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Wildflower Mount Diablo Russian Thistle Invasive, naturalized Scientific Name: Salsola tragus Family: Amaranthaceae Blooms: October Color: White Annual herb Introduced Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Steven Beatty

Wildflower Mount Diablo Cobweb Thistle, Venus Thistle Scientific Name: Cirsium occidentale Family: Asteraceae (Sunflower Family) Blooms: Apr - Jul Color: Red-Pink Perennial herb Native, endemic to California Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Mike Woodring Terese Dixon

Shrubland Allen's Hummingbird Selasphorus sasin American Goldfinch Spinus tristis American Pipit Anthus rubescens Anna's Hummingbird Calypte anna Bell's Sparrow Artemisiospiza belli Bewick's Wren Thryomanes bewickii Black-throated Gray Warbler Setophaga nigrescens Blue-Gray Gnatcatcher Polioptila caerulea Bushtit Psaltriparus minimus California Quail Callipepla californica California Scrub Jay Aphelocoma californica California Thrasher Toxostoma redivivum California Towhee Melozone crissalis Calliope Hummingbird Selasphorus calliope Chestnut-backed Chickadee Poecile rufescens Chipping Sparrow Spizella passerina Common Poorwill Phalaenoptilus nuttallii Dark-eyed Junco Junco hyemalis Fox Sparrow Passerella iliaca Golden-crowned Sparrow Zonotrichia atricapilla Hermit Thrush Catharus guttatus Horned Lark Eremophila alpestris Hutton's Vireo Vireo huttoni Lazuli Bunting Passerina amoena Lesser Goldfinch Spinus psaltria Loggerhead Shrike Lanius ludovicianus Nashville Warbler Oreothlypis ruficapilla Northern Mockingbird Mimus polyglottos Oak Titmouse Baeolophus inornatus Orange-crowned Warbler Leiothlypis celata Phainopepla Phainopepla nitens Rock Wren Salpinctes obsoletus Ruby-crowned Kinglet Corthylio calendula Rufous Hummingbird Selasphorus rufus Rufous-crowned Sparrow Aimophila ruficeps Savannah Sparrow Passerculus sandwichensis Spotted Towhee Pipilo maculatus Steller's Jay Cyanocitta stelleri Townsend's Warbler Setophaga townsendi Turkey Vulture Carthartes aura Warbling Vireo Vireo gilvus Western Tanager Piranga ludoviciana White-crowned Sparrow Zonotrichia leucophrys Wilson's Warbler Cardellina pusilla Wrentit Chamaea fasciata Yellow Warbler Setophaga petechia Yellow-rumped Warbler Setophaga coronata

Pepsis Tarantula Hawk Has Found Its Prey by Dan Sandri You do not want to get stung by this one! July 5, 2025 A Desert Tarantula (Aphonopelma iodius) sits paralyzed, as a Pepsis Tarantula Hawk looks for a nest burrow. By Dan Sandri After keeping an eye out for years, I finally encountered a Pepsis wasp with its prey item in Mount Diablo State Park: a Desert Tarantula (Aphonopelma iodius )! While most of us “Mount Diablo-philes” have a great love for our local tarantulas, I am also enamored with Tarantula Hawks – those large, magnetic blue-black wasps with the orange wings! By the way, I have not been stung by a Tarantula Hawk, as I very much treat them with the respect they deserve (Pepsis grossa is one of just 3 insect species to have been given a Schmidt Pain Scale rating of 4, the highest pain rating, by University of Arizona Entomologist Dr. Justin O. Schmidt. Yes, he tested the pain levels!). He described the pain by writing that “screaming is satisfying and helps reduce attention to the pain of the sting” – a pain that is “instantaneous, electrifying, excruciating, and totally debilitating.” No thank you! So, I watched with a mixture of sadness and exhilaration as the Tarantula Hawk dragged the already paralyzed spider off a grassy hillside and along the trail ahead of me. I didn’t see the capture. Given that it is early July, it is very likely that the Pepsis wasp (identified by its wing venation) found the tarantula in its burrow and coaxed it out or forced it out by entering the burrow. Alas, there was likely no epic battle, as I don’t think the Tarantula Hawks ever lose. Interesting to me, however, is the fact that, if it is true that the tarantula was in its burrow, the Pepsis wasp didn’t use the tarantula burrow as the nest for its larva that will slowly feed on the still-alive spider. They have been known to use the tarantula burrow or to find their own burrow. It chose to drag the spider along the trail and stopped to check out two pre-existing burrows on the trail, deciding on the second one as the home for its egg-larva-pupa. The larva will feed on the non-vital parts of the tarantula first, grow steadily, before finishing off the spider, pupating, and will likely emerge as an adult wasp next year. Once it dragged the tarantula into the burrow, I stood over the burrow for over an hour, with camera at the ready, but the wasp didn’t come out. I suspect that it had a lot of cell construction, tunnel-filling, and back-filling work to do to make this gopher/snake hole a home. And for me, like Tom Petty sang, it was: ... time to move on, time to get going What lies ahead, I have no way of knowing... by Dan Sandri Pepsis Tarantula Hawk drags her paralyzed prey along the trail. by Dan Sandri Pepsis Tarantula Hawk drags her paralyzed prey to the burrow she found, then inspects the burrow again. by Dan Sandri Pepsis Tarantula Hawk pulls the tarantula into her burrow. by Dan Sandri Pepsis Tarantula Hawk pulls the tarantula into her burrow. BACK TO LIST

