The mild weather typical of Southern California is favorable for outdoor activities, but it also means that allergies and certain pest issues persist throughout the year.

Here is a summary of allergenic plants and pests to watch out for in the Irvine area.

Allergy-related: The most common allergen in Irvine is pollen. From February to May, pollen from olive trees, eucalyptus, cypress, and various grasses is prevalent. Many residents experience symptoms such as itchy eyes, sneezing, and nasal congestion during this time due to the abundance of olive and eucalyptus trees planted for landscaping.

In the fall (August to November), ragweed pollen can further exacerbate allergy symptoms. It is recommended to check the pollen count on AirNow.gov and to limit outdoor activities or wear masks on days with severe symptoms. Antihistamines (Claritin, Zyrtec, Benadryl) and nasal sprays (like Flonase) are readily available at pharmacies.

Pest-related: One pest to be cautious of in Irvine is the black widow spider. They inhabit dark, dry places such as garages, sheds, under trees in gardens, and beneath outdoor furniture.

A bite can cause severe pain and muscle cramps, so it is important to wear gloves and check the surroundings when working outdoors. If bitten by a black widow, seek emergency medical attention immediately. The brown recluse spider is rare in Irvine but not completely absent.

Due to Southern California's dry climate, mosquitoes are much less common than in Korea or the southeastern U.S., but after the rainy season (December to March), populations of the Aedes aegypti mosquito can increase in areas where water collects. This mosquito can transmit Zika, dengue, and chikungunya viruses, prompting warnings from the Orange County Vector Control District (OCMVCD). Removing standing water indoors and outdoors (from plant saucers, bird baths, drains, etc.) is essential for prevention.

Cockroaches can occasionally be found in older apartment complexes, and using professional pest control services is effective when they are discovered. Coyotes have also been spotted at the boundaries of the Irvine eastern natural area and residential neighborhoods, so it is advised not to leave small pets outdoors unattended.