Clouded beetles amidst spectacular scenery

“Westerly from Westgard Pass is a view equaled in few parts of America. In the middle distance, a dozen miles away and nearly a mile below, lies the fertile Owens Valley, extending at right angles north and south over a hundred miles, and on the farther side, distant a score of miles, tower the snow-clad Sierras, with serrated crests and symmetric domes and peaks outlined against the sky at an approximate height of two and one-half miles vertical above the level of the ocean, and extending north and south far as the eye can see. The vision is rich reward for a journey of a thousand leagues.”—A. L. Westgard, March 1915

View of Westgard Pass from higher up in the White Mountains near Ancient Bristlecone Pine Forest.

View to Westgard Pass from higher up in the White Mountains near Ancient Bristlecone Pine Forest.

After a morning spent searching for Crossidius coralinus caeruleipennis (perhaps the most sublimely beautiful of the subspecies) in the high desert sage of the wide open Owens Valley floor near Bishop, California, we made the short drive south to Big Pine, turned sharply left, and began the slow, twisting ascent through a narrow gap between the White Mountains to the north and the Inyo Mountains to the south. Eventually reaching an elevation of 7,313 ft,  Westgard Pass serves as access to Earth’s oldest living things! and, in doing so, provides some of the most striking scenery in the entire Basin and Range Province of eastern California.

Westgard Pass, Inyo Co., California.

Chrysothamnus viscidiflorus (small plants with yellow flowers) host Crossidius hirtipes nubilus adults.

Field mate Jeff Huether and I no doubt wanted to see the grotesquely beautiful trees growing in Ancient Bristlecone Pine Forest and were happy to enjoy the magnificent scenery along the way, but our trek to Westgard Pass had also a strictly entomological purpose—to search for Crossidius hirtipes nubilus, among the most uniquely colored and geographically restricted of the C. hirtipes subspecies. Approaching the summit, the narrow, rocky gorge opened up to a broad expanse of pinyon/juniper woodland, and nestled among the ubiquitous sage we found the plant we were looking for—yellow rabbitbrush (Chrysothamnus viscidiflorus) in full bloom.

Crossidius hirtipes nubilus (male) on flowers of Chrysothamnus viscidiflorus.

Crossidius hirtipes nubilus (male) on flowers of Chrysothamnus viscidiflorus (field photo).

It took a while, however, before we found the beetles that we were looking for. Robust gray rabbitbrush (Ericameria nauseosa) plants in full bloom conspicuously dominated the roadsides and demanded our initial attentions, but our only reward was the widespread Crossidius ater. Not even a single Crossidius coralinus specimen could be claimed as consolation. Still, we knew the real quarry was further back from the roadsides, on the much smaller and less conspicuous yellow rabbitbrush that serves as an adult host for Crossidius hirtipes and most of its subspecies. Once we turned our attentions to these smaller plants we found the first adult fairly quickly, but precious few were seen considering the many plants that we examined until we finally zeroed in on one area just south of the summit where the beetles seemed to occur with slightly greater frequency. While not numerous, we eventually found enough beetles for us to declare, “Let’s go see the bristlecone pines!”

In addition to their longer antennae, males are distinguished by xxx.

In addition to longer antennae, males are distinguished by less extensive clouding (studio photo).

This subspecies is among the most distinctive of all the C. hirtipes subspecies due to the combination of dark reddish-brown coloration and extreme, dark clouded area of the elytra (Linsley & Chemsak 1961). It most closely resembles C. h. rhodopus, which occurs further north in the Mono Basin, but that subspecies is not as dark and lacks the extensive clouding of black on the apical portions of the elytra.

Females have the elytral markings xxx.

Females have the markings greatly expanded to almost completely cover the elytra (studio photo).

The dark clouding actually represents an expansion of the dark stripe found along the suture of the elytra of many C. hirtipes subspecies, most of which exhibit sexual dimorphism in the degree to which this stripe is developed. In some subspecies the stripe is present in the females but absent in the males, while in others the stripe is present in both but more fully developed in the female. In C. h. nubilus the sutural stripe reaches an extreme state of development, covering much of the apical two-thirds of the elytra in the male and being so greatly expanded in females that almost the entire elytra are covered except for two small subbasal patches revealing the ground color of the elytra.


Linsley, E. G. & J. A. Chemsak. 1961. A distributional and taxonomic study of the genus Crossidius (Coleoptera, Cerambycidae). Miscellaneous Publications of the Entomological Society of America 3(2):25–64 + 3 color plates.

Copyright © Ted C. MacRae 2014

What was that insect?

