718 JOURNAL, BOMBAY NATURAL HIST SOCIETY, Vol. XXV III- 
In either event the moisture and warmth of the beast’s saliva seem 
to conduce to their development. It is specially to be noticed that the 
season of egg-laying coincides with the time when the cattle are shed- 
ding their coats and have the habit of licking themselves. 
The newly hatched larvae are worm-like, whitish and transparent ; 
they have minute spines over most of their body, which cause them 
to adhere to the walls of the oesophagus. In that situation they 
soon moult and assume the smooth stage. In the smooth condition 
they bore through the ccsophagal walls and wander slowly through 
the host’s tissues. This period of migration lasts some nine months, 
during which period growth is extremely slow. Towards the end of 
winter, at least in Europe, they make for a point in the region r f the 
animal's back and there penetrate the skin. A second moult then 
ensues, and the spiny character is once more assumed. Development 
is rapid and causes much inflammation. As it reaches maturity the 
larva grows still more spiny. It lives in the fully developed warble, 
feeding on the products of the inflammation which it causes and 
breathing through the hole in the skin. This period of life in the 
tumour lasts into the ensuing summer. The larva is then some 25 
millimetres long, bluntly oval in form, with a warty apj^earance. 
Its skin has become thick, and a powerful coat of subcutaneous muscles 
has been developed. The prickles are larger and more luimc-rous 
than in the previous stages. They are probably erected by the muscles 
and used to create irritation and a copious sccr'.tion of the pus on which 
the parasite feeds. During the period of rapid growth it is desirable 
that the parasite should have access to the external atmosphere and 
should enjoy a suHicient supply of oxygen. The larva therefore 
enlarges the hole through the hide and lies with the tail end, contain- 
ing the spiracles, in the passage, and the head end, hanging down- 
wards, in the cavity of the warble. 
AVhen the larva has become full-fed and reaches maturity, it works 
a way out through the aperture of the warble. In this the jDrickles 
on its skin assist, by preventing it from slipping backwards. This 
exit usually takes place at night, or at least between six in the evening 
and eight in the morning, a habit that was long ago known to Reaumur. 
By fixing little bags over the apertures of the warbles it has been 
ascertained that the larvse never emerge during the middle of the day. 
The larva pupates on the ground, taking shelter beneath a stone or 
clod of earth. The pupa, which is formed in the old larval skin, 
is dark brown and rather flattened on one side. In about twenty- 
five days the perfect insctfct emerges by forcing open the lid at the 
front end of the puparium. 
This account of the Indian CEstrids concludes the group of Cyc- 
clorhaphous flies. The next group brings us to the Diptera Pupi- 
para which are imaginal parasites. 
{To be continued.) 
