Nov. 25. 1918 Biology of Fruit-Fly Parasites in Hawaii 



459 



Before discussing the relation of G. sihestrii to the other fruit-fly para- 

 sites, a brief summary of its hfe history will be given. 



Under ordinary circumstances the Galesus female attaches herself to 

 the fruit-fly puparium (Pi. 32, E), inserts her 

 ovipositor, and within 3 to 15 minutes places 

 an &gg into the fly pupa. The subelliptical 

 egg (fig- 36) hatches in 2 to 3 days. The 

 newly hatched larva (fig. 37) is strictly an in- 

 ternal feeder. Its general structure is strik- 

 ingly like that of the newly hatched opiine 

 larva. The heavily chitinized head, bearing 

 long, curved mandibles, and the soft segmented 

 body strongly suggest a close relationship to the 

 opiines as shown in figures 3, 4, 23, 24, and 28. 

 No tracheae occur in the first-instar larva. 

 With the molt to the second instar (fig. 38), the 

 chitinized head is lost and the body is simple, 

 without strong characters, and very much re- 

 sembles the second-instar lar\^8e of the opiines. 

 A third instar occurs, resembling the second. 

 Whether or not there is an intermediate stage 

 between the third and the last has not been 

 determined. With the molt to the last larval 

 instar a strong, well-defined^ open tracheal sys- 

 tem appears, with three pairs of large stig- 

 mata. The stigmata are borne on the first 

 three segments back of the head. Heavily 

 chitinized, sharply pointed mandibles are pres- 

 ent (fig. 39). No waste material is voided by 

 the larva. The midintestine is filled with this 

 waste and is closed caudally. Just before pu- 

 pation, in the prepupal stage, the entire waste 



accumulation is discharged. 



Into this meconium the ex- 



uvium of the mature lar\^a is 



shed upon pupation. The 



pupa then lies with the caudal 



tip embedded in the voided 



meconial mass and the 



crumpled lar\^al exuvium. The entire egg, larval, and 



pupal period averages, in Honolulu, from 25 to 32 

 days, depending upon the temperature. The adult emerges usually by 

 pushing off the dorsocephalic cap of the puparium (fig. 40). Mating 

 and oviposition occur immediately upon emergence. The female flies 



Fig. 39. — Galesus sihes- 

 trii; Mandible of ma- 

 ture larva. Length 

 0.085 mm. 



Fig. 38. — Galesus sihestrii: Larvaof 

 second instar. Length 1.5 mm. 



