310 



THE MONTHLY BULLETIN. 



the adult requires about three months, thus permitting of four broods yearly. The 

 female fly lays about seventy eggs, depositing them in quantities usually not to 

 exceed eight or ten in a single fruit. From this it would appear that the spread of 

 this fly, once introduced, might be accomplished with alarming rapidity. 



It is exceedingly difficult to obtain accurate figures showing the damage caused by 

 the Mexican orange maggot. The list of hosts include oranges, grapefruit, sweet 

 limes, mangoes, peaches, plums, Acliras sapotes and guavas. Mr. Isaac informs us 

 that the production of oranges in certain localities of Mexico had been abandoned 

 because of the activities of the fruit fly. He further states that the production of 

 mangoes in such districts had been reduced to one-fifth of the normal crop. 



In the horticultural records of California many instances are found of the capture 

 of this insect in fruits offered for entry from Mexico. One such instance showing 

 the danger of its introduction and the justification for the endless vigilance of the 

 quarantine officers occurred at San Diego May 13, 1915. At that time thirty-two 

 living pupae of the Mexican orange maggot were found in a small package of guavas 

 en route by parcel post from Mexico to Pasadena. This consignment coming at the 



Fig. 110. — The Mexican orange fly (Trypeta 

 ludens) ; (1) male, dorsal view; (2) female, dor- 

 sal view; (3) pupa; (4) larva; (5) female ovi- 

 positing on orange; (6) female ovipositing on 

 suava; (7) female ovipositing on mango. The 

 first four figures are greatly enlarged. The last 

 three are greatly reduced. 



very height of the orange season to Pasadena, situated as it is within the citrus belt, 

 would afford a splendid opportunity for the spread of the fruit fly. 



The attempts at control of the fruit fly in Mexico have demonstrated that this is 

 a very serious problem. The best results seem to be obtained by two separate and 

 distinct processes aimed the one at the adult and the other at the maggot. A sweet 

 poison spray is used to control the adults with varying degrees of success. The most 

 effective control against the maggot is to collect and bury or burn all fallen fruit. 

 This work to be effective must be done frequently, and in season would be an almost 

 endless task. In view of the labor situation which exists in our farming communities, 

 such a procedure would mean a very serious hardship upon the fruit grower, and the 

 prime purpose of quarantine regulations and the activities of quarantine officers is 

 to prevent any possibility of this additional cost to crop production by keeping this 

 pest out of the state. 



