S BULLETIX 1081, U, S. DEPAET:MEXT OF AGPJCULTTJEE. ^ 



drop at the puncture. (PL II, at right.) It is possible thereby to de- 

 termine easily the number and location of the f)unctures. 



SEASONAL HISTORY AXD OCCURRENCE. 



The insects breed throughout the year in Florida and are present 

 in all stages at any month of the year. They have, however, some 

 seasonal preferences and occur in much larger niunbers at some 

 seasons than others. The time of greatest flight of the adults seems 

 to be during March and Aj^ril, while in late summer and fall there 

 are very few of them in evidence. This is correlated largely with 

 the growth of the host plants, which begin fruiting usually in the 

 fall and continue through the winter and sjjring. Many of the 

 plants die down or are cut out in the late spring and new ones set. 

 The flies therefore appear on the new fruits in the fall and con- 

 tinue to breed in increasing numbers throughout the winter and 

 spring. The wild papayas in the hammocks fruit at all seasons and 

 always serve as hosts whether or not any of the cultivated sorts 

 are available. The generations are by no means marked and vary 

 in length from 40 days in summer to 70 or more in colder weather. 

 In a year's time there are about six generations, although they over- 

 lap and are in no way distinct. Moisture in the soil is a very im- 

 l^ortant regulating factor in the length of all stages, perhaps even 

 more so than changes of temperature. 



POWER OF FLIGHT. 



The distance which the adults are able to travel is not very great, 

 for they are not strong fliers. One planting of papayas under obser- 

 vation was placed 2 miles from where any other plants existed and 

 remained fi^ee from infestation throughout the season, the adults 

 apparently being unable to cover that distance. In most locations, 

 however, there are wild papayas all through the surrounding ham- 

 mocks, and these serve to harbor and spread them. 



SUSCEPTIBILITY OF VARIETIES. 



While no distinct varieties of the papaya {Carica papacy c.) are 

 recognized, there are several types of the fruit grown in the State. 

 Several have been introduced from foreign countries and crossed on 

 existing types. Then there are the original wild plants which have 

 been cross-pollinated on the cultivated plants through natural 

 agencies. Through all this cross-pollination there result two rather 

 distinct types of fruits, one the small, round, or oval type with 

 rather thin skin and flesh and the other the large, oblong fruits which 

 usually have thick flesh. One especially fine fruit of the latter type 

 has been produced at the Plant Introduction Gardens at Miamij.Fla., 



