3872 JOURNAL, BOMBAY NATURAL HIST, SOCIETY, Vol. XXVIII. 
an acuter sense of hearing is necessary to those forms in their search 
for hosts. The Cyrtid@ for instance are a group which have developed 
extremely large tegule which conceal the halteres and are probably 
accessory to a highly developed auditory sense. In Diptera auditory 
organs are placed at the base of the wings and may well be sensitive to 
air-waves which make no impression on our ears. The halteres 
in Diptera are supplied by nerves only second to the optic nerves which 
are the largest in the insect’s body. The tegule of Diptera are very 
possibly functional in collecting sound waves and increasing the per- 
ceptive power of the organs in the halteres. It seems safe to assume 
that in those dipterous groups which have no tegule, the halteres 
chiefly perform a function of equilibration ; but in those groups which 
have highly developed tegule such as Cyrtide, Tachinide and most 
Cistride, the halteres are mainly organs of hearing. So the presence 
of large well-developed tegule in the parasitic flies indicates the 
presence of a highly developed auditory sense in the halteres. 
The tegule, if this view is correct, are analogous with the carti- 
laginous external ears of mammals. 
Between 40,000 and 50,000 species of Diptera have been described 
and these have been distributed by modern systematists into about 
60 families. The life histories of the parasites are among the most 
amazing things in Nature. Diptera are not popular insects even 
among entomologists. Beelzebub in Hebrew is the Prince of Flies 
but protects his votaries from the molestations of these pests. If 
this paper should induce one person in India to become a collector 
of Diptera or, better still, an investigator of their life histories, about 
many of which nothing is known, it will not have been written 
in vain. 
It will be convenient to show in the form of a table the families 
of Diptera in which parasitic habits have been developed. 
DIPTERA. 
I. Orthorrhapha. 
Nematocera .. None are parasitic. 
Brachycera .. .. Bombylude Cyrti- 
de=Acroceride ‘Larval parasitism. 
II. Cyclorrhapha. 
Aschiza ne .. Phoride & 2) 
bg oe .. Pipunculide : 
Schizophora .. .. Conopide BS 
se . Tachinide .. .. | Larval parasitism 
.. Dexriide 
. Muscide 
.. >» in many members 
. Sarcophagide staid 
of these groups. 
. Kstride 
