(7 saute -) 
verticalis [Cantharid@] expected ; but you will no doubt be able to determine 
what it is when you seeaspecimen. The fly is about the size of a small 
wasp; the body covered with short grey hair; the abdomen striped black 
and grey; the wings membranous and transparent, with a dark marking 
across the centre; the head is furnished with a proboscis and a dart as fine 
as the sting of a bee or wasp. I found the fly, now identified, sucking the 
nectar of flowers, especially of the pink scabious and thistle, plants common 
in the Troad. (Later on I counted as many as sixteen flies on a thistle- 
head.) The number of flies rapidly increased daily until the 13th, when 
the ground appeared pitted all over with small holes from whence the 
parasite had issued. A few pup were then still to be found—a larva 
the rare exception. The pupal state thus appears to be of short duration. 
It was very interesting to watch the flies appearing above ground: first the 
head was pushed out; then with repeated efforts the body followed; the 
whole operation was over in two or three minutes: the wings were expanded, 
but the colours did not brighten until some time after. Occasionally a 
pupa could not cast off its envelope and came wriggling out of the ground, 
when it was immediately captured by ants. Unfortunate flies that could 
not detach the covering membrane, adhering to the abdomen, also fell a 
prey, as indeed many of the flies that could not get on their legs in time. 
The fly for the first time (13th June) was seen to pair, but this rarely. 
There is no disposition at present, so far as has been observed, on the part 
of the fly to approach the locust. It will be a point of the greatest interest 
to ascertain when and how the egg of the parasite is deposited—whether in 
the body of the locust before the insect buries its own eggs, or in the egg- 
pod in the ground. I have heard so much circumstantial evidence of the 
existence of a larva in the body of the locust that I no longer entertain any 
doubt on the subject; but whether it be the same as found in the pod is 
another question. [Certainly not.] The prolific increase of this fly shows 
it to be a natural enemy of the locust, a circumstance of which advantage 
should be taken. May not the strange non-hatching of expected locusts in 
infected districts, observed occasionally, be due to the destruction of the 
egg by the parasite ? 
“Tsend by post specimens of the ‘ parasite’ locust-fly. Of the pupe 
none are procurable, for they die when brought in-doors, thus showing that 
the insects require heat at this stage; and, if there be an intention of 
removing them from one country to another, this must be done when 
in the larval state. I inclose a skin thrown off by the pupa, which will 
give an idea of the shape. I shall write you further on the subject 
of this fly.” 
According to the observations of Dr. T. Algernon Chapman, of 
Hereford, ‘‘On the Economy, &c., of Bombylius,” the process of oviposition 
is effected while hovering in proximity to the locality frequented by its 
D 
