3i8 



Journal of Agricultural Research 



Vol. Ill, No. 4 



TabliJ \'. — Effecl of oil fi urn rind of orange and lemon upon the haUhing of eggs of the 



Mediterra nean fruit fly 



Period of (Icpositing egg.s. 



1.30 p. m., Mar. 23. to 9 a. m.. Mar. 23 



9 a, m. to I p. m.. Mar. 37 



9a. m., Mar. 27,10 9 a.m.. Mar. 28. ■ . 



Total 



Treated 

 with oil. 



800 

 400 

 400 



800 

 400 

 400 



Number of esKs 

 hatched. 



Treated. Check, 



3 

 119 



609 

 342 



364 



Further evidence that the oil in the ruptured cells is the killing agent 

 is the very small mortality among the eggs deposited in the Chinese 

 oranges. Since in this fruit the rind is only about two twenty-fifths of 

 an inch in thickness, the female is compelled to deposit her eggs either 

 through the rind into the pulp or in a position between and parallel to 

 the rind and pulp, but at a distance from the puncture that seems to be 

 a protection from any oil set free by the puncturing process. Of 609 

 eggs thus deposited between the rind and the pulp 600, or 98.5 per cent, 

 hatched, as determined by an examination of 85 fruits one week after 

 they had been picked. A comparison of the 98.5 per cent hatched in 

 Chinese oranges with the percentage of the mortality among eggs in 

 other citrous fruits emphasizes the part the oil has in causing mortality 

 among eggs. It is also interesting to note in passing that the eggs in 

 Kusaie limes, the rind of which is sufficiently thick so that the eggs are 

 deposited directly beneath tlie puncture, die with great regularity, while 

 the eggs in Hawaiian limes, the rind of which may be sufficiently thin to 

 permit the eggs being deposited as in Chinese oranges or so thick (accord- 

 ing to the indi'vidual tree) that the eggs are laid either in the cavity in 

 the rind or between the rind and pulp but directly beneath the puncture, 

 suffer a degree of mortality between that of eggs deposited in Chinese 

 oranges and Kusaie limes. 



While in Chinese oranges the eggs deposited between and parallel to 

 the rind and pulp hatch with great regularity, those deposited through 

 the rind into the pulp are subjected to a mortality caused either by exces- 

 sive moisture or lack of air. Eggs thus laid are usually placed beneath 

 the skin covering the pulp, and the fascicle which they compose 

 appears, after the rind has been removed, as a dull white spot that is 

 easily overlooked. Usually no trace of the opening through the skin 

 covering the pulp through which the eggs have been deposited can be 

 found. The eggs appear thoroughly sealed within the pulp. In some 

 few instances the opening is distinct and occasionally an egg is left in it, 

 half in and half out of the pulp. When these openings in the skhi occur, 

 the eggs appear to hatch normally. Egg masses deposited entirely 

 within the pulp may be located externally a few days after oviposition 



