The Most Common Bugs in California That Bite or Sting (And How to Avoid Them)

California’s diverse ecosystems are home to many different bugs that can bite or sting. While most bug bites are harmless, some can cause painful reactions or spread disease. As a California resident, it’s helpful to know which bugs you need to watch out for when spending time outdoors.

In this article we’ll cover the most common bugs throughout California that bite or sting the symptoms they cause, and tips to prevent getting bitten or stung.

Mosquitoes

Mosquitoes are likely the most notorious and widespread bugs in California that bite. There are over 20 different species of mosquitoes in the state. Most are primarily nuisance biters but some can transmit diseases like West Nile virus.

Female mosquitoes are the ones that bite. They use the blood meal to develop their eggs. Mosquitoes are most active at dawn and dusk but can bite anytime.

Symptoms: Itchy, red bumps on the skin. Mosquito bites can sometimes swell up big and become hot to the touch. Serious allergic reactions are rare.

Prevention Use EPA-registered insect repellents like DEET, picaridin or oil of lemon eucalyptus on exposed skin. Wear loose, long sleeve shirts and pants outdoors Eliminate standing water sources around your yard where mosquitoes breed

Frequency: Very common throughout California. Most active May through October.

Yellowjackets

Yellowjackets are a type of ground-nesting wasp found throughout California. They have dotted black and yellow patterns on their bodies. Yellowjackets become very aggressive when defending their nests and can sting repeatedly.

Symptoms: Extremely painful stings with swelling and redness. Potential allergic reaction with hives, wheezing, and low blood pressure.

Prevention: Avoid areas where you see lots of yellowjackets flying around. Don’t swat at them. Keep food and drinks covered when eating outdoors. Treat nests on your property with caution and hire a professional if needed.

Frequency: Common in warmer months, especially around food and trash receptacles.

Black Widow Spiders

The Western black widow spider has a infamous dark black body with a red hourglass shape on its underside. Black widows are common throughout California and like to build their webs in sheltered spots like woodpiles, underneath decks, and in garages.

Symptoms: The venom from a black widow bite can cause muscle cramps, nausea, and sweating. In rare cases it leads to dangerous neurological effects.

Prevention: Carefully inspect areas before sticking hands in dark corners or crevices. Wear gloves when working outdoors. Shake out clothing, towels, and shoes before use. Keep spider populations down by removing clutter.

Frequency: Western black widows are found year-round in most parts of California.

Fleas

California has a number of different flea species that infest homes and bite pets and humans. Fleas thrive in warm climates. Young fleas are tiny and can be hard to spot, but adult fleas are visible to the naked eye.

Symptoms: Small red itchy bumps, often around the ankles and legs. Scratching flea bites can lead to infection. Some people may have allergic reactions with hives or rashes.

Prevention: Use flea control products on your pets. Vacuum and wash bedding frequently. Use insect growth regulators indoors. Treat your yard to control fleas in vegetation and dirt.

Frequency: Fleas are found year-round but most prevalent in summer and fall. Common in homes with pets.

Ticks

California is home to several tick species that bite humans including the Western black-legged tick, American dog tick and Brown dog tick. Ticks cling to vegetation and latch onto passing hosts. They prefer shaded, grassy habitats.

Symptoms: Bites are often painless but may turn into large rashes. Ticks can transmit diseases like Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever.

Prevention: Perform tick checks after being outdoors. Wear EPA-registered repellent. Wear light colored clothing and tuck pants into socks. Keep grass mowed and remove brush or leaf litter where ticks live.

Frequency: Most active spring through summer but can be found year-round. More common in rural areas.

Bed Bugs

While not insects, bed bugs are a notorious pest in California that feeds on human blood. Bed bugs are wingless, flat, oval-shaped bugs around the size of an apple seed. They hide in cracks and crevices in bedrooms.

Symptoms: Clusters of small itchy red bumps that may resemble a rash. Bites often appear in a line.

Prevention: Thoroughly inspect for signs of bed bugs when staying in hotels. Isolate and launder infested items immediately upon returning home. Reduce clutter around the home and caulk cracks in walls.

Frequency: Bed bugs are a year-round issue, especially in larger cities and low-income housing.

Kissing Bugs

Also called assassin bugs, there are several species of kissing bugs in California that can bite humans. These bugs get their name because they like to bite around the mouth or eyes. Kissing bugs are primarily an outdoor pest.

Symptoms: Painful swollen bite marks, usually around the face. In rare cases, kissing bugs can transmit Chagas disease.

Prevention: Seal cracks around windows and doors to prevent insects entering homes. Install screens on windows and doors. Avoid sleeping outdoors without protection.

Frequency: More common in rural areas of Southern California. Mostly active spring through fall.

Bee and Wasp Stings

Bees, hornets, yellow jackets, and wasps all inhabit California and can deliver painful stings if disturbed. Africanized “killer” bees are also found in Southern California and are extremely aggressive when provoked.

