102 
Parasitic Arthropoda 
sucking species, notably Culex pipiens, have been bred repeatedly 
without opportunity to feed upon blood. 
The effect of the bite varies greatly with different species and 
depends upon the susceptibility of the individual bitten. Some 
persons are driven almost frantic by the attacks of the pests when 
their companions seem almost unconscious of any inconvenience.. 
Usually, irritation and some degree of inflammation appear shortly 
following the bite. Not infrequently a hardened wheal or even a. 
nodule forms, and sometimes scratching leads to secondary infection 
and serious results. 
The source of the poison is usually supposed to be the salivary 
glands of the insect. As we have already pointed out, (p. 34) r 
Macloskie believed that one lobe of the gland, on each side, was; 
specialized for forming the poison, while a radically different view is. 
that of Schaudinn, who believed that the irritation is due to the- 
expelled contents of the oesophageal diverticula, which contain a. 
gas and a peculiar type of fungi or bacteria. In numerous attempts, 
Schaudinn was unable to produce any irritation by applying the 
triturated salivary glands to a wound, but obtained the typical result, 
when he used the isolated diverticula. 
The irritation of the bite may be relieved to some extent by using 
ammonia water, a one per cent, alcoholic solution of menthol, or 
preparations of cresol, or carbolic acid. Dr. Howard recommends 
rubbing the bite gently with a piece of moist toilet soap. Castellani 
and Chalmers recommend cleansing inflamed bites with one in forty 
carbolic lotion, followed by dressing with boracic ointment. Of 
course, scratching should be avoided as much as possible. 
Repellents of various kinds are used, for warding off the attacks 
of the insects. We have often used a mixture of equal parts of oil 
of pennyroyal and kerosene, applied to the hands and face. Oil of 
citronella is much used and is less objectionable to some persons. A 
recommended formula is, oil of citronella one ounce, spirits of camphor 
one ounce, oil of cedar one-half ounce. A last resort would seem to- 
be the following mixture recommended by Howard, Dyar, and Knab 
for use by hunters and fishermen in badly infested regions, against 
mosquitoes and blackflies. 
Take 2]/^ lbs. of mutton tallow and strain it. While still hot add 
]/2 lb. black tar (Canadian tar). Stir thoroughly and pour into the- 
receptacle in which it is to be contained. When nearly cool stir in 
three ounces of oil of citronella and 1)4 oz. of pennyroyal. 
