaces, entering through small gaps on the exterior.

Aggressive Behavior and Seasonal Diet Shifts

Yellowjackets exhibit a dramatic shift in feeding behavior that directly affects their aggressiveness:

• Spring and Summer: The colony is focused on rearing larvae, which require high-protein diets. Workers forage for insects, spiders, and carrion. During this phase, they are less aggressive toward humans unless the nest is approached.
• Late Summer and Fall: As queen production ceases and the colony begins to decline, the workers' diet shifts from protein to carbohydrates (sugars). They swarm around trash cans, soda cans, and outdoor dining areas. Hungry and lacking food from the nest, they become extremely aggressive, presenting a major public health nuisance.

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Paper Wasps (Polistes spp.)

Paper wasps are slender with long, dangling legs during flight. They are typically reddish-brown to black with yellow markings.

Nesting and Behavior

Unlike yellowjackets, which enclose their nests in a papery envelope, paper wasps construct open, single-layer paper combs.

• Nest Shape: The nest resembles an upside-down umbrella (often called an umbrella nest) and is suspended by a single pedestal (petiole).
• Locations: These nests are commonly found under eaves, window frames, door frames, or inside utility boxes.
• Behavior: Paper wasps are generally much less aggressive than yellowjackets. They will coexist with humans without stinging unless their nest is directly disturbed or touched.

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Honey Bees (Apis mellifera)

Honey bees are crucial agricultural pollinators. They have hairy, robust bodies with black and amber-brown bands.

Barbed Stingers and Autotomy

Unlike wasps, honey bees have barbed stingers. When a honey bee stings a human or mammal, the barbs anchor the stinger into the skin. As the bee pulls away, the stinger, venom sac, and attached muscles are torn from the bee's abdomen (autotomy), which kills the bee.

• Treatment Tip: The stinger should be scraped off the skin immediately using a fingernail or credit card. Squeezing or pinching the stinger with fingers or tweezers compresses the venom sac, forcing more venom into the victim.

California Regulations and Relocation

Under California law, honey bees are not classified as pests in the same manner as structural pests. Due to their ecological importance, pesticide application to honey bee swarms or hives should be a last resort.

• SPCB Exam Point: Before attempting chemical control, licensees must recommend or coordinate with registered beekeepers to relocate viable hives. Chemical eradication is only acceptable when a hive poses an immediate health threat to humans or animals and relocation is impossible.

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Bed Bugs (Cimex lectularius)

Bed bugs are obligate hematophagous (blood-feeding) ectoparasites that primarily target humans.

Identification

• Appearance: Adults are small (about the size of an apple seed, 4-5 mm), wingless, reddish-brown, oval-shaped, and dorsoventrally flattened (flat from top to bottom). After a blood meal, their body elongates, swells, and turns a brighter red.
• Wings: They possess vestigial wing pads but are completely wingless and cannot fly or jump.

Metamorphosis and Lifecycle

Bed bugs undergo gradual (hemimetabolous) metamorphosis, which consists of three stages: egg, nymph (five distinct instars), and adult.

• Blood Meal Obligation: A nymph must consume a blood meal to successfully molt into the next instar stage.
• Egg Laying: Females can lay 1-5 eggs per day, adhering them to rough surfaces with a glue-like substance.

Habits and Harborages

Bed bugs are nocturnal, feeding on hosts while they sleep. During the day, they hide in dark, sheltered harborages. Because of their flat bodies, they can squeeze into paper-thin cracks.

• Common Harborages: Mattress seams, box springs, headboards, baseboards, electrical outlets, wallpaper seams, and bedside furniture.
• Signs of Infestation: Fecal spotting (dark, reddish-black spots of digested blood), shed skins (exuviae), and sweet, musty odors in heavy infestations.

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Comparison of Stinging and Biting Insects

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SPCB Exam Traps

1. The Stinger Trap: A common exam question asks how to remove a honey bee stinger. The correct answer is always to scrape it off, never squeeze or pull it, as squeezing injects more venom from the attached sac.
2. Metamorphosis Distinction: The exam will test your knowledge of metamorphosis types. Wasps, bees, and flies undergo complete metamorphosis (egg, larva, pupa, adult). Bed bugs, earwigs, and cockroaches undergo gradual metamorphosis (egg, nymph, adult). Do not confuse them.
3. Bed Bug Wings: A frequent trick question asks about bed bug flight patterns. Remember, bed bugs are wingless and cannot fly. They move entirely by crawling or hitchhiking on luggage and clothing.

Real-World Scenario

A technician responds to a call about wasps swarming a backyard patio in late September. The customer wants the eaves sprayed. Upon inspection, the technician finds no nests under the eaves but notices yellowjackets feeding on fallen fruit under an apple tree. The correct course of action is to explain the seasonal carbohydrate shift, recommend sanitation (removing fallen fruit and securing trash lids), and place yellowjacket traps around the perimeter, rather than blindly spraying pesticide on the eaves where no nests exist.