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Insect: Scarab Beetles

Find, identify & discuss the insects of SANParks
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arks
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Insect: Scarab Beetles

Unread post by arks » Mon Dec 13, 2010 3:24 am

Cam anyone help with an ID for this beetle? Seen in the Waylands Wildflower Reserve in Darling on 27 September 2010.

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Jon Richfield
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Re: Insect ID needed

Unread post by Jon Richfield » Mon Dec 13, 2010 4:36 pm

arks wrote:Cam anyone help with an ID for this beetle? Seen in the Waylands Wildflower Reserve in Darling on 27 September 2010.


Arks, the easy part is very easy. It is a monkey beetle. Monkey beetles are seen as members of the scarab family, the Scarabaeidae. (I will not go into the discussion of whether it should be the superfamily Scarabaeoidea). After that things become confusing they also are members of either the subfamily Melolonthinae or Rutelinae, or Hopliinae. The common option at the time of writing this as far as I can tell is the tribe Hopliini of the subfamily Rutelinae.
Take your pick; I don't care. What matters more is that the ones that I know by sight are unmistakable as a group, with their blocky appearance, their general hairiness, which usually is full of pollen, and especially their exaggerated, muscular hind legs. One feature that the taxonomists set great store by is the fact that the last segment of their feet (the tarsi) though they have two well-defined claws like most beetles, only more so, have one claw significantly larger than the other.
Suit yourself about whether you find that interesting, but what certainly matters in finding them in the veld is those hind legs. One almost always finds them on flowers. One usually finds them on vygie or Asteraceous types of flowers, and particularly members of the Asteraceae, such as Ursinias and Gazanias. Exactly what those hind legs are for, is uncertain and disputed. For what it is worth, I suspect that in various species to various degrees they are used for forcing the beetle in among the florets or stamens, hauling them out again when it is time to move, and possibly shoving off other beetles competing for flower space or mates. Again, take your pick.
Some are very plain, some quite beautifully iridescent. I have seen it claimed that they are endemic to southern Africa, but I absolutely disbelieve this; they certainly are very similar looking beetles in parts of Eurasia, America, and I think, Australia. I do not deny that many species (and they really are many!) are endemic to South Africa, but that is another matter.
They are important pollinators, but whether they do more good or harm is a toss up. Some flowers, such as some Gazanias and some Iridaceae, have markings near the centre that are suspected to be adaptations for discouraging monkey beetles, looking as though the flowers are already occupied. This idea is supported by research, but I must admit that I have my reservations.
It certainly is true that they damage the flowers a great deal, but once again, it is not clear to me whether their pollination does more good than their damage does harm.
Either way, they are rather charming members of our fynbos community.

Cheers,
Jon

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arks
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Posts: 3470
Joined: Sun Mar 20, 2005 5:53 pm
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Re: Insect ID needed

Unread post by arks » Mon Dec 13, 2010 5:36 pm

Fascinating stuff, Jon! :thumbs_up: Thank you.
RSA 2016
4,5 April Melville
6-19 April KNP: Croc Bridge, Olifants, Shingwedzi, Pafuri Border
20-24 April Mapungubwe: Leokwe
25 April-28 May Darling
29 May-19 June Cape Town


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