THE MEXICAN ORANGE MAGGOT 325 



and most continuous, and it is, therefore, in this state that the work oi 

 combatting- it should be centered. (Fig. 121.) 



A very important phase of the .study of a pest of this nature is the 

 percentage of fruit which it destroys annually. The proportion, as sug- 

 gested above, is variable in different places and times of year. ] was told 

 Ijy the chief of the (3axaca Experiment Station that very frequently in the 

 late part of the season fully two-thirds of the orange crop is destroyed, but 

 this is not true for ever}' )'ear. Cuernavaca, in ]\Iorelos, produces man\' 

 mangoes and guavas but few oranges, comparatively. The proportion of 

 mangoes infected l)y the worm is tremendous. A large part of those in- 

 fected decay badlv enough to fall to the ground before they are gathered 

 for market. An equally large part are picked from the trees for market 

 before the decay has gone very far. In one of the mango groves visited in 

 late June, the fruit, as it was picked, was brought to a small clearing to 

 be sorted over. The fruit which had a soft spot in it was thrown into one 

 pile and what the sorters thought was good fruit was thrown into another. 

 The infected pile was fully one-half as large as the other, and that, too, when 

 one-fourth of the crop was dropping to the ground. Wishing to see if all the 

 mangoes in the good pile were without the worm, I purchased twenty and 

 helped the man select them. Before the twenty mangoes had been picked out, as 

 manv more had l)een discarded because of a tell-tale soft spot with a minute 

 hole through the skin in the center of it. T took the twenty mangoes that had 

 been selected so carefully and of the twenty, when cut into, found only 

 thirteen without worms. A rough estimate from the above figures shows that 

 fully three-fourths of the crop was infected. This is a fair type of the 

 majority of the groves of Cuernavaca: a few are worse and a few are better. 

 A visit to the Borda Gardens presents, perhaps, the extreme of infection. 

 .Almost utter neglect of the grove has made this a veritable insectary for 

 l)reeding the flies. On the other hand, a small and comparatively well culti 

 vated grove belonging to Sr. Gaudalupe Gutierrez shows a slightly less per- 

 centage of infection, without a doubt due to the better care of the place. 



The guavas are often infected to a worse degree than the mangoes. The 

 trees usually grow in among the mango trees so that the flies pass very readily 

 from one to the other. To find roughly the proportion of fruit infected with 

 the worm about three hundred guavas were opened ; out of this number 

 eighty were free from infection. In another grove one hundred and twenty- 

 five were opened and seventy-five had no worms in them, showing a much 

 lower percentage of injury. 



Yautepec. jMorelos, about sixty miles from Cuernavaca. jiroduces many 

 oranges and comparatively few mangoes. Unfortunately I was obliged to 

 complete the work of the expedition and leave for California before the end 

 of September, so that I was unable to see the attacks of the fly when the 

 orange crop was at its best, in Xovember. .-Mthough the season was early 

 yet considerable picking and shipping was being done. With the assistance 

 of an efficient guide visits were made to many orchards belonging to Sr. 



