Mercarto flies (a human rendering of the Styrásh már'cár'tó or már'cár'tó - a direct translation is difficult but indicates that these waterliving incects are takers of elven life) is actually something of a misnomer, as they are in fact carnivourous flying beetles, sucking blood from other animals. The Shendar of southern Sarvonia know them as "Tra'mat". Normally native only on the Narfost Plain, they are killed off annually after mating and laying eggs by the cold of winter. However, if the climate further north is favourable they have, on occasion, migrated as far north as New-Santhala. The beetles are now known, thanks to a series of elegant experiments in the last ten years to carry a pathogen, lethal to elves in the more northerly forests, while elves of the Sharadon seem to have an innate resistance. In humans the pathogen seems only to produce mild vomiting for several days.

Appearance. When in flight these beetles appear to be flies, with their small wing cases tucked in and hidden from view, and their long projected legs. However, upon landing it is clear that Mecarto flies are most definetly beetles. They are quite unremarkable to look at, about the size of a man's fingernail, with black wing casings. What makes them easy to identify is their long legs, unusual for a beetle.

Special Abilities. But do not let their overall appearance fool you. For closer examination identifies them as uniquely dapted to the harsh life on the arid plains. Detailed analysis by the human Scientist Camen Prelvin, based at Marcogg, showed that as invertbrates with little cirulatory system, the beetles must conserve water, as such the excretion system is brilliantly setup to prevent water loss, as water is reabsorbed, therefore toxins are - if necessary - excreted as dry pellets. Respiration is also heavily regulated, spirochets on the legs of the beetle can be opened at night to take in oxygen, and closed to the heat of the day to prevent evaporation.

Prevlin also undertook a detailed study of the mouth parts of the beetles and showed the normal mandibles have undergone intense adaptation as a result of their diet. To suck the blood of other animals, their mouth parts have become much elongated with, a sharp point to allow penetration of the the animal's skin. Prevlins original sketches and observations are reproduced below.

Territory. Normally isolated on the arid Narfost Plains, though they have been found further north if climatic conditions that year allow it.

Habitat/Behaviour. Larvas hatch underground and must tunnel their way to the surface. This is done using the larval mouthparts. For the first few days of life, the larva must live underwater, thus hatching occurs in spring after the heavy rainfalls. The larva then pupate on the surface after three days in a floating casing known as a loit. At this stage they are very vulnerable to being eaten by other animals and birds. As such one beetle produces millions of eggs, only a few hundred at most will reach maturity.

After puption, the insects climb onto their loit and fly away. Much of the rest of their life is spent on the wing, landing only to feed and to lay eggs.The eggs must be laid in an area where there will be water next year, hence eggs are laid underground, observation suggests often in the exact same position as the beetles own place of birth.

The beetles are killed off by the cold of the winter. Hence there is a new generation every year.

Diet. Marcarto Flies have adapted to suck the blood of animals. They are not fussy eaters, equally at home sucking the blood of aj‘nuvic, humans, and perhaps prefer them as human skin is less thick, and there is little fur to penetrate. Blood is an ideal food for these flies, few other food sources provide such an easily absorbed source of water and nutrients.

Mating. Mating is a very simple process. The female lays here eggs in an underground tunnel that she has dug, using paddle like front legs. Males find these tunnels and fertilise the eggs, many males may fertilise the same batch of eggs.

The Sickness. These beetles have recently identified to carry a pathogen that is fatal to elves, though those living in the Sharadon forests seem to have an innate resistance. The nature of this pathogen is as yet unclear, though what is clear from Prevlin's experiments is that the pathogen is both carried within the beetle and released into water in which the beetles pupate in.

The Mercartos are not often found underground and so do not present a large hazard to the dwarven race; however, the Thergerim do have a reaction to the pathogen and a name for the beetles. "MarGruterons" (MarGruterons) translates as "Blood-Biters". Something in the saliva of the insect reacts poorly with Thergerim blood, causing it to not coagulate properly, and the sufferer generally dies of an acute hemophiliac reaction.

In the normal climate this pathogen is probably kept in check by natural predators of the the insects, especially during the larva and pupa stages. They are also killed off by the cold of the winter on the Narfost Plains. When climatic conditions are extreme the beetles may move northward. The most devestating case of this was during the third great flood, when warm weather and the intense rains previously provided ideal conditions for them to move as far as the Zeiphyr and the Quallian. Here their natural predators did not exist, and the warmer wetter winter meant that they were not killed off annually, as is normally the case. Thus the flies multiplied in great numbers, though this in itself was not a huge problem. The problem was that they carried with them their pathogen, the nature of which is not yet clear, which in the stagnent flood waters lingered in the water supply for many years. This is what earned the flies their elven title as the water life takers. The Sickness killed many members of both the emerging Ylfferhim and the Quaelhoirhim. However, the flies were eventually controlled by a return to normal climate.