196 



contact with the water. This drinking takes place chiefly during the 

 heat of the day, but a number of insects, mostly females, were observed 

 to come to such pools after 3 or 4 p.m. The author therefore recom- 

 mends pouring some liquid on the surface of the pools, which would 

 cling to the underside of the body at the moment w^hen it comes in 

 contact with the water. Very good results were obtained by the use 

 of kerosene ; on the third day after the kerosene has been applied, 

 the whole pool was covered with bodies of dead insects, while those 

 which managed to escape from the pool perished, owing to the kerosene 

 adhering to their bodies and thus poisoning or suffocating them. The 

 kerosene must form a coating over the whole surface of the pool and 

 must be renewed from time to time, if possible, daily. These trap 

 pools are very effective means of destroying the flies and every pool 

 which attracts the insects should be thus treated. Only pools of 

 stagnant water can be utiHsed for this purpose ; they may be artificially 

 constructed and even troughs or any wide-mouthed vessels filled with 

 water and kerosene can be successfully used. Mazute (naphtha 

 residues) proved even more effective than kerosene, owdng to it being 

 cheaper and thicker and thus remaining longer on the water and 

 trapping more effectively. Only individuals of the genera Tabanvs 

 and Chri/sops were trapped in these pools ; Haematopota do not need 

 water and cannot be destroyed by this means. The following species 

 were found in the pools : Tabaniis hovinus, T. montanns, T. tropicus, 

 T. luridus, T. solstitialis, T. borealis, T. macidicornis, Chrysops relicins 

 and C. coecutiens. During five days in one trap pool, of an area of one 

 square metre, in a moderately infested locality, 916 males and 186 

 females of T. montanus, 344 males and 72 females of T. macidicornis, 

 and 416 males and 33 females of Chrysops were captured. The flies 

 appear to need w^ater during the whole of their life and visit the pools 

 whether they have just sucked blood or not. It is suggested that such 

 trap pools should be constructed in pastures for cattle, etc., but always 

 securely fenced against them. Haematopota j^luvialis is the commonest 

 species of the genus in North Kussia. These insects are less active 

 and avoid open spaces, which is attributed to the number of enemies 

 which prey upon them, such as various dragon flies {LibeJhda, and 

 especially Aeschna). They are attracted by black surfaces and avoid 

 white ones. When dressed in white, the author was always less subject 

 to their attacks, as are also whi^ie animals. To reduce their number 

 the use of a black shield, covei'ed with some sticky material and 

 carried on a stick along paths which the flies frequent, is advised ; 

 the men who carry the shield should be dressed in M'hite. The author 

 thinks that, with this remedy, it is possible to destroy all the flies in 

 a given locality ; in one of his experiments, when he used this shield 

 over a distance of about 400 yards along the outskirts of a wood, 

 he captured 283 individuals ; this number dropped the next day to 

 90 at noon and to 28 in the afternoon. Besides all the females of 

 Haematapota thus destroyed, a large number of other flies, such as 

 Hydrotaea meteorica, etc., were also caught. The lid or bottom of a 

 large basket, painted black, makes the best shield. Cardboard, lined 

 with blue paper, may be substituted. The shields may also be used 

 to protect animals directly, by being fixed to the yokes of oxen, etc. 

 The adhesive substance used, consisted of equal quantities of castor 

 oil and resin, heated on a fire. 



