Mangold or beet fly. 
55 
Prof. W. M'Cracken, writing from tlie Royal Agricultural College, 
Cirencester, mentioned :—“ The Mangold Maggot was very prevalent 
in the first half of June, but the damage done, owing to the rapidity 
of growth at that time, was hardly appreciable.” This point of rapid 
growth is, as far as ice see at 'present, about the only way by which the 
effects of this kind of Maggot-attack can be reliably counteracted. 
Pinching out the infested parts of the leaves, and crushing the Maggot 
in the blistered or dead patch which it has formed by gnawing away 
the substance between the two sides of the leaf, is a very great 
preventive of a succeeding attack taking place; and so also is hand- 
drawing the infested plants, as in both these cases, if the plants or 
pieces of leaf are destroyed with the Maggots in them, we 
necessarily get rid of the flies that they very soon would have turned 
to. But the operations are tedious and expensive, and, unless the 
workers are well looked after, they are almost useless, for if the 
infested plants are left undestroyed, the Maggots within (or many of 
them) will go through their changes without having suffered. Dressings 
of various kinds have been found to do good, but the difficulty has 
been up to the present time how to apply them ; as time does on, it seems 
likely that if the “ Strawsonizer ” should be got to work, that this is 
just one of the kinds of attack to which its work could be usefully 
applied. The deterrent fluid dressings, which would ruin the leafage 
in ordinary hand application, might thus be distributed evenly and 
thoroughly on both upper and under side of the leaves, or, if preferred, 
dry dressings might be similarly applied, and the utter disturbance 
caused amongst the plants (necessarily accompanying the application) 
could not fail to rouse out many of the flies that were amongst the 
plants to receive a share of the dressing. I should greatly hope that 
this would do very much good, but, until then, the best hope seems to 
be in a good hearty growth that will keep the plant well up by supply 
of new leafage more than counterbalancing that which has been 
destroyed by the Maggot-blisters. 
The attack (as is well known) is caused by the fly laying her eggs 
on the Mangold- or Beet-leaves, from which the Maggots creep into the 
leaves, and there feed, causing the well-known great blisters, sometimes 
spreading over several inches of the leaf. They come to full growth 
in about a month, and may then turn to chrysalids in the leaf they 
have injured, or may drop from it to go through the change in the 
earth beneath. The flies appear (in summer) in about a fortnight, so 
that there may be several broods during the warm season; but as the 
Mangold-leaves are much stronger and larger by the time the later 
broods appear, the damage is very much less at this period than when 
the plants are in their first growth. 
The little patches of snow-white eggs do not seem to be often 
