
TACHINIDAE OF AUSTRALIA 57 
Austra. sept’ and ‘N.G. [=new genus] ad Oestrophasia N. Holl.’, and Brauer & 
Bergenstamm’s determination label that reads ‘prosopina det. B. B.’ (specific name 
handwritten, remainder printed). 
Tribe ORMIINI 
This small tribe occurs mainly in the tropical and subtropical parts of the world, 
and contains some of the most aberrant forms to be found in the Tachinidae. 
Several genera have the chaetotaxy very reduced and have a robust form and curious 
head facies reminiscent of the Oestroidea. Biologically the group is particularly 
interesting because the first-stage larva is the most perfectly formed planidium 
occurring in the Diptera (though Glawrocara has a similar planidium: see under 
Glaurocarini) and the hosts appear always to be nocturnally active Orthoptera 
(crickets and Tettigoniidae s.l.). Many forms have the pallid coloration often 
associated with nocturnally active flies. 
At present the Ormiini are uniquely characterized by having the prosternal 
region of the thorax greatly inflated (usually more so in females than males) and 
visible when the fly is seen in profile. The function of this oddly modified prosternum 
is unknown; such a feature occurs in no other Tachinidae. Another very unusual 
character among Tachinidae that occurs in many Ormiini is the reduction of the 
ocelli, some genera having the ocelli vestigial or totally wanting; all the ormiines 
so far known in the Australasian fauna and in the African fauna are without ocelli. 
In the Oriental fauna the genera Homotrixa Villeneuve and Xanthooestrus Villeneuve 
possess ocelli, but in these genera the prosternal membrane is only moderately 
inflated (Homotrixa) or not noticeably inflated at all (Xanthooestrus) and it is not 
certain that the genera truly belong in the Ormiini. 
The existence of forms such as Xanthooestrus, which has an entirely ormiine 
facies but has a normal prosternum, and of forms such as Glaurocara, which has 
a different morphological appearance yet has a perfect planidium larva and host 
relations like the Ormiini, poses the question of whether the Ormiini ought to be 
redefined on a much wider basis than at present. It appears now that a definition 
of the Ormiini to include only those forms with inflated prosternal membrane is 
too restrictive, and that several forms placed outside the group at present should 
be brought into it. At present, however, insufficient is known of these generally 
rather rare forms to permit any worthwhile re-evaluation of the Ormiini on a world 
basis, and the Ormiini is here accepted in its usual confined sense with the 
Glaurocarini recognized as a separate (rather intangibly defined) tribe. 
The main characteristics of the Ormiini are as follows. Eyes very large, bare, facets 
conspicuously enlarged in most males; head of ¢ usually holoptic or almost so, ¢ frons 
therefore virtually absent; ocelli present or absent, when present often strongly raised in g; 
inner vertical setae absent in male, usually present and converging or crossed in 9; proclinate 
orbital setae absent in g, weak in 9; parafacials bare; epistome not projecting, invisible in 
profile, often formed into a receding strip which curves for a long distance between a reduced 
face and the oral cavity; oral cavity, proboscis and palpi often exceptionally reduced; vibrissae 
present or absent, when absent lower ends of facialia usually formed into broad haired areas 
on each side of the epistomal strip; genal dilation weak or virtually absent; occipital region 
