70 [ DISEASES OF CITRUS TREES 



before its time, and if the tree is suffering from want of 

 irrigation or from protracted drought, a certain proportion 

 of the punctured fruit soon drops down, even before 

 the young larvae are hatched. In hot weather with 

 southern winds and dewy mornings, the. eggs are hatched 

 in about a week, and the young grubs soon reach the 

 pulp, and in a few days more the fruit drops and rots. 

 If cold weather sets in, the eggs are not hatched, and 

 linger under the peel to hatch in the first hot days of 

 spring, although considerable numbers of eggs are 

 generally killed by the cold weather. 



The larvae, which are very similar to cheese maggots, 

 when arrived to maturity, pierce the peel and if the 

 fruit is still hanging on the tree, they let themselves 

 drop to the ground, and bury themselves in the soil to 

 the depth of i to 6 c. m., and in about six hours become 

 transformed into a pupa or chrysalis, having the form 

 and colour of a grain of wheat, but much smaller. If 

 hot weather continues, the pupa in five to eight days 

 develops into a perfect insect, which issuing from the 

 ground, proceeds with great alacrity to copulate and 

 to renew the havoc. But if cold and damp weather 

 supervenes many of the pupae die, and only a small 

 percentage manage to keep alive till next spring, when 

 the perfect insect issues forth to destroy the remaining 

 fruit in the orange grove. The eggs of the fruit- fly 

 which have hybernated are hatched by the warmth of 

 the first days of spring. So that in spring there are 

 really two broods, one from the newly laid eggs represents 

 the first brood of that year, the other represents a 

 part of the last brood of the preceding year, the eggs 

 having been dormant during winter, more or less 

 effectually protected from the cold by the thick peel of 

 the fruit. The larvae of the first brood mature about 

 the close of spring, and after going through the stages 

 already described, the fly leaves its underground abode 

 and proceeds to lay a second brood. The sufferers 



