Beetles - Coleoptera
Imagine you were tasked with making a bingo ball machine, and creating a ball for each animal species described by science. You’d need to write 1.2 million names on little balls…and a full 25% of them would be beetles. In the San Francisco Bay, we have several hundred beetles present, of remarkable diversity. Known for their hard, rounded shells beneath which sit folded wings, these creatures are sometimes loved, sometimes reviled. Weevils can lay waste to crops in short order, and beetles like the emerald ash borer or California’s bark beetles can kill trees, increasing fire risk and severity. But ladybugs and June beetles draw adoring fans, and scarab beetles were revered in Egypt for centuries. In the invertebrate pet trade, beetles are consistently beloved in all corners of the Earth. Anywhere you find insects traded, you’ll find beetles. Just like worms, their larvae till the soil—like flies, they break down carrion and waste—like bees, they are important pollinators. What they all share is a a hardened, curved shell, and wings folded neatly underneath…
Bronze beetle - Chrysolina bankii
These bold and bawdy beetles, often known as bronze beetles, were broadly introduced to the East Coast of North America from the Mediterranean. These travelers have only recently been found to take up a permanent residence in the San Francisco Bay Area, according to A.J. Gilbert in the Pan-Pacific Entomologist. Fortunately for us, they appear destined to become another harmless, ornamental visitor to our parks and gardens. Like all leaf beetles, these golden critters are fully herbivorous, but their appetites are not so great for them to become a problematic pest.
Seed Beetle/Bean Weevil - Subfamily Bruchinae
A small leaf beetle, Seed Beetles were mistaken for weevils on account of their habit of eating the same foods we humans prefer. As larvae, a seed beetle typically inhabits a single grain or bean, using its empty husk as shelter before emerging as an adult. The seed beetles native to the Bay Area are rarely larger than 5mm, and enjoy spending time in blooms and dining on nectar and pollen before finding a mate and laying eggs near a growing seed or bean. Because of humanity’s proclivity to trade beans and grains, hundreds of seed beetle species have been introduced to nonnative environments around the world.
Soldier Beetle - Podabrus cavicollis
A common family of beetles in the Bay Area, soldier beetles can be found prowling flowers, stems, grasslands and the undergrowth. Omnivorous, these slender insects prey upon small insects as well as visiting select favorite flowers to dine on nectar and pollen. They may be considered among the most beneficial of garden beetles, as they are efficient pollinators and play a role in pest control. Their larva resemble ladybug larva, and are also active hunters. These beetles are ready fliers, quickly taking to the wing when they feel threatened, and many species can secrete or even spray a smelly and acidic compound from their rear ends.
Seven-Spotted Ladybug — Coccinella septempunctata
The darling of many a gardener and a subject of fascination for children of every generation, ladybugs stand out with their royal red coloration. Ladybugs distinguish themselves from other beneficial insects by being the most widely available and frequently purchased garden insect. Their voracious appetites for common garden pests—notably, aphids—has seen them introduced to gardens in every continent. The Seven Spotted Ladybug originated in Europe, where it is the most common of its genus, which includes black, brown, yellow and orange ladybugs, and was brought to North America hundreds of years ago. Paralleling the travels of American colonists, this adaptable insect thrives in heavily managed lands. Today, the Seven Spotted Ladybug is the state insect of 5 US states (Delaware, Massachusetts, New Hampshire, Ohio, and Tennessee). These beetles survive the winter by clustering together in swarms and entering diapause, a kind of hibernation. Gardners mimic this by putting store-bought ladybugs in their fridges, placing them in their gardens as soon as a pest outbreak is spotted.
Fire colored beetle - Dendroides canadensis
Fire colored beetles are representatives of the Polyphaga suborder of beetles, from the Latin meaning “eating many.” These cosmopolitan beetles dine heartily on fungus, plant materials, and animal matter alike, though they prefer to scavenge as they are poor hunters. Their larvae live under loose bark of dead or dying trees, likely eating both the other invertebrates that live there and the fungus that digests the wood. Adults dine on nectar and pollen for an energy-rich snack as they seek mates. Little is known about this diverse and widespread group of beetles, making them an ideal field of study for amateur and professional entomologists. Who knows what mysteries live amidst the over 100 species of fire-colored beetles?
Carpet beetle/skin beetle, Anthrenus verbasci
Though they may resemble a funkadelic carpet, these tiny beetles get their name for their propensity to infest people’s carpets. These minute beetles can eat a great variety of products bought and sold, including fur, wool, leather, felt, and many fabrics. They happily consume keratin, which is in many organic items, and is shed by humans as a main component of our hair and skin, giving these beetles their alternate name, “skin beetles.” In a human environment, their favorite foods include down pillows or comforters (as feathers contain keratin) and taxidermied animals!
In nature, these tiny beetles (measuring just 3mm as adults) are a major part of the decomposer community, helping break down hair, skin, fur that animals may have shed, as well as corpses. They can be found in bird’s nests, where they eat the feathers shed as birds grow up.
Click Beetle - Family Elateridae
These elongated beetles possess a unique defensive mechanism: it can separate two segments of its thorax and suddenly and swiftly, “click” them back together, propelling the beetle off whatever surface it finds itself on. In this way, it can launch itself away from predators, or right itself should it be flipped on its back. Typically, click beetles are consumers of plant material, and rarely become crop pests. Several click beetle species are bioluminescent, and can be seen in Texas. Dozens of different click beetle species can be found in California alone!
