156 Bulletin de la Société Royale Enlomologique d'Egypte 
I was able immediately to solve a very important 
practical! question. From rearings in the coast plain 
I received the flies from oranges at the beginning of 
November and in the middle of March. In the same 
time I observed oviposition in orange-groves. Was 
there another second generation between November 
and March ? It is clear that the danger for oranges was 
much greater if there are three instead of only two 
orange infesting generations. The average tempera¬ 
ture of this place is n,6° C. It is in the zone bellow 
the critical cold temperature, and an average deve¬ 
lopment in Hess than i 3 o days has to be excluded. The 
question of a third orange generation was so decided 
negatively. The unfavourable climatical conditions 
may produce a high mortality during this time. Fur¬ 
ther conclusions from the curves for the coast plain 
(type Sarona) give 7 generations, and agree well 
with my two years rearings. 
In the mountains (type Jerusalem) we estimate 
only 5 generations on account of the longer duration 
of unfavourable winter time. The larval mortality must 
be much higher than in the coast-plain on account of 
a five months’ average temperature of 7,5° C. The 
strong summer infestation in this country may result 
partially by rich importation of infested fruits. My 
breedings from three generations agree here also well 
with the estimated data. 
Although the Ghor (type Tiberias) is not yet 
infested, as far as my observations go, an estimation 
was desirable too for this country, to clear up the pos¬ 
sibility of damage. The 10 possible generations arise 
from an increase of one winter and two summer gene- 
