96 



PAPERS EEAD. 



Life-History of Syritta oceanica Macq. [Dipt,] 



BY F. W. TERRY. 



This little syrphid was originally described from the collec- 

 tion of M. Bigot by Macqnart in 1854. The habitat given for 

 the type (a female) is rather vagne and suggests a wide distribu- 

 tion, being stated as ''De FOceanie, Otaiti et I^ouvelle Zelande.'^ 

 Although so common in the plains and lower elevations, hover- 

 ing around flowers, especially Compositae, its life-history had 

 remained obscure until a $ was observed ovipositing under the 

 partially detached bark of a small twig upon the ground in a 

 damp location, Pauoa, near Honolulu, on May 30th, 1909. Rot- 

 ten guavas were lying in abundance in the vicinity, but although 

 several female adults hovered around them, no further oviposi- 

 tion was observed. Upon examination, 33 eggs were found 

 loosely inserted. These hatched four days later (3, vi, 09), and 

 the larvae were placed in media similar to that surrounding the 

 place of oviposition, and consisting of wet, decayed Hepaticae 

 and guavas. These larvte fed up readily, remaining invariably 

 immersed in their pabulimi, with merely the respiratory tube 

 visible. They commenced to pupate June 22nd ; adults emerg- 

 ing July 2nd to 5th. The life-cycle is approximately thus : In- 

 cubation period, 4 days; larval period about 19 days; pupal 

 period about 11 days. Total about 34 days. 



Egg. — White, narrowly ovoid; .G x .2 mm.; the entire sur- 

 face uniformly covered with minute elongate thickenings of the 

 chorion, giving it that reticulated appearance so characteristic of 

 many Dipterous ova. 



Larva. — Upon emergence the minute larva is very transluc- 

 ent and difficult to distinguish from its moist food-material. The 

 adult larva is about 14 x 3 mm., pale testaceous and amphipneus- 

 tie, and bears a very general resemblance to that of Volucella 

 ohe.sa Fab. (a common non-indigenous species) but the stigmatic 

 tubes are relatively more slender and longer. The integument 

 is uniformly covered with short whitish hairs. 



Head. — Completely retracted and hidden, buccal cavity con- 

 spicuous, mouth-hooklets hidden. Antennae arise from a raised 



Proc. Haw. Ent. Soc. II, No. 3, May, 1910. 



