BIOLOGY OF PHILIPPINE CULICID/E. 



By Ghakles S. Banks. 

 {From the Entomological Section of the Biological Laboratory, Bureau of 



Science. ) 



Although nearly a hundred species of mosquitoes are now recorded 

 from the Philippine Islands and new ones are constantly being discovered 

 in every region where collecting is done, very little has been known here- 

 tofore of the habits and life histories of even the most abundant species, 

 among which may be mentioned Myzomyia ludlowii Theob., Stegomyia 

 persistans Banks, Culex fatigans Wied., and Culex microannulatus 

 Theob. 



While many species are perennial, others are abundant only at certain 

 times of the year. Of those breeding in or near dwellings some are 

 da}^ flyers while others are to be encountered only after dark, lieing most 

 prevalent before midnight. 



There are few people who, after a year or two of residence in this 

 region, are not able to recognize some of these pests either because of 

 their form and coloring, or from their habits. 



WoECESTERiA GKATA Banks. 



Worcesteria grata Banks, This Journal (1906) 1, 780, 982. 



Egg: The egg is 0.67 to 0.70 millimeter long and 0.43 to 0.47 millimeter in 

 diameter, of a very broad, blunt, regular ellipsoidal shape. _ (PL I, fig. 1.) It is 

 pure white when laid, but turus to a dirty pinlcish-gray previous to the hatcliing 

 of the larva. The surface appears granular when seen with a low-power lens (PI. 

 I, fig. 1 (a)), but when placed under a high power, small, sub-ovoidal tubercles 

 are seen. Some of these appear spherical with a spinous projection. These tu- 

 bercles vary greatly in size (PI. 1, fig. 1 (6) ), and their surfaces are coated with 

 a filamentous, powder-like substance, impervious to water. The egg is thereby 

 made to fioat perfectly upon the water, no part of it being submei-ged at any time. 

 The largest tubercles measure 0.014 millimeter by 0.01 millimeter (PI. I, fig. 1 

 ( c ) ) , while the smallest are about 1 fi. 



Wlien the larva is about to hatch, the egg shell splits irregularly 

 around the short circumference in such a way as to leave the ends joined 

 together by a narrow strip. (PI. I, fig. 1(d).) The eggs are laid 

 in the hollow stumps of bamboo in water which contains other mosquito 

 larvae. They are deposited during the late afternoon or early evening. 

 Mosquitoes in captivity lay about 20 or 35 eggs each day during a period 

 of two days. As many as 10 larvaa of the same size have been found in 



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