1961] 
Insect Control Programs 
95 
cents a box. Some loopholes were exposed. For instance, mangoes, 
which do not stand up well to fumigation, were sent unfumigated to 
Chicago, but were found to have been transshipped to Louisiana, a 
state vulnerable to the fly because of its mild winters. 
Although over four and one-half million automobiles were examined 
at roadblocks, the spread of the fly mainly followed the highways, 
indicating that contraband fruit or adult female flies were moving by 
car. Other minor routes of dispersal occurred through Indian reser- 
vations, where mangoes were peddled after being transported by 
canoe and otherwise away from the roads, and through the traffic 
of guava pickers, who are independent and have their own pickup 
stations. 
Direct control methods employed a spray containing a bait of 
protein hydrolysate (“sauce base” of the food industry) plus a poison 
component, the organic phosphorus compound, wettable malathion, 
mixed in just enough water to make up a spray that could be applied 
by air. This bait attracted flies from distances of over 200 
yards away, instead of the few inches or feet over which the 1929 
sweetened bait had proved effective. The new bait lured and killed 
almost all flies within 100 feet a few hours after their emergence, so 
that swaths missed by the planes did not matter so long as they were 
not excessively wide. By proper timing of sprays at seven to ten days 
apart, the flies were prevented from ripening to sexual maturity after 
eclosing from the pupal stage. Since the maggots were able to survive 
(in grapefruit and oranges left on the tree) for up to 20 days after 
reaching the final larval stage, the spray was continued for one full 
generation (50-90 days) after the last fly find. 
Detection methods depended primarily upon substances that would 
lure male flies. Angelica seed oil in plastic traps with poison proved 
to be a highly effective attractant for males, but the different lots of 
the oil that were tried were found to be very uneven in their effective- 
ness. Furthermore, this commodity was rare and expensive — $100 
or more per pound. By early 1957, some 800 pounds of the oil (the 
entire world production of ten years) had been used for fly baiting, 
virtually exhausting the world supply. The last angelica seed oil 
was offered on the world market at $500 a pound. Fortunately, at 
just about this time the chemists came through with an effective and 
relatively inexpensive substitute that they called siglure, containing 
certain simple esters of cyclohexane carboxylic acid. It was learned 
that the fruit flies tend to disperse from areas after fruit production 
has ceased, and this was a good reason for leaving fruit on the trees 
in infested areas. Fallen fruit was destroyed wherever possible. 
