Lined Buprestid Beetle

Howdy, BugFans,

BugFan Freda photographed this astonishing beetle while she was on vacation Up North. It’s in the family Buprestidae, the Metallic wood-boring beetles, aka the Jewel beetles. The larvae, which have a flat area behind their heads, contribute another name—the Flat-head borers. It’s a family we haven’t visited for a long time, but one that’s garnered some attention in the past decade or so because of a small, sparkly Buprestid called the Emerald ash borer (EAB) that’s in the process of killing 99.9% of Wisconsin’s ash trees. There are about 750 species of Buprestids in North America and almost 15,000 globally.

Introducing the Lined Buprestid (Buprestis striata) – a story in three (diminishing) parts.

Buprestids—The Family

The BugLady loves the etymology of entomology (well, the etymology of just about anything, really). Buprestidae comes from buprestis which is Greek for “burn cow,” referencing a poisonous insect. According to Nicolay and Weiss, in an article published in the Journal of the New York Entomological Society in 1918, “’The Buprestis of the ancients, as its name signifies in Greek, was a poisonous insect which being swallowed with grass by grazing cattle, produced a violent inflammation, and such a degree of swelling as to cause the cattle to burst.‘ (Harris). Linnaeus applied this name to the family in spite of the fact that none of its members is poisonous, and they are rarely if ever taken on grass.” Apparently, the Buprestids were being blamed for the antics of Blister beetles, in the family Meloidae.

Buprestids have long, flat, bullet-shaped bodies. Their elytra (wing covers) are often pitted, ridged, or lumpy, and their antennae are serrate, but are often tucked close to their body. Their pale, legless larvae mostly live and feed within their host plants and are seldom seen. Most of the wood-boring Buprestid species favor dead or dying trees, but some species prefer herbaceous plants, and a few make galls. The adults of many species are day-flying (they’re strong flyers) and feed on nectar, pollen, or vegetation.

Although many are drab in color, some are spectacular:

The iridescence results not from pigments, but from the play of light on nanostructures in the cuticle, which explains why you experience a changing light show as you walk around the insect. Alas, for them, their colors make them highly desirable to insect collectors and as living jewelry (yes, on tiny chains, attached to pins). Some people use the elytra to create often-massive artistic displays. Spectacular, yes, but also beautiful when still attached to a living organism. There’s a brisk online trade in Buprestids and other dramatic insects, and the excuse that “Well, it was dead when I bought it” is both specious and self-serving, since each purchase sends someone back out to capture more.

Female Buprestids oviposit on tree bark and in bark crevices, and when the eggs hatch, the larvae tunnel into the tree and nibble winding tunnels called galleries into the wood under the bark. Their tunnels are packed with sawdust and frass pellets that they leave behind as they travel. They may live as larvae for several years before pupating under the bark and emerging as adults.

Some wood-boring buprestids are famous for making surprise appearances. Seems that if it’s in a tree when it’s harvested, the lumber-drying process may cause a larva to go into diapause/dormancy/developmental delay—sometimes for many years—before it completes its metamorphosis and emerges from flooring or a desk or the wooden framework of a building. The (known) record was a beetle that emerged 51 years after the larva was believed to have entered the wood.

Lined Buprestid—The Genus

There are about 80 species in the genus Buprestis worldwide – 26 in North America – and some are pretty spiffy:

Their life stories are typical, with larvae spending one or more winters under the bark of dead and dying trees (mostly conifers, but some use beech, poplar, maple, and oak). Pupae and adults may also overwinter there. The larvae contribute ecosystem services by assisting in the decay of logs, and their tunnels host saprophytic fungi that break down cellulose, which also makes it easier for them to feed. They don’t technically kill trees, but they might hurry the demise of damaged ones. Adults die soon after mating.

Of course, their taxonomy is in a state of flux, and apparently has been for a while. Back in 1918, Nicolay and Weiss wrote of a taxonomist who made an exhaustive study of the genus in 1909 and who was, in their opinion, so carried away by all the different color variants that he described a whole bunch of questionable new species, some of whose ranges coincided with state lines. (“The result of this was a multitude of new species, the validity of most of which may be justly questioned by students who demand at least one good, constant character.”) In reference to the beetles’ color, they also pointed out that “Mr. W. J. Chamberlin, who has carried on extensive experiments in the breeding of various buprestids, has secured from one female of Buprestis aurulenta, a series of forms ranging from entirely green to a uniform bronze.”

Here are some of the colors that the Golden buprestid (Buprestis aurulenta) comes in:

Lined Buprestic—The Species

Buprestis striata (the species name, striata, comes from the Latin word “striatus,” meaning grooved, furrowed, or striped) is found in a patchwork of mostly-eastern states from Florida to Texas to Minnesota to Maine, plus southern Canada. The species are most fond of pine, but has been found on spruce and hemlock. They are one-half to three-quarters of an inch long and, according to bugguide.net, and come in “copper, metallic purple, or bright rainbow hues.”

Adults emerge from under the bark in spring, looking for a conifer, preferably a pine, that’s been dead for a year or so. According to Evans in Beetles of Eastern North America, the “Larva develops in solid or rotten pine. Adults active in spring and found on needles or in beach drift.” Adults sometimes excavate the sapwood of living wood.

Nicolay and Weiss present us with two wonderful anecdotes. One is a report from Europe of a species of Crabronid/Square-headed wasp, Cerceris bupresticida, that specializes in collecting and caching Buprestid beetles for their egg chambers (members of the genus Cerceris are sometimes called “beetle wasps”), “Dufour unearthed in a single field, thirty nests of Cerceris bupresticida which were filled with several species of Buprestis comprising 400 individuals and none of any other genus (Packard). In a fascinating account of the habits of Cerceris bupresticida, Fabre quoting Dufour ……. states that the cleanliness and freshness of the beetles which she buries testify that they are seized just as they emerge from their wooden galleries.” Dufour was a 19^thcentury entomologist. Here she is with a Buprestid.

The second story involves an account from 1890 of a beetle that apparently emerged in a clothing store “and had died after cutting eight holes through a pair of heavy woolen pantaloons. The editor replied that it had probably emerged from wood-work and had cut the clothing in an effort to escape.”

Thanks, Freda.

BIG Shout-Out to the folks at UWM who make each episode look great in the archives on the UWM Field Station website and who have an inordinate number of links to deal with this time.

The BugLady

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