The Churchyard Beetle (Blaps gigas, Ħanfusa tal-kantina) is one of the largest beetles inhabiting the Maltese islands. Most individual specimens can grow up to 35mm long but the largest specimens recorded on isolated islets such as Selmunett were 41mm long. It prefers to live in dark humid areas and can sometimes be found in basements, cellars, cave entrances and obviously churches, hence its common name.
The latter species belongs to a family of beetles known as Tenobrionidae (the darkling beetles). Their generic name is derived from the dark colour of their exoskeleton. This is a large family with more than 20,000 known species worldwide. Locally 61 species of this family of beetles can be found, of which a number of them are endemic to the Maltese islands.
The front wings of most beetles are hardened and cover the abdomen and a pair of delicate wings underneath them. To fly, most beetles lift their front wings and unfurl the hind wings. The churchyard beetle cannot fly because its front wings are fused together and cannot be lifted.
It seems this was not always the case as studies by the authors from an anatomical aspect show that this species once had wings that enabled it ancestors to take flight. The same goes for the flightless Great Ground Beetle (Carabus morbillosus alternans, Bunittien). Studies by the same authors show that the latter species actually still retains tiny developed under-wings.
In evolution, species tend to become flightless due to lack of predators in their new colonised land, and because flight itself is an expensive commodity energy-wise. The ancestors of this beetle might have been smaller when they still had flight, so it makes sense that the beetle grew in size. Being large also makes it harder to regain flight.
While the species are classified as frequent rather than common, it tends to have quite a vast distribution, and the authors managed to find this species almost on every Mediterranean island and islet they visited that is habitable to terrestrial species. This is of utmost interest as the latter is a flightless species so it could only have reached such sites by drifting on some material that landed on the island or it was isolated during the period of the islet formation itself.
This casual intruder should be regarded as a beneficial species because they usually eliminate and decompose decaying material
Each island or islet has its own micro habitat, and species like lizards or snails and several flora that easily differ through time, at least in appearance, from their ancestral population, some of which are classified as different population or even a completely separate species.
Regarding this particular species, the authors, along with Pietro lo Casio, collected data of all the populations found on all the Maltese islands and islets (18 in total) and most Italian and Sicilian islets. Besides their variability in size, which can be attributed to number of factors, there is hardly any significant difference between each population from the mainland ones.
Although most naturalists love to discover and publish new species, such findings are usually discarded. However, we were surprised and further investigated how such a flightless species was found trapped in such isolated and different habitats, when it seems no noticeable natural selection was taking place.
The authors carried out morphological (appearance) studies, and molecular (DNA) testing would one day reveal more surprises. A similar situation was noted in a higher ranking species, the Turkish gecko (Hemidactylus turcicus) which is also found on every Maltese islet, and each population is almost morphologically identical.
Many people locally seek professional pest control advice when encountering this species in their residence as they are concerned at having such a large insect wandering around their premises. Some even call it regina tal-wirdien (queen of the cockroaches) as they associate it with common pests such the American cockroach. In reality, these species are not related.
This casual intruder should be regarded as a beneficial species because they usually eliminate and decompose decaying material. Not only is this insect very interesting to observe from a behavioural aspect, but if undisturbed, it does not scare easily. It usually continues its daily routine in front of the observer, making it much easier to collect data on it than most species.
Disturbing a Churchyard Beetle will result in a change in its posture to make it appear larger, but if that is not enough to deter the intruder or predator, it secretes a pungent liquid from glands that are found in the joints of its limbs that is not easy to get rid of, which is also a characteristic defence mechanism belonging to the Great Ground Beetle.
Arnold Sciberras is an entomological pest consultant and Jeffrey Sciberras is a botanical pest consultant at Fort Pest Control. For further information call 2143 4534 or e-mail info@fortpestcontrol.com.