Yesterday I posted an identification challenge of a different sort. The main subject in the photo was a jewel beetle (family Buprestidae), but there was also another insect in the photo—a small parasitic wasp sitting on the branch below the beetle. Some of you saw it—Charley Eiseman was the first and correctly guessed it was a member of the family Encyrtidae, earning 5 pts, and Wikispecies editor gets 5 pts for further identifying it as a member of the genus Metaphycus. Honestly, I took several shots of the beetle and never saw the wasp until I examined the photograph during processing. I’m not certain, but I think the small object next to the wasp could be a scale insect (family Coccidae), which are known hosts of Metaphycus spp.

Of course, there is still the jewel beetle, and it wouldn’t be fair for me to award points for the wasp but not the beetle. Heath gets 5 pts for first identifying the beetle in the genus Agrilus; however, nobody was able to identify the species as A. granulatus—commonly associated with cottonwood and poplar (Populus spp.) across North America. Since Charley was the only person to mention both the beetle and the wasp, I’m going to give him a tie-breaking bonus point and declare him the challenge winner.

Populations of A. granulatus have been assigned to several subspecies—the beetle shown here (photographed June 2013 at Beaver Dunes, Oklahoma) represents the nominate form—restricted to the U.S. east of the Rocky Mountains, where it breeds in native eastern cottonwoods (P. deltoides) and introduced Lombardy poplars (P. nigra var. ‘Italica’). Agrilus granulatus is often confused in collections with A. quadriguttatus, but that species is associated with willow (Salix spp.) and can be further distinguished by the less dense pubescence of the lower face not obscuring the surface; the pronotum with the lateral margins evenly rounded and not strongly sinuate at the base, the median channel less distinct, and the lateral depressions scarcely pubescent; and the elytra more gradually narrowed posteriorly with the tips more acutely rounded and more coarsely serrulate and the pubescent spots less distinct (Fisher 1928).

Here are a few more photographs of the jewel beetle (without the wasp):

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma

Agrilus granulatus granulatus on Populus deltoides | Beaver Dunes, Oklahoma


Fisher, W. S.  1928. A revision of the North American species of buprestid beetles belonging to the genus Agrilus.  U. S. National Museum 145, 347 pp.

Copyright © Ted C. MacRae 2014

Earth’s oldest living things!

Westgard Pass

A view down towards Westgaard Pass.

I’ve mentioned before that I am never happier than when I am in the field, especially when it’s an extended insect collecting trip. One problem I face on these trips, however, is the conflict between my desire to stay focused on the task at hand (collecting insects) versus indulging my broader natural history interests—landscapes, botany, geology, etc. The urge to explore increases the further west I go, as the landscape becomes more diverse and unfamiliar, and reaches its zenith in the king of landscapes that is California.

Ancient Bristlecone Pine Forest

Approaching Ancient Bristlecone Pine Forest from the south.

During our Great Basin collecting trip last August, field mate Jeff Huether and I visited the White Mountains near Bishop to look for Crossidius hirtipes nubilus, an isolated subspecies of longhorned beetle (family Cerambycidae) known only from the vicinity of Westgaard Pass. At 7,282′ elevation, the landscape around Westgaard Pass is beautiful enough, but we also knew that lying another 3,000′ above us was one of the most stunning landscapes that anyone even remotely interested in natural history could possibly imagine—Ancient Bristlecone Pine Forest (ABPF)!

Ancient Bristlecone Pine Forest

Entering the Ancient Bristlecone Pine Forest.

While Jeff had previously visited this magical place, I’d not yet had the chance despite my five years in California back in the 1990s (too many places, not enough time!). I had mentioned this to Jeff earlier in the trip, so with small but adequate series of C. hirtipes nubilus in our bottles Jeff suggested we take a break from insect collecting and visit ABPF. I was excited enough about the prospect of seeing these ancient trees, but I could not have anticipated just how bizarre and otherworldly a landscape we were about to see!

Bristlecone Pine Ancient Forest

Bristlecones growing in the harshest sites tend to be the longest-lived.

ABPF is, of course, named for the Great Basin bristlecone pines (Pinus longaeva) that occur here, one of three closely related pine species found in scattered, high mountain localities across the western U.S. and widely regarded to be the longest-lived of any non-clonal organism. The oldest known individual tree in the world, measured in 2012 at 5,062 years of age, is a bristlecone that occurs at this very site (although its identity and precise location are kept secret—for sadly obvious reasons), and nearly two dozen additional trees exceeding 4,000 years of age are known to occur here as well. True—there are clonal plants such as creosote bush and quaking aspen that are believed to survive as distinct genotypes for longer periods of time. However, the individual plants themselves are short-lived and quickly replaced by new sprouts from the clonal root mat. A 6,000-year old clonal patch of aspen may be technically older than a 4,000-year old bristlecone, but in my mind only the latter is bona fide ancient!

