Prospekt Fauna, Intresting facts

Photo 1. The beetle Lygaeus saxatilis on the blossom of a crocus-leaved romulea (Photo by Patrik Krstinić)

Near the long-lived, giant downy oak in the region of Dolinji Drmun Puški above Čavlena Cove, the crocus-leaved romulea (Romulea bulbocodium) (Photo 1), the early-gold crocus (Crocus reticulatus) (Photo 2) and several other species of early flowers began to blossom at the very beginning of this year (in January and February), painting the still dormant and bleak grassland with unusually lively colours. These flowers are scattered, here and there, across the sparse grasslands and in the encroaching barren underbrush. The few insects that awake early from hibernation at this time of year and leave their shelters seem to know exactly where to go. The crocus-leaved romulea with its star-shaped, yellow-centred purple flowers attracts insects like a magnet. One of its most devoted visitors is the beetle Lygaeus saxatilis, a brightly and conspicuously red-and-black coloured insect (Photo 1). While L. Saxatilis is diligently exploring the centre part of flowers with its proboscis and probably sucking nectar and other plant juices from the first early-spring flowers, its relatives of the species Lygaeus sp. (Photo 3) in the neighbouring habitat prefer to stay close to their shelter in the cracked bark of an old tree. They can usually be found basking in the winter sun in smaller or larger groups.

Beetles of the genus Lygaeus are noted for their ability to feed on the juices of some very poisonous plant species, their favourite being plants of the genus Vincetoxicum sp. div (swallow-worts). By sucking on the juices of these plants, the beetles accumulate poisonous components in their bodies which protect them from potential predators. The red and black patterns on the bodies of these insects “advertise”  their inedibility.

On the mainland, L. Saxatilis is a very common species. In the early (pre-) spring, as soon as the snow has melted, these beetles can be found basking in the sun among dry, fallen leaves. Later they will disperse, each individual going its separate way. Up to date, we had not noted such aggregation behaviour in L. Saxatilis on Krk Island. We have to ask ourselves whether they have begun to follow the habits of their mainland relatives or have they developed some other life strategies that compel them to disperse, each in its own direction, in search of the food sources provided by early-spring flowers?

Marko Randić and Patrik Krstinić

Topics: Interesting facts about nature, about plant life, about insects

Keywords: beetles, Lygaeus, spring flowers, crocus-leaved romulea, Romulea bulbocodium, Krk Island,  Čavlena Cove

Link to “Priroda” Web page: http://www.ju-priroda.hr/zanimljivosti.asp?iddb=94

Photo 2. An early-gold crocus (Crocus reticulatus) near Čavlena Cove on Krk Island (Photo by Patrik Krstinić)

Photo 3. A group of beetles (Lygaeus sp.), basking in the winter sun in the cracked bark of a tree. (Photo by Patrik Krstinić)