With unseasonably warm weather hitting the Bay Area over the past week, flowers have been blooming and insects (and spiders) have been active. It's almost as if spring was here! Last Thursday lepidopterist Liam O'Brien and I took a sojurn to San Jose's Alum Rock Park to see if any early-emerging butterflies were taking advantage of the warmth and were not disappointed.

The early blooming flowers non-natives like Mustard and Bermuda Buttercup, but the plethora of beckoning blossoms attracted a wonderful group of insects. With his experienced lepidopterist eyes, Liam spotted a stunning Mourning Cloak butterfly patrolling a glade right after we left the car. Sara Orangetip butterflies, who rarely land this early in the season, made many appearances along the canyon walls as well.

A Goldenrod Crab Spider with its Mylitta Crescent lunch. Photo by Tony Iwane.

As we approached a stand of mustard flowers, Liam pointed out a Mylitta Crescent butterfly that was hanging at an odd angle from one of the plants. "That one's gotta be a Crab Spider meal," he told me. And yup, when we got a better look the butterfly was indeed being held in the chelicerae of a Goldenrod Crab Spider.

Crab Spiders are ambush predators and don't spin webs. Instead, many set up shop on a flower and lie in wait for pollinators, who are pretty much bound to show up at some point. I always stop and take a look at flowers when I'm on a hike - each one is a world unto itself.

Our target species of the day was the stunning Sonoran Blue butterfly, which has been called the most beautiful small butterfly in the US. Alum Rock Park is one of the few places one can find this insect in the Bay Area, and we got lucky, seeing several males and females patrolling the talus along the cliff sides. The males of this species have an electric blue coloration on their wings. The females, while less vibrant, have orange spots on both pairs of wings, as opposed the males, who have orange only the forewings. This was the first time I'd seen this butterfly and I was not disappointed.

A male Sonoran Blue butterfly. Photo by Tony Iwane.

Liam has offered to lead a butterfly walk for CCNH in Alum Rock Park on Saturday, March 5th from 11am - 2pm. He is as entertaining and inspirational a naturalist as you'll com across, and has been honored as a Local Hero by Bay Nature Magazine for his work in Environmental Education. This is a great opportunity to learn about butterflies in a fantastic setting, and we'll be looking for more Sonoran Blues! Click here for more information about the program. Space is limited so sign up today!