40 MOSQUITOES OF NORTH AMERICA 
the salivary duct. That Menzbier is incorrect in affirming that the hypopharynx 
has no complete tube I have clearly proved in my observations on Bombylius 
and #ristalis; but the question still remains unsettled whether Culex has any 
passage, either tube or groove, through the hypopharynx. Réaumur * (tome 4, 
part 2, p. 396) discusses the probability of a poisonous fluid being secreted by 
Culez, to cause the blood to flow more readily when it bites, and since his time 
writers have, on the one hand, accepted this statement, without proving the 
presence of such a fluid or of the glands to secrete it, or they have, on the other 
hand, denied the existence of such a fluid and affirmed, as Leeuwenhoek did, that 
the swelling subsequent to the bite of Culex was due to the irritation produced 
by the tearing of the mouth-parts in the skin, without the aid of a poisonous 
secretion. After having experimented a large number of times with the living 
mosquito, I am convinced that there is use made of a poisonous saliva; for, when 
biting, if the mosquito fails to strike blood, which it often does on parts of the 
back of my hand, it may have inserted its proboscis (labium of course excepted) 
nearly full length, in from one to six directions, in the same place, and with- 
drawn its proboscis; indeed it may have inserted its proboscis, as often occurs, 
in extremely sensitive parts; yet in such cases, if no blood be drawn, no more 
effect is produced upon my skin than is produced by the prick of a sharp needle; 
a red point appears only to disappear in a few hours. Certainly there has been 
as much tearing of tissues in such a case as the above-mentioned, as there is 
when Culex settles on a place richer in blood, and, with a single probing, draws 
its fill. When the insect is allowed to draw its fill on the back of my hand, the 
subsequent swelling lasts from forty to forty-eight hours, and the amount of 
poisonous effect upon me, as proved by numerous experiments, is in direct pro- 
portion to the length of time which the Culex has occupied in actually drawing 
blood. The above-mentioned facts would indicate a constant outpouring of 
some sort of poisonous fluid during the blood-sucking process, and would neces- 
sitate a tube or channel for its conduction. Now, no other channel exists through 
which saliva could pass from the base to the tip in the mouth-parts which Culex 
inserts in the skin, and this, together with the position occupied by the salivary 
duct in other diptera, leads me to believe, without as yet being able to give 
anatomical proof for it, that the hypopharynx of Culex contains a duct that 
pours out its poisonous saliva. Having no fresh specimens of Culez ciliatus, and 
the extreme minuteness of the hypopharynx in the species of Culex available, has 
precluded my determination of the actual presence of glands in connection with 
this mouth-part. 
“The mandibles (figs. 1 and 8, m), the most delicate of the mouth-parts of 
Culex are two very thin linear-lanceolate lamelle of transparent chitin, which 
rest with their inner edges beneath each half of the hypopharynx, their outer 
edges projecting beyond its outer edge, on each side. At the base of the proboscis 
they appear to have no muscular attachments. They are slightly tapering from 
the base to the tip, but are of equal thickness throughout their breadth; at the 
tip they have a slight thickening, in form of a letter V, with its opening turned 
toward their very delicate, almost invisible tip. (See fig. 5, m.) 
“The maxille (mistaken by Gerstfeldt + for the mandibles, but correctly 
figured by Muhr { on his diagram as maxille) are tapering lamellx of chitin, 
apparently serrate at the tips. Hach maxilla is thicker near the inner edge, the 
thickening being formed by a solid chitinous shaft, which is fixed longitudinally 
upon the upper side. (See figs. 5 and 8, mz.) The bases of the maxille join 
im Re A. F. Mémoires pour servir & I’histoire des Insectes. ... . {Edition 17387- 
. 4, part 2. 
Gerstfeldt, G. Ueber die Mundtheile der saugenden Insecten .... 1858. 
Muhr, J. Die Mundtheile der Insekten dargestellt auf 5 Wandtafeln....1878. 