Wildflower Mount Diablo Chia Scientific Name: Salvia columbariae Family: Lamiaceae (Mint Family) Blooms: May - Jun Color: Blue-Purple Annual herb Native Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Mike Woodring

Wildflower Mount Diablo Purple Mouse Ears Scientific Name: Mimulus douglasii Family: Phrymaceae (Monkeyflower Family) Blooms: Feb - Mar Color: Blue-Purple Annual herb Native Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants iNaturalist observations

Wildflower Mount Diablo Gambel's Milkvetch Toxic Scientific Name: Astragalus gambelianus Family: Fabaceae (Legume Family) Blooms: Mar - Jun Color: Blue-Purple Annual herb Native Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Daniel Fitzgerald Daniel Fitzgerald Leaf detail Daniel Fitzgerald Full plant view

Live Oak Campground Map

Wildflower Mount Diablo Brewer's Red Maids Scientific Name: Calandrinia breweri Family: Montiaceae Blooms: Mar - Jun Color: Red-Pink Annual herb Native Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants

Summit Museum Summit Museum Visitor Center Visitor center telephone: 925-837-6119 Open Daily 10 am to 4 pm There is a park entry fee. Admission to the museum is free. You can call the park at 925-837-2525 to confirm that both the park and museum are open and verify hours of operation. See the Park Location page for directions Also visit the Mitchell Canyon Visitor Center on the north side of the mountain Diablo Peak | Cris Benton 15-million year old oysters decorate the buildings exterior walls. The Summit Visitor Center is located in the historic stone building atop Mount Diablo's highest peak. The tower was constructed during the late 1930's of fossiliferous sandstone blocks quarried in the park. Renovated in 2010, the Visitor Center highlights the cultural and natural history of Mount Diablo State Park. Also see the article on the history of the Summit Building, " The Mount Diablo Summit Building " by Linda Sanford, reprinted from the Mount Diablo Review . Exhibits Impressive exhibits chronicle the history of the mountain and capture its majesty. A rock wall with an instructional video examines the geological forces that created the mountain. Panels describe the Native American history of the region. A diorama, complete with native sounds, offers an overview of the park's ecosystems. A model of the mountain acquaints visitors with important park locations. Splendid photographs enhance the visitor's experience. In addition to the exhibits, the summit museum features a gift shop and audio-visual room. An elevator is available from the lower level entrance to the upper museum floor and observation roof. Check in at the lower level Welcome Desk. Observation Deck On the walk up the circular stairway to the observation deck, visitors are treated to a look at ancient marine fossils embedded in the sandstone walls of the summit building. In the rotunda, they are reminded of Mt. Diablo's importance as a survey point. Above the rotunda is a beacon, historically important to aviators and now lighted once a year on December 7 in memory of those who lost their lives at Pearl Harbor. Idaho visitor examines fossil embedded in the building stones.

Wildflower Mount Diablo Rosy Sandcrocus Scientific Name: Romulea rosea Family: Iridaceae Blooms: Mar-Apr Color: Red-Pink Perennial herb Introduced There is a high risk of this plant becoming invasive in California according to Cal-IPC. Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Daniel Fitzgerald Daniel Fitzgerald Daniel Fitzgerald

Wildflower Mount Diablo Summer Lupine Scientific Name: Lupinus formosus Family: Fabaceae (Legume Family) Blooms: May Color: Blue-Purple Perennial herb Native Jump to Blooming Now Blue / Purple Red / Pink White Yellow / Orange Invasive Plants Daniel Fitzgerald