Paragrilus tenuis (LeConte) | Stoddard Co., Missouri
This past summer I visited Otter Slough Conservation Area in southeast Missouri in an effort to find and photograph the stunningly beautiful Agrilus concinnus Horn, or “hibiscus jewel beetle” (MacRae 2004). I was not successful in that quest, but I did manage to snap a single photo of another jewel beetle also associated exclusively with hibiscus, Paragrilus tenuis (LeConte). This species belongs to a much smaller genus of mostly Neotropical jewel beetles that resemble the related and much more speciose genus Agrilus but differ significantly by their antennae being received in grooves along the sides of the pronotum and, for the most part, their association as larvae with stems of living, herbaceous plants rather than dead branches and twigs of deciduous trees. Only four species of Paragrilus occur in the U.S. (Hespenheide 2002), and of these only P. tenuis is known to occur in the eastern U.S. where it has been reported breeding in Hibiscus moscheutos (including ssp. lasiocarpos). I have also collected adults on H. laevis (MacRae 2006), but to my knowledge it has not yet been reared from that plant.
These tiny little beetles (~ 5 mm in length) are normally seen resting on the terminal leaves of their host plants, but they are extremely wary and quick to take flight. As a result, photographing them in situ with a short macro lens in the heat of the day is rather challenging, especially when they are not numerous. I only saw perhaps half a dozen individuals during the visit, and the photo shown here represents the only shot that I even managed to fire off. While I would have liked to have gotten a dorsal view of the beetle, this single shot is nevertheless well-focused and a rather interesting composition.
REFERENCES:
Hespenheide, H. A. 2002. A review of North and Central American Paragrilus Saunders, 1871 (Coleoptera: Buprestidae: Agrilinae). Zootaxa 43:1–28 [pdf].
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].
Copyright © Ted C. MacRae 2013
Beetles In The Bush 
Cool beetle. Any idea how far north it ranges?
Reported distribution is New York south to Florida and west to Missouri and Mississippi. Find hibiscus during spring and early summer and you should be able to find the adults. I will say that I’ve only seen it on native hibiscus in natural habitats and never on cultivated plants.
We have a lot of Hibiscus in our yard, but I think it is a cultivated variety. I’ll have to check for it on H. moscheutos next year. Thanks for the info.
Ted – You really have intrigued me with the jewel beetle aspect (long-horns, too) of biodiversity through your various posts on them. It has stimulated what I would describe as an ordinate fondness.
One thing: “antennae being received in grooves” — Do you mean recessed?
Glad to hear that, James! Generating interest is a key purpose of this blog!
I’m not sure “recessed” is the best word to use here, as it implies (to me) that the antennae are normally situated within the grooves. Instead, in their normal position they are held free and received within the grooves only during defensive tucks. We can quibble about it.
p.s. I believe I have seen this species on hibiscus at Shaw Nature Reserve.
This bugguide link shows the antennal grooves well:
http://bugguide.net/node/view/373282
Nice view of one of the grooves (sulci :)).