108 
WARBLE FLY. 
maggots leave the cattle between evening and morning, and likewise 
regarding the effect of cold in lengthening the time before the fly 
leaves its chrysalis-case ; also his method of rearing the fly for exami¬ 
nation is of interest practically, as in this way all so disposed may 
secure specimens, and be able to recognise this insect-pest when on the 
wing amongst the herd. 
In regard to the time at which the full-grown maggot squeezes 
itself out of the warble, Mr. Martyn found this always took place in 
the morning, or at some time between six o'clock in the evening 
to about eight o’clock the next day. To secure the warble-maggots, 
when fully-developed, he fixed a little muslin bag over one or two 
warbles, and in this way prevented the maggots dropping to the 
ground; but, as there were difficulties in managing this method, he 
tried putting a ring of bird-lime round the hole, and found the maggots 
fixed in this in the morning, but never in the middle of the day. 
The chrysalis-stage he found lasted about twenty-five days, as 
noted with eighteen specimens, but to see how far heat or cold caused 
a difference in the duration of this state, Mr. Martyn put four 
chrysalids by themselves, and kept the temperature they were in much 
lower. These developed to flies in an average of thirty-six days,— 
that is, over ten days later than the others. The flies were not so fine 
or well-marked, nor were they quite so large as the others. 
The fly is figured at commencement of this paper : in the case 
of five of the twenty-five reared by Mr. Martyn, the portion of the 
abdomen beyond the transverse black band was grey instead of yellow 
or orange. This point is worth observation, as there may be some 
variety of the fly at present undescribed. 
We now, I believe, only need observations of the exact position 
where the egg is laid to complete the life-history of the Warble Fly. 
Any observations, and especially all information practically bearing on 
checking fly-attack in summer, will be very acceptable for future 
publication, and, with another season’s observations added to those 
already contributed, it may fairly be hoped that we may then have 
sufficient well-proved information to afford material for a special 
publication, fully illustrated, of the complete history of the Warble 
Fly, and method of treatment successful in checking its increase and 
ravages. Meanwhile, it would give me much pleasure to forward any 
information in my power, or, if wished, a copy of these “ Observations ” 
to any who will communicate with me. 
