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.