178 
Ohservations on the various Insects 
claws and 2 small cushions oi' pulvilli : it is 3 lines long, and the 
wings expand 5 lines. 
I am disposed to think that I have bred a closely-allied species 
from similar larva? in the carrot roots, but the flies were so muti- 
lated before I discovered them, that I cannot be certain ; it seems, 
however, more than probable, because Psila Rosoe I have never 
found in my garden, whilst the species I allude to (P. niyiicornis^ 
is abundant there. 
3. Psila nigricornis of Meigen* is very like jP. Rosa, but rather 
smaller, and the 3rd oval joint of the horns is entirely black. I 
think it far fi-om improbable that it may be only a variety of that 
insect. 
It is not always the mature crops which suffer from these mag- 
gots, for some young carrot roots, sent to me the first week in 
July, 1845, from Castel Connel, in Ireland, were drilled through 
by them, as shown at fig. 12; and previously, in 1842, young 
crops were similarly afTected, but the maggots were not discovered 
where the spots existed, owing probably at that time to the 
minuteness of the recently produced larvae. 
With a view of rescuing the carrot crops from this pest, it has 
been recommended that as soon as the outer leaves become yel- 
low and wither, which are indications that the root has been 
infested, such plants should be taken up without delay, and the 
grubs destroyed by immersing the roots m hot water. 
If land be left, as allotments often are, to remain through the 
winter just as the crops have been drawn, not only that plot of 
ground, but the whole neighbourhood, may be deluged with noxious 
and troublesome insects : whereas, by trenching in the autumn, 
the pupse of these and other flies are not only subjected to frost, 
snow, and rain, as well as extreme transitions of temperature, but 
the inhabitants of the soil are exposed to the prying eye of the 
rol)in and various birds, which subsist to a great extent upon 
insects and seeds during the winter. 
Before sowing carrots, it is a great security against the Rust 
to give a dressing of spirits of tar and sand. It is even reported 
that pigeons' dung or cow-dung, pointed in at the time of sowing, 
will secure the crop from these maggots. Old turf well incor- 
porated with quick-lime, at the rate of 80 loads per acre, on a 
light soil, produced a fine crop entirely free from insects. f If 
quick-lime alone be sown over the surface, let it lie two or three 
days and repeat the operation, after which it is to be ploughed in : 
this will free the soil from insects and slugs which prey upon the 
* ' Systematische Be.schr. Euiop. zweif. Insecktur,' vol. v= p. 359. 
•i' ' Caledonian Hort. Soc.,' vol. vi. p. 2. 
