North America’s Most Beautiful Agrilus Jewel Beetle

For the past few years I’ve spent the summers traveling once a month or so from my home near St. Louis to research plots in western Tennessee. I enjoy these trips immensely—not only are my research and the colleagues that I spend time with fun, but I also get to keep an eye on the progression of the season in one of Missouri’s most interesting (and threatened) natural communities: the southeastern lowlands. Spring sees the emergence of an unusual population of the Festive Tiger Beetle (Cicindela scutellaris) in the area’s critically imperiled sand prairies; summer harks the appearance of the diminutive and almost-impossible-to-see Ant-like Tiger Beetle (Cylindera cursitans) in the ribbons of wet bottomland forest that line the Mississippi River; autumn is graced by the sight of stunningly beautiful amorpha borers (Megacyllene decora) in wet areas hosting mixed stands of false indigo (Amorpha fruticosa) and goldenrod (Solidago spp.); and all season long a variety of seldom-seen insects (e.g., longhorned beetles that look like stag beetles) are attracted to ultraviolet lights set up in the area’s increasingly scarce natural habitats.

Hairy mallow (Hibiscus lasiocarpus), host for Agrilus concinnus

Hairy mallow (Hibiscus lasiocarpus), host for Agrilus concinnus

Another phenological event that I look forward to in the southeastern lowlands is the blooming period of hairy mallow (Hibiscus lasiocarpus). Starting in July and reaching its peak in early to mid-August, the enormous white (and sometimes pink) flowers explode across the landscape at a time when precious few other flowers can be found, conspicuously flagging any ground where water tends to stand. It is not the flowers themselves, however, that pique my interest, but rather a beautiful (and, until recently, rare) jewel beetle (family Buprestidae)—Agrilus concinnus—that becomes active on the plants while they are in flower. In fact, of the nearly 200 species belonging to the genus in North America, I consider A. concinnus to be perhaps the most beautiful!

Agrilus concinnus | Stoddard Co., Missouri

Agrilus concinnus | Stoddard Co., Missouri

I first saw this species in Missouri’s southeastern lowlands nearly 30 years ago. At that time, I didn’t know that the mating pair that I had found on low vegetation represented a species considered to be one of the rarest of the genus in North America (having been recorded only from Florida, Georgia, Illinois, and Texas and not yet known from Missouri) and whose host plant and biology were completely unknown. Over the course of several years following this first find, fellow buprestophile Gayle Nelson (now deceased) and I were able to document the occurrence of this species also in Kansas (MacRae & Nelson 2003) and confirm its association with plants in the genus Hibiscus (MacRae 2006). We also determined that adults of this species exhibited an unusually late seasonal occurrence, peaking in late July and early August, compared to the spring adult activity period of most other eastern North American species in the genus. As a result of these efforts, one of North America’s rarest and least known jewel beetles was no longer regarded as either. A more detailed summary of my experiences with this beetle can be found in a newsletter article that I wrote a while back (MacRae 2004).

Hibiscus lasiocarpus

Plants in peak bloom signals the adult activity period of the beetle.

Of course, those were the days before I began photographing insects, so despite the abundance with which I have seen this species in past years, I still lacked photographs of it. I first made an effort to photograph adults two years ago while on one of my research plot trips, but 2012 was characterized by a severe drought in the central U.S.—precious few potential host plants were found at the locality where I first collected these beetles, and those that were present were severely stunted and in poor shape due to the drought. Conditions were much more favorable last year (2013), but again no beetles were seen during an early August visit. This past season was again favorable for growth of the host plants, and though my visit during early August again looked like it was not going to pay off, I eventually scared up an adult and watched it as it flew to another plant. I would see four adults on the day—not a lot, but enough to make sure that I got photographs showing how spectacularly beautiful they are!

Agrilus concinnus

Adults perch, mate, and feed on the upper leaf surfaces.

REFERENCES:

MacRae, T. C. 2004. Beetle bits: Hunting the elusive “hibiscus jewel beetle”. Nature Notes, Journal of the Webster Groves Nature Study Society 76(5):4–5 [pdf].

MacRae, T. C. 2006. Distributional and biological notes on North American Buprestidae (Coleoptera), with comments on variation in Anthaxia (Haplanthaxia)viridicornis (Say) and A. (H.) viridfrons Gory. The Pan-Pacific Entomologist 82(2):166–199 [pdf].

MacRae, T. C. & G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70 [pdf].

© Ted C. MacRae 2014

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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6 Responses to North America’s Most Beautiful Agrilus Jewel Beetle

  1. Reblogged this on agrikeralam and commented:
    lovely

  2. James C. Trager says:

    Every time you write about a beetle associated with a plant we have in abundance at SNR, I get longings for a beetle expert to do some serious survey work here. Do you know such an expert who might be interested?🙂

    • I searched the mallow plants at SNR shortly after confirming the association of this species with that plant. I did find another jewel beetle associated with mallow (Paragrilus tenuis) but did not see A. concinnus. I’ve searched larger stands of mallow in Route 66 State Park as well, also without success. So far we have only found this beetle in long-term natural stands of the plant.

  3. el1a5 says:

    Reblogged this on diretormachado20111 and commented:
    Ramos de Ebisco em plantas trepadeiras.

  4. Joshua Basham says:

    I think that has been my problem with finding this species here in my area of TN. Seems like all the mallow I find usually gets mowed at some point during the fall. I’m bet a good trip to western TN would yield specimens.

    • I checked some mallow in western KY just north of the TN border the day before I found these guys at the spot in Missouri. I’ve also checked lots of other mallow stands in Missouri and have not seen this species on any of the stands that are not in natural areas. I suspect they aren’t fond of disturbance by mowing or maybe even stands that are fairly recent in their establishment. Got any lowland natural areas in western TN?

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