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Beetle with Infestation on Its Elytra - Nicrophorus tomentosus

Beetle with Infestation on Its Elytra - Nicrophorus tomentosus
Upshur County, West Virginia, USA
September 19, 2003
This poor beetle was literally crawling with parasites—mites?

N. tormentosus
Yellow pronotal pubescence and elytral markings place this beetle in tormentosus species.

Thanks, Jim!
Thanks for the species ID, Jim!


Stephen Cresswell
Buckhannon, WV

I have noticed that the mites
I have noticed that the mites often assemble on the elytra, all facing forward, when the beetle is preparing to take wing. the tops of the elytra are turned in toward each other during flight, so the mites are fairly secure from being dislodged should the beetle graze a leaf or twig. The mites get some signal that the beetle is about to fly before it begins its pre-flight fidgets.

Reminds me of another photo

Mites hitchhiking
The mites are "phoretic," meaning they are only using the beetle as transportation. This is a carrion beetle (Nicrophorus sp.), and once it arrives at a carcass, the mites will disembark (de-beetle?), and go about feeding on the eggs of blow flies, the beetle's major competition for the corpse. So, the mites actually benefit the beetle.

Poecilochirus sp.
Stephen Cresswell comments here, "... mites that ride on Nicrophorus beetles are in the genus Poecilochirus".

Very interesting to read about this mite strategy on carrion beetles. They do exactly same with dung beetles.
Apparently when dung beetles were introduced in Australia to tackle the cattle dung, the program was extremely strict as they wanted to introduce only the beetles, nothing else. So they went in the egg stage, sterilized at that. However later on, with the bush fly still a problem to be solved, they wondered "if it had been sensible to exclude from the consignments the mites that abound on the beetles on their native lands".
I've read this recently, see Waterhouse, L.K., 1974. The biological control of dung. Sci. Am., 230:101-109.

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