California Native Plant Society
in collaboration with East Bay Municipal Utility District
Other Insects
All writing from May Chen's posts
Crab Spider-
Mecaphesa sp. (family Thomisidae
Its powerful front legs flexed back, a tiny Crab Spider, Mecaphesa sp. (family Thomisidae) has stationed itself on a petal of a buttercup flower.
Members of the family Thomisidae do not spin webs, and are ambush predators. The two front legs are usually long and more robust than the rest of the legs. Their common name derives from their ability to move sideways or backwards like crabs. Most Crab Spiders sit on or beside flowers, where they grab visiting insects. Some species are able to change color over a period of some days, to match the flower on which they are sitting.
Mecaphesa asperata, the Northern Crab Spider is found in North and Central America, and the Caribbean. The ambush predator generally lurks in similarly colored flowers for visitors such as bees and flies. It is similar in appearance to the better-known Goldenrod Spider, Misumena vatia. Mecaphesa can be distinguished in that the carapace, abdomen and legs are covered with numerous short stiff spines.
It is often assumed that Crab Spiders change colors to blend in with their surrounding. The truth is a little more complicated than that.
The spider can change its color between white and yellow to match the flower it is sitting on. The color change takes a few days. Maybe this spider has recently moved over from a nearby yellow flower?
There’s another trick that the spider might be playing that we are not aware of because we cannot see in the ultraviolet (UV) spectrum of light. It’s been discovered that Crab Spiders reflect UV light strongly. Most insects, notably the bees, see UV well, and favor sunlit flowers while foraging. Experiments have shown that flowers that have crab spiders sitting on them actually garner more insect visits than those that don’t! It is thought that perhaps color camouflage in the visible spectrum helps the spiders avoid vertebrate predators (birds, lizards, etc.), while the UV reflectance is useful for attracting insect prey.
Jewel Beetle (Woodboring Beetle)
sub genus Melantaxia (family Buprestidae)
Buprestids are sometimes also called Jewel Beetles because of their glossy, iridescent colors. The larger and more spectacularly colored ones are highly prized by insect collectors. Their elytra have been traditionally used in beetlewing jewelry in some Asian countries. The iridescence common to these beetles is not due to pigments in the exoskeleton, but instead is caused by structural coloration, in which microscopic texture in their cuticle selectively reflects specific frequencies of light in particular directions. Buprestid larvae are known as flathead borers. They bore through roots, logs, stems, and leaves of various types of plants, ranging from trees to grasses. Adult jewel beetles mainly feed on plant foliage or nectar, although some species feed on pollen and can be observed visiting flowers.
Members of the subgenus Melantaxia have an affinity for yellow flowers, such as buttercups and dandelions. I have seen them gather in large numbers to feed and mate on dandelion flowers.
Skin Beetle
A Skin Beetle, Cryptorhopalum sp. (family Dermestidae) is feeding on the pollen of Goldfield flowers.
Dermestidae are a family of Coleoptera (beetles) that are commonly referred to as skin of carpet beetles. Ranging in size from 1 to 2 mm, the beetles typically have clubbed antennae that fit into deep grooves. Most Dermestids are scavengers that feed on dry animal or plant materials, such as skin or pollen, animal hair, feathers, dead insects and natural fibers. The larvae are used in taxidermy and by natural history museums to clean animal skeletons.
Winter Ant
The American Ant, Prenolepis imparis is a widespread North American ant. A dominant woodland species, it is most active during cool weather, when most other ant species are less likely to forage. This species is one of a few native ants capable of tolerating competition with the invasive Argentine Ant, Linepithema humile. They are also aggressive toward other ants and produce abdominal secretions that are lethal to Argentine Ants. Prenolepis imparis is a generalist omnivore. Foragers are known for tending to aphids or scale insects from which they consume excreted honeydew, aggregating on rotting fruit, and exploiting protein-rich sources such as dead worms. The colony enters estivation (a hibernation-like state) and becomes inactive above ground for the warmer months, during which time eggs are laid and brood are reared. Reproductives overwinter and emerge on the first warm day of spring for their nuptial flight.