176 BLACK-FLIES. 
which flies with great force so that it can be felt when strik- 
ing the face. It seems that it does not care much for human 
blood, but it irritates considerably by being of a very in- 
quisitive nature, even entering mouth, nose, ear and what is 
worse, the eye. If horses are left standing for some time in 
the roads, they are apt to become restive, shake their heads 
in a violent manner, frequently stamping and snorting at 
the same time. If the ears of the horse are inspected we 
usually find the cause of their irritation in a large number of 
such small flies, which are busily engaged in sucking the 

Fig. 144.—Simulium decorum. Female. Greatly enlarged. Original. 
blood, and they do so by inserting their powerful piercing 
organs into a vein, hence they seem to be arranged in regular 
rows. Ifnot occurring in very large numbers they cause but 
little harm, and an application of a little grease rubbed to- 
gether with a few drops of carbolic acid, soon remedies the 
evil, and drives away other intruders. According to 
Coquillett, who kindly determined a number of species of 
this genus for the writer, it is an undescribed species. On 
account of its very small size the name of Simuliwm minutum 
is proposed. The female insect is illustrated in fig. 145; the 
male has not been seen. This species flies from May 15 to 
