380                       Bionomics of the Ox Warble-Fly

The presence of warble tumours in dairy cows and of oesophageal larvae
in bulls born and bred at Mukteswar shows that the pest is indigenous to this
locality.

During 1937, the occurrence of oesophageal forms of H. lineatum was
noticed for the first time at Mukteswar towards the end of March and thence-
forward they were encountered continuously during an observation period of
nearly seven months. The significance of their occurrence over such a long
period is not understood and it would appear difficult to reconcile this with the
generally accepted view that there is only one annual brood of H. lineatum
in India.

Evidence has been obtained that the presence of warble tumours results in
a loss of condition of the affected animal.

                                     ACKNOWLEDGMENTS

The writer wishes to express his thanks to the Imperial Council of
Agricultural Research and to the Director, Imperial Veterinary Research
Institute, Mukteswar, for providing funds and facilities to undertake this
work. His thanks are also due to Mr. S. K. Sen, Entomologist of the
Institute, for his useful suggestions and guidance. The illustrations were
prepared by Mr. Ahmed Baksh and Mr. S. Sen Roy, artists of the Institute,
and for this the writer is indebted to them.

                                          REFERENCES

Bishopp, F. C. and others (1926). U. S. A. Agric. Bull. 1369, pp. 1-119.
Cross, H. E. (1926). Agric. Res. Inst. Pusa Bull. 160, pp. 1-16.
Fletcher, T. Bainbrigge and Sen, S. K. (1930-31). J. of C. Bur. for Anim.
Husb. & Dairying in India, 4, 127-138.
Knipling, E. F. (1935). J. Parasit. 21, 70-82.
Laake,E. W. (1921). J. Agr. Res. 21, 439-457.
MacDougall, R. S. (1935). Vet. J. 91, 472-481.