TO 
A Monograph of Culicidae. 
During the past year I have had two generations of Cnlex 
nigritulus in an outdoor barrel which can have had no blood, 
except that of some Chircnomidae that hatched out in the same 
receptacle. 
Yet we find that some species apparently must have their meal 
of blood to deposit fertile eggs. In the previously-quoted Report 
by Major Ross on page 21 we find it stated that, “it seems 
that a meal of blood is necessary before fertilization.” Naturally- 
fed gnats were found to invariably lay eggs after two or three 
days; those which were bred from larvae in captivity, and had 
been isolated and fed in test-tubes, never did so, although before 
being isolated they had long been in company with males. The 
inference is that fertilization takes place only after the female 
has been fed.” 
Lastly, it was observed, that “previously-fed and fertilized 
insects would lay a second batch of eggs after a second meal of 
blood without a second fertilization, but never laid a second 
batch of eggs without a second meal of blood. That is, one 
fertilization suffices for several batches of eggs, but one meal of 
blood for one batch of eggs only.” 
These observations agree with those made in India by 
Major Ross, and thus the following law may hold good for 
some of the Culicidae that feed on man, at least for a few 
of the commoner species—“ the insects require blood for the 
propagation of their species .” 
It does not follow because one insect lives in a certain way, 
that closely-related species need do the same, and the fact that 
both C. nigritulus and C. pipiens will oviposit fertile eggs without 
any meal of blood in Europe need not detract from the previously- 
quoted phenomenon. Some of those species which live with man 
may have acquired the habit of blood-sucking, which has become 
an essential feature of their life in regard to the maturity of the 
sexual organs in the female. 
But after observations made during the last ten or twelve 
years on European Culicidae I feel bound to state that blood is 
not an essential for the majority of European species, and in this 
Professor Howard agrees in connection with the Culicidae of 
America. “Female mosquitoes are normally, without much 
doubt, plant feeders,” says Professor Howard, “and the state¬ 
ment that not one in a million ever gets the opportunity to 
taste the blood of a warm-blooded animal is unquestionably an 
under-estimate.” 
