Beetle Bites – Nitidulidae: the Sap Loving/Hating Beetles

Niti1

Homepuraea amoena (Photo: S.E. Thorpe)

I like nitidulids; they’re an okay group of critters despite being members of the most confusing and convoluted groups in all of Coleoptera. They’re cute in the same awkward, bumbling way as the totally unrelated heterocerids.

Niti2

Cryptarcha concinna (Photo: Mike Quinn – bugguide.net)

Hetero1

Heterocerus sp. (Photo: Tom Murray – bugguide.net)

See, totally the same.

More strikingly, a few members of the subfamily Cillaeinae resemble tachyporine rove beetles to a preposterous degree. Same with these guys.

conotelus

Conotelus obscurus, a Nitidulid (Photo: Steve Nanz – bugguide.net)

tachyporine

Tachyporus jocosus, a staph (Photo: Mike Quinn – bugguide.net)

Unlike heterocerids, nitidulids are actually kind of important: some are pollinators of human food crops, others are agricultural pests of both live and stored plant products. One species, Glischrochilus quadrisignatus, apparently has a reputation for ruining picnics by suicidally diving into beverages, especially beer, which makes them one of the most strangely heinous beetle pests in existence (I have a crackpot theory that nitidulids are partially responsible for the inexplicable lids found on beer steins). A lot of nities also feed on fungi; next time you’re in the woods, take a peak under the nearest shelf mushroom and I bet you’ll find some of these guys.

Niti3

Glischrochilus quadrisignatus, the bane of picnics everywhere (Photo: Miroslav Deml)

There are species of nitidulids that eat practically everything: pollen, nectar, fruit, leaves. There are even a hand-full of carnivorous species. The one thing they don’t eat is sap. They hate the stuff, so there are no sap-eating species. Nope, not even one. Of course, there are a few that act like they enjoy sap, but it’s all just a clever ruse to fool would-be predators who would never think to look for them in sappy places. I’m onto your game, nitidulids.

In a particularly baffling case of unexpected consequences, an invasive species of nitidulid introduced in the US in the nineties, Aethina tumida, has become a major concern to beekeepers. They look harmless, right?

aethinaadult

Aethina tumida adult (Photo: James D. Ellis)

The adults sure do, but they aren’t the main concern for bee hives: the larva are the real terrors.

aethinalarva

Aethina tumida larva (Photo: James D. Ellis)

Gross.

More crackpot theories: I believe a particularly intrepid nitidulid, hoping to exploit the similarity between sap and honey, decided to take refuge inside a bee hive, only to discover that terrorizing bees was much more entertaining than being chased by predators all the time. If any creative and/or amoral entomologist is interested in coauthoring this paper with me, hit me up at beetlefacts@gmail.com.

If you’re curious about the evolution and systematics of this family, you’ll be happy to learn that they’re fairly well studied. This paper is a good starting point, but there are certainly many others worth looking at.

Notable characteristics: 3-segmented antennal club, transverse procoxal cavities, grooved metacoxa, and dilated tarsomeres (Arnett et al., 2002). Many (but certainly not all) are darkly colored with orange/pale mottling (also true of some Erotylidae).

Diversity: >4,000 species in over 200 genera.

References:

  • Arnett, Ross H., et al., eds. American Beetles: Polyphaga: Scarabaeoidea through Curculionoidea. Vol. 2. CRC Press, 2002.
  • Cline, Andrew R., et al. “Molecular phylogeny of Nitidulidae: assessment of subfamilial and tribal classification and formalization of the family Cybocephalidae (Coleoptera: Cucujoidea).” Systematic Entomology 39.4 (2014): 758-772.

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