GALLS CAUSED BY FLIES 
75 
pea-like form on the aerial roots of various species of Cattleya , 
doing much damage; and Cecidomyia rhododendri causes 
bud-like growths on the twigs of various species of Rhodo¬ 
dendron. 
The Cabbage - root fly, Phorbia brassicae , is not only a 
Cabbage pest, but often does considerable mischief in turnip 
plots, causing swellings which resemble somewhat those of 
the Turnip gall weevil. Full particulars concerning its 
life-history, etc., are given in Theobald’s second report, 
“ Economic Zoology,” p. 68. It also attacks the Shep¬ 
herd’s Purse, Charlock, Jack-by-the-Hedge, Wall Mustard, 
and the Stock, but I am not aware that it causes galls to 
arise on these plants. 
Certain members of the genus Diplosis are well-known 
pests. D.flava and D. tritici attack wheat; the larvae of the 
former give rise to rosettes of leaves on the haulm ; those of 
the latter induce swelling of the glumes and flowers. Diplosis 
pyrivora, the Pear Midge, not infrequently causes serious 
losses in Pear orchards. It attacks the blossoms, and de¬ 
posits its eggs with the long egg-laying tube. The eggs 
hatch in from four to six days. About a fortnight later the 
fruit begins to swell abnormally, and is gradually hollowed 
out by the larvae, which, in common with other members of 
the genus, have the power of leaping. (See Board of Agri¬ 
culture leaflet, No. 53.) 
The “ Ribbon-footed corn-fly,” Chlorops iaeniopus Miegen, 
causes the malformation known as “ gout ” in the haulm of 
Wheat, Rye, and Barley, most frequently on Barley. “ The 
attack takes its common name of ‘ gout ’ from the swollen 
state of the heads when the ear is unable to burst the 
sheaths. Whilst the plant is still young, and the forming 
ear is wrapped in the sheathing leaves, the fly places her 
eggs either within these leaves or so that the maggot can 
make its way through them to the ear; there it usually 
eats away some parts of the lower portion of the ear, and 
then gnaws, or rather tears, a channel down one side of the 
stem to the uppermost knot, and beneath the leaves the 
