595 
REPORT OF THE CONSULTING ENTOMOLOGIST. 
Diamond-back Moth.— The observations on this pest are included 
in the detailed report (see page 596), of the recent attack. 
Mangel Fly Leaf Maggot. — In the earlier part of the summer — 
that is, during June and July — one of the most important infestations 
noticed has been that of the mangel fly leaf maggot, Anthomyia beta'. 
This was -widespread. I had notes of it from Knowle, and from 
the district near Rugby in Warwickshire, and from the Banbury 
district in Oxfordshire, as present in Herts and Cambrirlgeshire, as 
very bad near Hawkhurst, Kent, and as injurious in Devon, and 
especially hurtful over the North Devon district. 
The fii-st observations were sent me on June 22, and the amount 
of harm done was described by various correspondents in J une or 
early in July as " considerable damage " ; " scarcely a plant 
escaped " ; and " total failure." 
Notwithstanding this infestation being one which occurs more 
or less every year, the injury has in many cases not been recognised 
as attributable to insect attack, and inquiries have been sent me as 
to its being a newly-arrived trouble to mangel. It may make some 
difference in future attention to preventive measures for it to be 
more generally knovsTi that this patched and blistered state of 
mangel leaves is not due to damage from frost or sun-scald, but 
from the working of fly maggots in the tissues between the upper 
and under sides of the leaf. 
These small whitish or greenish maggots feed for about a month 
in the leaves, and then mostly drop from the leaves to the ground, 
where they turn to chrysalids, in small oval chestnut-brown 
chrysalis cases. From these the small grey-and-black two-winged 
flies come out in about ten days or a fortnight, and proceed to start 
new attacks by laying their white spindle-shaped eggs beneath the 
mangel leaves. Thus attack may go on all summer. 
The first burst of attack is usually much the worst, as the young 
plants with their small supply of leafage faU most rapidly under the 
injury. 
I have advised all inquirers that the best treatment appears to 
be the application of stimulating dressings, which may push on 
healthy leaf growth, and replace the leafage killed by the maggots 
as soon as possible. These may be chosen according to requirement 
of the land, but I have especially drawn attention to the successful 
use of nitrate of soda as a means of saving mangel much injured by 
maggot ; as shown, amongst other instances, at Eothamsted last 
summer. 
Cutting ofi" maggot-infested leaves, or pieces of them, and 
destroying them, answers excellently in preventing local and im- 
mediate recurrence of attack, but for the time being the removal of 
the leafage in this way is as injurious as the loss through maggot 
blisters. 
