LEPROSY is a specific, infectious disease due to _Bacillus lepræ_, and characterized by the formation of tubercular nodules, ulcerations, and disturbances of sensation. In spite of the long time that the disease has been known and the dread with which it is regarded, little is known concerning the method of transfer of the causative organism or the means by which it gains access to the human body. It is known that the bacilli are to be found in the tubercles, the scurf of the skin, nasal secretions, the sputum and, in fact in practically all the discharges of the leper. Under such conditions it is quite conceivable that they may be transferred in some instances from diseased to healthy individuals through the agency of insects and other arthropods. Many attempts have been made to demonstrate this method of spread of the disease, but with little success. Of the suggested insect carriers none seem to meet the conditions better than mosquitoes, and there are many suggestions in literature that these insects play an important rôle in the transmission of leprosy. The literature has been reviewed and important experimental evidence presented by Currie (1910). He found that mosquitoes feeding, under natural conditions, upon cases of nodular leprosy so rarely, if ever, imbibe the lepra bacillus that they cannot be regarded as one of the ordinary means of transference of this bacillus from lepers to the skin of healthy persons. He believes that the reason that mosquitoes that have fed on lepers do not contain the lepra bacillus is that when these insects feed they insert their proboscis directly into a blood vessel and thus obtain bacilli-free blood, unmixed with lymph.