Symptoms: Instant, sharp pain. Redness, swelling, and itching at the sting site. Potential life-threatening allergic reaction in those hypersensitive to the venom.

Prevention: Avoid areas where you see lots of bees or wasps flying about, especially around nests. Stay calm and still if bees or wasps land on you. Have an epinephrine pen if you have a known allergy.

Frequency: Most bee and wasp species are only active in warmer months, but some like yellow jackets can be found year-round in mild climates.

Chiggers

Chiggers are tiny mites that are common in grassy, overgrown areas. The larvae attach to the skin and inject enzymes that digest skin cells, causing irritation. They prefer to bite thinner skin on ankles, waistline, and groin.

Symptoms: Intensely itchy red welts on skin that appears days after being bitten. Bites may occur in clusters or lines.

Prevention: Avoid walking through overgrown brush and tall grass. Wear protective clothing that covers exposed skin. Apply DEET or permethrin repellent. Shower immediately after coming indoors.

Frequency: Most active May through September. More common in rural areas.

Ants

California is home to many ant species, some of which will bite or sting humans. Red imported fire ants and harvester ants have painful stings similar to wasps and bees. Black ants and Argentine ants will bite but don’t typically sting.

Symptoms: Red imported fire ant stings cause a burning sensation and pustules that can last up to 10 days. Black ant and Argentine ant bites cause mild localized itching and swelling.

Prevention: Wear closed toe shoes outdoors and gloves when gardening. Watch where you put your hands and feet. Treat ant mounds on your property with boiling water or ant baits.

Frequency: Most ant species are active in warmer months when ground temperatures rise. Red imported fire ants common in Southern California.

No-See-Ums

No-see-ums are tiny biting flies, barely visible to the naked eye. They inflict painful bites and prefer warm, moist environments near water and vegetation. No-see-ums are most active at dawn and dusk.

Symptoms: Cluster of small, red, intensely itchy bumps on exposed skin. Bites appear shortly after being bitten.

Prevention: Avoid being outside at dawn and dusk when no-see-ums are most active. Wear protective clothing and use DEET or permethrin. Fix any sources of standing water in your yard.

Frequency: No-see-ums are seasonal, most prevalent May through September. More common near lakes, rivers, and the coast.

Scorpions

California is home to about 7 different scorpion species. The California common scorpion and Arizona bark scorpion are two venomous types found throughout the state. Their stings are painful but rarely life-threatening.

Symptoms: Instant severe pain, numbness, tingling, and swelling. Muscle twitching near the sting.

Prevention: Wear gloves and closed toe shoes when working outdoors. Check gloves, shoes, and clothing before using. Seal cracks in foundations and install weather stripping around doors.

Frequency: Scorpions are most active March through November when nighttime temperatures are above 70°F. More common in Southern California.

Brown Recluse Spiders

While not endemic, brown recluse spiders occasionally find their way to California via shipping containers and vehicles. Their bites can cause severe skin lesions in some cases. Brown recluse spiders have long legs and a distinctive violin-shaped marking on their bodies.

Symptoms: Mild stinging followed by intense pain, itching, redness and blistering starting several hours later. Healing can take 6-8 weeks.

Prevention: Carefully inspect clothing, shoes, and other items when stored in garages, sheds, and attics where recluse spiders may hide. Seal boxes and use sticky traps when moving interstate.

Frequency: Uncommon, but occasionally found in Southern California.

Wheel Bugs

Wheel bugs are large predatory insects named after their distinctive wheel-like cog mid-section. They have piercing, sucking mouthparts that inflict a very painful bite. Wheel bugs feed on garden pests but will bite defensively if picked up or disturbed.

Symptoms: Instant, intense piercing pain. Bite turns red, swollen, may feel warm/numb. Pain and swelling fades after 1-2 days.

Prevention: Leave wheel bugs alone and do not touch. Teach children not to pick up insects they don’t recognize. Keep wheel bugs out of play areas. Remove debris/firewood piles where they live.

Frequency: More common in gardens and natural areas. Most active late spring through early fall.

How to Treat Insect Bites and Stings

Most mild insect bites and stings can be treated at home:

• Clean the bite area with soap and water to remove any remaining venom/saliva from the insect.

• Apply a cold pack wrapped in cloth to reduce swelling, pain, and itching.

• Use over-the-counter hydrocortisone cream or calamine lotion to ease itching.

• Take antihistamines containing diphenhydramine to help reduce swelling, itchiness or rashes.

• Monitor for any signs of infection like increasing warmth, redness, pus, or swollen lymph nodes.

See a doctor for severe reactions, multiple stings, or stings inside the mouth or nose that may block airways. Those with known venom allergies should carry an epinephrine auto injector and use immediately if stung.

With proper precautions, most insect bites and stings can be avoided. Be vigilant when spending time outdoors, especially during warmer months when insects are most active. Identifying and removing nests or attractants like standing water from your yard can also reduce encounters with stinging and biting bugs in California.