jan. io, 19x6 Effect of Cold Storage on Mediterranean Fruit Fly 663 
and sixteenth days of refrigeration, although 4,475 were under observa¬ 
tion. Only 5 eggs hatched out of 401 removed on the eighth day, and 
23 out of 152 removed on the sixth day. 
Temperatures ranging from 33 0 to 34 0 proved fatal after the eighth 
day; 45 eggs out of 300 removed on the eighth day hatched. No eggs 
hatched out of 6,051 removed between the ninth and eighteenth days 
of refrigeration. 
At 34 0 to 36° eggs were examined only on the eleventh and thirteenth 
days of refrigeration. No eggs hatched out of 236 and 241 removed 
after these periods of refrigeration. 
All the eggs subjected to a temperature of 36° were not killed until 
after the eleventh day of refrigeration. Out of 652 eggs removed from 
storage on the eleventh day, .2 hatched; and out of 301 eggs removed 
after 10 days, 27 hatched. No eggs hatched out of 3,305 removed after 
from 12 to 17 days of refrigeration. No appreciable mortality occurred 
at this temperature until after one week. 
No eggs held at 36° to 40° were examined until the ninth day of 
refrigeration. Out of 1,012 eggs removed in small batches daily between 
the ninth and nineteenth days of refrigeration, none hatched. 
Only 602 eggs were used for refrigeration at 40° to 45 0 . No eggs 
hatched after a refrigeration of 21 days. Two eggs out of 67 refrigerated 
for 20 days hatched on removal to the laboratory. No eggs hatched of 
those removed after 21 to 25 days of refrigeration. 
THE larva 
Larvae in the third instar proved more resistant to cold than larvae 
in the first and second; and all instars are generally more resistant to 
low temperatures than are the eggs. (See Table I.) 
A temperature of 32 0 F. was found fatal to larvae of the first instar 
after the eighth day of refrigeration; 2,558 larvae removed after refrig¬ 
eration from 9 to 14 days were found to be dead. The data in Table I 
show that 2 out of 845 were alive on the eighth day of refrigeration 
and only 11 out of 454 on the seventh day. This temperature did not 
appear to affect the first-stage larvae appreciably until after the fifth 
day of refrigeration. Larvae of the second instar failed to live after the 
ninth day, and very few lived that long; but 11 out of 473 and 20 out of 
423, respectively, were alive after the eighth and ninth days of refrig¬ 
eration. All of 1,868 second-instar larvae were found dead on removal 
from storage after the tenth to fifteenth days of refrigeration. Only 6 
out of 332 larvae of the third instar were alive on the eleventh day of 
refrigeration; 626 larvae removed after 12 to 15 days of refrigeration 
were found dead. 
• A temperature of 32 0 to 33 0 had practically the same effect upon 
5,352 larvae as did 32 0 . 