Flea beetle - Subfamily Galerucinae
These small leaf beetles are easy to identify because of their enlarged hind-legs. They use these beefy appendages to jump away from danger, giving them their name. These beetles are notorious for chewing small, circular holes in plants, particularly leafy greens people like to grow in gardens. But their appetite for plants has been put to beneficial practice as well: the “leafy spurge flea beetle,” was introduced to Colorado to help control the noxious weed, leafy spurge, for which it is named. When a flea beetle infestation has presented itself, some farmers have learned to plant radish, which lures away these hungry bugs. The radish is still usable, as they’re unable to damage the plant significantly.
Snout Weevil - Family Curculionidae
Snout weevils are known for their long rostrums, from which their antennae are fused! At the end of these long appendages are their chewing mouthparts—they can chew into seeds, through roots or shoots of plants. Some species of snout weevils drill holes in nuts like acorns, in which they lay their eggs. When the larvae hatch, they find themselves protected and surrounded by food. One notorious weevil is the boll weevil, a serious pest to cotton crops. When this weevil arrived in Enterprise, Alabama, it soon began wiping out entire crops of cotton. An entrepreneur used this calamity to encourage farmers to diversify their plantings towards peanuts, legumes, and other cash crops. Shortly thereafter, the town’s farmers were able to pay off the debts incurred by the weevil damage, and henceforth maintained a more profitable, sustainable, and diverse agriculture regime. In honor of the weevil that served as a catalyst for improvement, the town erected the Boll Weevil Monument in the center of town.
Eucalyptus Tortoise Beetle - Trachymela sloanei
These shiny beetles depend on their namesake, eucalyptus trees, for their survival. Under mysterious circumstances, they were discovered in California in 1998, over a century after the Australian tree species began to grow in the state. As larvae and adults, they have a healthy appetite for the nutrient-poor eucalyptus leaves, which are toxic to many creatures. As in California, it has no natural predators, these beautiful beetles can become serious pests to stands of eucalyptus, decimating their leaves. In the Bay Area, the cooler weather helps moderate their populations. Like other tortoise beetles, Trachymela sloanei have small heads that they can pull within their large, hardened shell for protection. This, along with their clumsy gait, gives their subfamily the name “tortoise”.
Cylindrical Weevil - Scaphomorphus trivittatus
These true weevils are plant eaters, who slowly draw nutrients from seeds, fruits, and stems with a proboscis. Of the 6,000 species of true weevils, dozens are considered, “economically significant,” meaning they pose a threat to crops and livelihoods. Though the species of weevil pictured here, Scaphomorphus trivittatus, is not widely destructive, its relatives, wood boring beetles, can do some serious damage, especially to the forestry industry. Their larvae have the ability to digest wood, and they can pose a risk to tree plantations and any wood that is improperly treated or stored. Weevils are often named for the very tight relationships they have with their preferred food: for example, grape weevils prefer grape leaves, palm weevils prefer palm trees, sweet potato weevils, rice weevils, and so on. To the great benefit of gardeners and agronomists alike, scientists have discovered species of parasitic nematodes that target specific weevil species, and as a result, one form of biological control for a weevil infestation involves spraying your garden with nematodes!
Coyote Brush Beetle - Trirhabda flavolimbata
This gleaming jewel, Trirhabda flavolimbata, is easily distinguished by the sheen of its shell and its love for the coyote brush. The coyote brush, a dominant shrub species for much of California’, scrubland, constitutes most of beetle’s diet both as larvae and adults. If you look closely, you might find one shrub with dozens of beetles or larva, slowly breaking down the waxy leaves. Coyote brush has become an invasive species in Australia, and these beetles were studied to possibly be introduced to the continent to help control the spread of the shrub. However, researchers at Queensland Department of Lands determined that the beetle foraged too broadly on other species of plant to be considered for introduction. Much remains unknown about the Coyote Brush Beetle: why does it exhibit such glittering coloration?
Ground beetle - Genus Leistus
Ground beetles may be considered the unsung heroes of our farms and gardens—not taking the spotlight the way vaunted ladybugs do, but performing all the same hard work. Unlike ladybugs, these beetles feature dark coloration, they are mostly active at night, and they move quickly to hide, but like ladybugs, they consume great quantities of garden pets. Though some ground beetles have wings, they rarely fly, using their strong and long legs to crawl, burrow, and climb. They love to eat common pest species both as larvae and as adults, feasting on aphids, larvae of other insects, mites, and more. Agronomists also consider ground beetles beneficial for their ability to consume weed seeds that are stored in the soil.
Golden Net-Winged Beetle - Dictyoptera aurora
This strikingly beautiful red beetle gets its Latin name (Dictyoptera aurora) from Roman goddess of dawn, and understandably. The bright red color suggests a distasteful (or poisonous) meal to potential predators. These beetles call coniferous and mixed forests across northern Eurasia and North America home. Larvae feed on decaying wood, while adults enjoy nectar, pollen, and small insects. To find these beetles, search a mature forest on a calm day. Perhaps their potent poison explains why they are not easily startled. The red coloration they carry as a warning is so effective that several other species, such as the pyromorpha moth, mimic these colors to fend off predators.