bufface's Identifications

Fingertip shows the very small size of this metallic beetle found walking on a blade of grass.

Leaf Beetles (Family Chrysomelidae) are "one of the largest and most commonly encountered of all beetle families. Numerous subfamilies are recognized, but the precise taxonomy and systematics are likely to change with ongoing research and DNA testing. Adult and larval Leaf Beetles feed on all sorts of plant tissue." https://www.inaturalist.org/taxa/51146-Chrysomelidae

Field Guide to California Insects, by Kip Will, J. Gross, D. Rubinoff , J. Powell, 2nd ed., 2020, pp. 256-260.
Leaf Beetles (Chrysomelidae) family: "400+ species in California. Beetles in this family are often small, oval, brightly colored and shiny metallic." p. 256

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Cucujiform Beetles (Infraorder Cucujiformia): Cucujiformia is an infraorder of polyphagan beetles that represent most plant-eating beetles.

Field Guide to California Insects, by Kip Will, J. Gross, D. Rubinoff , J. Powell, 2nd ed., 2020

BugGuide: Arthropods: Photos of Insects, Spiders & Their Kin (US & Canada), clickable categories or use search bar (scientific name): https://bugguide.net/node/view/3/bgpage

Cucujiform Beetles (Infraorder Cucujiformia)
Taxonomic chart of Cucujiform Beetles. Cucujiformia is an infraorder of polyphagan beetles that represent most plant-eating beetles. https://www.inaturalist.org/taxa/372852-Cucujiformia

The infraorder contains the seven superfamilies:

Chrysomeloidea (~7 families including longhorn beetles and LEAF BEETLES)
Cleroidea (checkered beetles, bark-gnawing beetles and soft-winged flower beetles)
Coccinelloidea (15 families, includes Lady Beetles and fungus beetles)
Cucujoidea (~27 families)
Curculionoidea (~8 families primarily consisting of weevils and also including snout beetles and bark beetles)
Lymexyloidea (ship-timber beetles)
Tenebrionoidea (formerly "Heteromera") (30 families including blister beetles and ant-like beetles)