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The Not-so-sacred Scarab

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by Michael P.T. Gillett

(This article appeared in the October 1992 issue of the Newsletter.)

When I first came to Al Ain for an interview visit, I asked someone connected with the ENHG about beetles. "Never seen any," they said. "Oh! Except for the sacred scarabs out in the desert." Well, having been here myself for nine months, I am afraid that I have to disagree on both points. The UAE has a magnificent beetle fauna, but there just ain’t no sacred scarabs!

I have examined several hundred of scarab beetles from around the region and I have to say that all of these have keyed out to Scarabeus cristatus F. and not S. sacer L. or the closely related S. gangeticus Cast.. The salient features of S. cristatus include possession of a median sharp tooth on the forehead (lacking in the other two), thick red hair on the legs and smaller size. Of course, this is not to say that it is S.sacer alone which is depicted in the ancient Egyptian tomb paintings (since all three spp. are similar and all occur in Egypt). It is just that the Latin name was affixed to the only one of the three which occurs in southern Europe. Some quite different scarabaeid beetles were also portrayed on ancient Egyptian artefacts and these can be identified as belonging to the genera Hypselogenia, Copris, Catharsius and Gymnopleurus. Of these, the last two are represented in the U.A.E. by at least a brace of species each (although these have yet to be determined). There are also many other smaller species belonging to the genera Onitis, Cheironitis, Onticellis and Onthophagus amongst others. The massive Heliocopris gigas, also belongs to this family (Scarabaedidae) and is one of the largest Arabian beetles, but it has yet to be found by me.

Of the beetles mentioned, only Scarabeus and Gymnopleurus are "ball rollers", but there are other genera in neighboring countries (Mnematium, Anomiopsis, Eueranium etc.). An interesting feature of all except Gymnopleurus, is the absence of tarsi from the front legs. This modification is an adaptation to the ball-rolling habit and is shared by many neotropical species of dung beetle (e.g. Phaneus from Brazil). If you have ever had the opportunity to watch the activity of these beetles, you will know that, not only is it interesting and at times downright funny for the observer, but it is also a serious business for the scarab(s) involved. S. cristatus is mainly nocturnal, but can be found in the late afternoons during spring rolling balls made generally from camel dung. The balls are not the actual faecal pellets of camels but rather are re-constructed from chopped-up dung (the shapr teeth on the front of the head and front tibiae are used for this). The balls are perfectly spherical and vary in size from less than 2.5 to more than 4.5 cm diameter and are constructed for two different purposes. Smaller balls, seen being propelled around by a single beetle, are often just for the feeding requirements of that one adult. Large balls are sometimes manouvered by a pair of beetles, but usually only by a single female, and are intended for reproductive purposes. During the transporting process, there is always the possibility that other scarabs will attempt to dispossess the original owner. Fights take place and, I am glad to say, it is usually the owner who wins. Using the height of the ball as an advantage by gripping it with the middle and rear legs the owner uses the powerful front legs to topple and even invert the assailant. Whilst I have not seen this behaviour with S. cristatus, I have watched it many times with S. semipunctatus F. in Italy.

If you are lucky enough to come across S. cristatus in the action of rolling a ball and you have a few minutes to spare, it is really quite good fun to follow and watch what happens. The ball is propelled backwards by the beetle whose sense of direction does not appear to be too crucial to the proceedings. At any rate, going round in big circles and up and down the same sand dune seems to be part of the plan – perhaps a devilishly fiendish one intended to throw off pursuit by the erstwhile ball rollers! The funniest moments (for the observer) are when half-way up a slope, control is lost and the ball, with the beetle still clinging to it, gathers momentum and crashes down to the bottom again --- rather like a scene from Tom & Jerry! However, our scarab is nothing if not determined; a second attempt is quickly made, and usually proves successful. Eventually, after 50 or even 250 metres of up-dune and down-dune, the ball is brought to rest (usually on a gently sloping patch of firm, bare sand) and the driver jumps down. Sand begins to fly in all directions and within about half a minute the ball is superficially buried. The scarab next begins to dig a horizontal tunnel away from the buried ball. At this stage, there are frequent comings and goings at the entrance to the burrow as the spoil is removed (and generally left on top of the buried ball!). After about five minutes, the scarab emerges and then, with something akin to the panic shown by a woman who has lost her handbag, a frantic search for the buried ball begins. Antennae are flared! Trial excavations made here and there! Eventually, however, the buried prize is recovered and then speedily thrust backwards into the burrow, which is then sealed.

This would appear to be the end of this little saga and the scarab should now be able to look forward to a bit of peace and quiet. However, rarely do things go so smoothly in nature. Our hero, secure within his tunnel, is not quite as alone as he or we might think. Firstly, even before the ball was first rolled away from its construction site, a number of parasitic scuttle flies will have sought out the scarab and attached themselves like glue to its elytra (wingcases). During all the subsequent manouvering, including the crashes and the tunnelling, these flies do not budge. However, within the darkness and relatively humid surroundings of the tunnel, they will mate and lay eggs within the beetle’s body. These will hatch into tiny maggots which will eat away at the living beetle, growing and eventually dropping off to pupate within the sand. A second group of unwanted guests were brought into the tunnel inside the ball. These are smaller dung beetles of the genus Aphodius, the cuckoos of the coprophagous world. How and why these relatively active beetles contrive to get themselves incorporated into the scarab’s ball is not well understood. Probably, the original habitat of these little beetles was in surface dung but, since this dries very quickly in the Arabian climate, by hopping into the scarab’s private supply they may gain the advantage of a less quickly-drying food source, but without the hard work of buying it for themselves. Some species of this genus in UK are true cuckoo parasites in the breeding chambers of dor beetles (Geotrupes).

As already mentioned, the larger balls rolled away by scarabs are used to provide food for larval development and are not eaten by the adults. The ball is buried, as before, but probably to a greater depth. The female then cuts the ball up into small pieces and remakes it into a pear-shaped mass, in the top of which a single egg is laid. The mass will provide sufficient food for the whole of the life period of the fat white ‘C’-shaped grub. Each female scarab lays only about six eggs, each in a separate brood ball. This small number of offspring for beetles such as S. cristatus which provide specialized brood care is to be contrasted with the tens of thousands of eggs laid opportunistically be female oil beetles, about which a future article is planned.


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