Ancient Bristlecone Pine Forest

Most older bristlecones have trunks with large sections of exposed dead wood.

In the White Mountains, bristlecone pines are restricted to exposures of white dolomite (giving the mountains their name), usually between 10,000′ and 11,500′ in elevation. We could see the sharp demarcation between the white dolomite—heavily colonized by bristlecones—and non-dolomitic bedrock colonized by shrubs but devoid of pines as we approached ABPF from the south.

Bristlecone Pine Ancient Forest

Dead bristlecones stand with main limbs intact for centuries.

Great Basin bristlecones occur also in the Inyo Mountains and other high mountains sites in Nevada and Utah. Most of these other sites have milder climates that offer more favorable growing conditions for the trees, and as a result the trees at these sites grow faster but—ironically—also die younger (Lanner 1999). Greater moisture availability and soils with more organic matter favor denser stands of trees as well as a richer shrub layer. This results in a greater fuel load that can carry fires, which are generally absent in the White Mountains groves with their widely spaced trees and sterile, rock substrate. Moreover, the harsh, dry conditions in the White Mountains inhibit the growth of fungi that can penetrate and colonize trunks at injury points, and there is a general lack of other threats that exist at milder sites such as bark beetles, sapsuckers, and even porcupines!

Bristlecone Pine Ancient Forest

Bristlecone Pine Ancient Forest

Unlike other pines growing at high elevations, such as whitebark pine (Pinus albicaulis), which develops an almost shrubby, beaten-down form in the face of constant battering by fierce winter winds, Great Basin bristlecones grow solidly upright and develop massive branches supporting a spreading crown. As the trees get older, their outer branches become long and pendulous, drooping under the cumulative weight of numerous, tightly packed needle clusters that can remain on the tree for up to 40 years! (The needles of most pines are shed after just a few years.)

Pinus longaeva male catkins

Bright, reddish-brown male catkins emerge near the tips of the densely needeled branches.

Most of the trees at ABPF grow on steep slopes of barren dolomite with virtually no soil layer, and the trunks of older trees usually bear large sections of exposed dead wood. Over the course of their very long lives, erosion of the rocks on the steep slopes around them gradually exposes roots, killing them and resulting in death of the trunk sections and branches that they feed. In many cases nearly the entire trunk is dead, but the tree lives on in a narrow ribbon of living bark snaking or spiraling up the trunk and connecting the last surviving roots to a single living branch.

Pinus longaeva sapling

A bristlecone sapling represents the promise of enduring life in the face of harsh conditions.

Eventually death does come, but it can take centuries for the dry, cold air to decompose the standing carcass and even millenia for the hard, resinous wood to break down completely once the tree finally does fall. The oldest existing wood at ABPF has been dated to more than 9,000 years old! It is almost incomprehensible to imagine stepping over a log that began life as a sapling shortly after the last glacial retreat and the arrival of the first humans to step foot in North America!

Pinus longaeva cone

Bristlecones are named for, well.. the bristles on their cones!

Why do Great Basin bristlecones live so long? It’s tempting to presume that the dry, high elevation environment, with its long, harsh winters and short, cool growing season enables an unusually slow metabolism that somehow translates to longevity. There is no evidence to support this, however. Perhaps characteristics such as its extremely decay-resistant wood play a part, but there are a few other species of pine that are also extraordinarily long-lived, yet still fall far short of the great ages that can be attained by Great Basin bristlecone pine. These include limber pine (Pinus flexilis), which co-occurs with Great Basin bristlecone pine in the White Mountains, but this species maxes out at about 2,000 years of age. Likewise, Rocky Mountain bristlecone pine (Pinus aristata) in Colorado can reach around 2,500 years of age. (Interestingly, limber pine occurs here as well, but in this area it reaches at best only about 1,500 years of age.) Even Great Basin bristlecones themselves growing at other sites, as noted above, are unable to match the longevity of the trees growing here in the White Mountains. Perhaps, as California conifer expert Ronald Lanner remarked, the question is not why these trees “live so long”, but why they “take so long to die”.

Bristlecone Pine Ancient Forest

A raven perches atop a fine, massively trunked specimen.


Lanner, R. M. 1999. Conifers of California. Cachuma Press, Los Olivos, California, 274 pp. [description].

Copyright © Ted C. MacRae 2014