‘Tis the Season for conifers to come indoors, so here are two beetles and a primitive wasp whose larvae make their living chewing on assorted evergreens.
Dandelion Anthaxia Beetles
Every spring the BugLady sees these Dandelion Anthaxia Beetles on wild geraniums, and this year, with the help of Arthur V. Evans’ fabulous Beetles of Eastern North America, she did some serious picture-keying and was surprised at what she found. This dull, stubby beetle is in the family Buprestidae—definitely not a poster child for the usually-svelte, often glittering Metallic wood-boring beetle family (a.k.a. jewel beetles). See Flatheaded Poplar Borer (Family Buprestidae) for more about buprestids.
The BugLady is out on her usual taxonomic limb here. She thinks that this beetle is in the genus Anthaxia, and she’s guessing that it’s Anthaxia inornata (and not the very similar Melanophila accuminata, which is too bad, because Melanophila accuminata has super powers). There are about 40 hard-to-differentiate Anthaxias in North America and more elsewhere. The DAB is found across the northern tier of states and into Canada.
DAB larvae feed in galleries (tunnels) that they excavate beneath the bark of pines and spruce, and Kaufman, in Field Guide to Insects of North America, adds that they are “suspected to bore in branches.” They must be minor players, because their on-line presence is dominated not by exterminators, but by biodiversity and museum lists and by state agricultural reports dating back to the last quarter of the 1800’s. Adults eat the pollen of a variety of late spring/early summer wildflowers and are here shown on wild geranium and wild calla, as well as dandelion. According to the Report of the Minister of Agriculture and Food by the Ontario Department of Agriculture and Food (1895), “The habits of this pretty little species appear to be somewhat different than other species of Anthaxia, which are generally obtained by beating trees during the summer, whereas this species is usually found earlier in the season, and nearly always on flowers, such as trilliums, etc.”
(A quick word about the look-alike Black Fire beetle/fire bug Melanophila accuminata. Using infrared detectors tucked under its elytra (hard wing covers) and possibly smoke detectors on its antennae, these beetles locate still-warm-to-the-touch conifer trunks following forest fires. There they congregate and mate—their eggs are laid in the recently-smoldering trees, and the larvae feed on wood that’s been de-toxified by fire.
Small Cedar Borer
This Small Cedar Borer (Atima confusa) joined the list of Porch Light Bugs in mid-May. It’s one of the Cerambycidae (Long-horned beetles), a family whose often-dramatic antennae have gained fans for it world-wide. The genus is largely western; only this species occurs in the East. The subtly-lovely, chunky SCB, which is just under a half-inch long, is much fuzzier than the BugLady’s picture suggests (click on the photos).
SCB lay their eggs under the bark of sick/dying cedar and juniper trees and the larvae dig around just below the bark layer, leaving the tunnel behind them full of frass (BugPoop) as they go forward. They pupate under the bark, too. Adults are active in both spring and fall, and they can overwinter as either larvae or adults. They may surprise us by emerging indoors from improperly seasoned poles and woodwork.
The Introduced Pine Sawfly (Diprion similis) (Family Diprionidae, the conifer sawflies) found its way to our shores (Connecticut) in 1914, most likely arriving in a shipment of packing material or nursery stock from Holland. It set out to explore its New World, reaching Pennsylvania by 1920, Ontario a decade later, and the southern Appalachians by 1977. Its present range includes eastern Canada and the U.S. from Maine to North Carolina, west through Tennessee to Minnesota and South Dakota, with a disjunct population in the Pacific Northwest. And, this one is considered a pest.
Why? Because its larvae feed on the needles of pines, especially white pine, but secondarily, Scotch, red and jack pines. It can be a problem in white pine plantations and Christmas tree farms because during a population boom, young trees can be killed or, at best, stunted. The good news is that because of pressure from weather, diseases, and a variety of predators (including chickadees) and parasites (including two introduced sawfly-specialist wasps), population booms are uncommon.
There are two generations per year, beginning in mid-spring. Eggs are laid within slits made by the female in the pine needles (their name comes from the female’s serrated ovipositor). Unfertilized females can lay eggs, too, but the results are all male, and overall, there tend to be more males than females in a population. Newly-hatched larvae feed gregariously, splitting up as they get older. Larvae of the first generation eat the tender, outer layers of older needles, but the second generation feeds on old and new needles alike. Pupal cases of Gen 1 are often attached to pine needles, but they may also be found on surrounding vegetation. The larvae of Gen 2 spend the winter in the pine duff below their host tree and pupate the next spring.
Sawflies are primitive members of the wasp/bee/ant order Hymenoptera. Adults of some sawfly families look somewhat bee-like – here are pictures of a male and a female poine sawfly: http://bugguide.net/node/view/968445, http://bugguide.net/node/view/357530/bgpage. They don’t sting. The larvae are caterpillar-ish, and they famously startle when alarmed (so some people enjoy alarming them.