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The elusive tiger beetles of Ain al Fayda


by Michael P.T. Gillett

(The following appeared in the Al Ain Newsletter of September 1992)

Although they have often been regarded as constituting a separate family (Cicindelidae) within the suborder Adephaga, tiger beetles are now more usually given supertribe status and signed, as the Cicindelitae, to the enormous family of ground beetles (Carabidae). The reasons for this need not concern us but it is of interest to note that there are five separate tribes of tiger beetles whose members have widely different characteristics; only two of these, the Cicindelini and the Megacephalini, are likely to occur in Arabia. the three other tribes are the neotropical Ctenostomatini, the oriental Collyrini (two groups of arboreal beetles which live high up in the forest canopy where they lead a predatory existence running effortlessly over leaves and along twigs as they seek their prey: many species resemble ants and have no powers of flight) and the African Mantichorini (giant and exceptionally fierce ground-living species confined to the southern African deserts). The world wide genus Cicindela constitutes the bulk of the tribe Cicindelini and will be familiar to some readers as these beetles are diurnal, sun-loving species, often with striking metallic coloration and delicate markings. They frequent sandy heaths, open woodland, river banks and beaches but, because they rapidly take to the wing, they are often difficult to observe at close quarters. The tribe Megacephalini contains flightless beetles, which are terrestrial and nocturnal in their habits. There is but one genus, Megacephala, appropriately named for their large head with its powerful mandibles. Most species are similar in appearance, having metallic green bodies with golden, bronze, purple, blue or blackish overtones and the tops of the elytra (wing cases) are not pigmented.

Tiger beetles – the name comes either from the striped appearance of some well known European and N. American species of Cicidela or because of their fierce predatory behavior – are definitely uncommon in the Al Ain area. In September, 1991, I saw one example from the Cicindelini near the mosque at Ain al Fayda. The beetles was very active when approached, taking easily to flight and then alighting some distance away. Although I tracked it for over five minutes, it eventually got bored with my game and disappeared before I could make a tentative identification of the genus (Cicindela or Myriochile?). Some two months later in November I was again at Ain al Fayda and decided to make an attempt to find the breeding site(s) for these tiger beetles. Terrestrial tiger beetles lay their eggs individually in firm sandy soil and the larva makes a vertical tunnel with an open top. The burrows are usually found in groups of a dozen or so and any small creature approaching the lips of the hold is firmly grasped by the larva’s mandibles and pulled underground where it is quickly consumed; ants are a favorite prey species. The burrows are flush with the surface of the soil and have no piles of excavated soil nearby which makes it easy to distinguish them from ant-lion pits and ant nests.

Near the old bathing house at Ain al Fayda, I discovered several patches of ground with tiger beetle holes and thought that I had found the breeding sites of the beetle that I have already mentioned. However, on scratching around near one group of holes I came upon a perfectly preserved adult head capsule (8 x 6 mm) from a quite different species of tiger beetle. Without doubt, the remains I had found were from a species of Megacephala. Having lived for many years in Brazil, I am quite familiar with the genus which is well represented in S. America with many species inhabiting the rain forest, the caatingas of the NE region and even the gardens of houses in Rio, Fortaleza and Recife. It was quite a shock to realize that here in the UAE was a beetle so very closely related to ones that I know from this neo-tropical fauna. A little research revealed that Megacephala zoogeography is the stuff on which continental drift theories draw support! South America is indeed the headquarters of the group, but there are a number of species in Africa and at least one in Australia (M. australis) (all very similar in both appearance and habits). Two species have radiated away from the remains of the ancient landmass of Gondwanaland and are found in the USA (M. carolina) and in S. Europe (M. euphratica).

This latter species is most probably the one occurring at Ain al Fayda, since it is known to range from Spain, Cyprus, across N. Africa to the Sinai, Syria, the Caucasus and into Iran and Afghanistan. The beetle is an attractive one, having metallic green/purple coloration, but a blue form (var. armeniaca) is known from the northern range of the species. The head capsule that I found would indicate that it is the green form that occurs in the UAE but I have yet to see the living beetle. The beetle has always been noted as occurring near to fresh water, a fact that fits the Ain al Fayda location. I have returned periodically to the breeding site; the holes remain open and have been enlarged so that, at the time of writing, the pupal stage has not yet been reached. I am even a little anxious that I might miss the emergence of the adult beetles during the long summer leave! Meanwhile I have still to locate the breeding sites of the Cicindelini species which prompted the present discovery.

The above account was written in April and requires updating, as it is now early June. Since I wrote, the tiger beetle site has suffered a series of man-made disturbances. Firstly, there has been a widespread fire over the area, which has removed the reeds and other vegetation, and secondly there has been serious flooding caused by overflow from the falaj. On a recent visit, I was amazed to find that many of the burrows are still there and continue to contain active larvae, despite their being surrounded by a thick crust of salt. Truly an incredible feat of survival! I do not now expect to see the adult beetles until later on in the year. However, on the same visit, in nearby sand dunes, I was able to capture, with some difficulty, a third species of tiger beetle, much smaller than the other two. This is a species of Cicindela, about 10mm long and colored off-white with metallic green-brown markings; it has obvious affinities with a number of species known from Iran, but I have yet to make a proper identification.

Patron: H.E. Sheikh Nahayan bin Mubarak Al Nahayan