On the Biology and Economic Significance of 

 the Chalcid Parasites of Australian Sheep 

 Maggot-flies. 



By Professor T. Habvey Johnston, M.A.. D.Sc, and 

 O. W. TiEGS, M.Sc, Walter and Eliza Hall Fellow in 

 Economic Biology, University, Brisbane. 

 (Plates IX. and X.) 



{Bead before the Royal Society of Queensland, 25th July, 1921.) 



Sheep maggot-flies are amongst the commonest and most 

 widely spread insects in Australia. When one tal-ces into 

 consideration the extensive degree of parasitism exhibited by 

 Hymenoptera upon other insects, it might reasonably be 

 expected that numerous species would }*e found which depend 

 for their existence on this abundant food supply. A number 

 of such wasps have actually been discovered in Australia, 

 mainly by ]\Ir. W. W. Froggatt, of Sj^clney. In the jDresent 

 ]iaper three other primary parasites f)f sheep blowflies are 

 recorded. Careful search would, no doubt, reveal the presence 

 of other species. 



The forms hitherto recorded are — (1) Nasoma brevicorniit 

 Ashmead ; (2) Dirhinus sarcophagce Froggatt ; (8) Chalcis 

 rallijihorce Froggatt ; (4) HemUevomyia abrupta Dodd. The 

 following forms in addition to Xos. 1. 2, and 3 have been 

 found parasitizing either the larvse or the pupae of blowflies 

 in Brisbane under natural conditions : — (5) SpaJangia musci- 

 darufn Richardson ; (6) an Encyrtid wasp, for which the name 

 Aiislralencyrtus giraulti, n. gen., n. sn.. is proposed ; ('/) and 

 a Proctotrypid (Diapriid) wasp, apjiarently also new, for 

 which we propose the name ParaspUoinicnis froggatti, n. gen., 

 n. sp. (8) An eighth species, Pachycrepoideus dubius Ashmead. 

 has been recorded by Girault,from North Queensland, where no 

 doubt it parasitizes Muscoid flies, as elsewhere. (9) Probably 

 Chalcis diplerojihaga Girault & Dodd is a parasite of blowflies. 



In the present paper we give (.A) an account of the biology 

 of some of these forms, together \\ith some general remarks 

 on each species : (B) a discussion of the role they can be made 

 to play in the control of the sheep flies ; (C) a description of 

 two apparently ncAV wasp parasites of Australian blowflies. 



Some information relating to these hymenopterous para- 

 sites of flies has been recently published })y one of us (Johnston, 

 1921). 



