Carrots and parsnips are liable to have the best-grown root made useless by its being pierced and eaten by the larvæ or grubs of a small fly, known as the _Psila rosæ_. Even the mangel-wurzel, which has been so strenuously recommended as a substitute for the turnip on account of its freedom from insect attacks, and connected with which Curtis only describes a single insect, a leaf-miner, called _Anthomyia Betæ_, upon which he remarks that “these insects will seldom cause any loss to the mangel-wurzel crops should they ever abound to any extent.” In spite, however, of this, we find that the increased growth of this crop has caused a corresponding increase in the insect, to such an extent that, during the last two seasons, many crops have entirely failed from its depredations; as witness the following communication to the _Agricultural Gazette_ for August 23rd, 1862:— My mangel crop was drilled the 17th May, and came up most favourably. On Monday, the 2nd June, I asked my bailiff what was the matter with it; he said, “Oh, it was a sharp frost last night;” but on examination I found that instead of frost the leaves had within them a maggot, which had caused the plant to brown and die off. The late rains and growing weather have enabled the plant somewhat to revive, and also fresh plants to come up (for I had drilled 7 lb. per acre), but found to-day several leaves with maggots in them. My man told me “a quantity had eaten themselves out of the leaf and dropped;” and that he saw “a vast number of sparrows picking up those maggots.” I send you herewith some plants I brought up from the farm. My idea is that the seed was damp and bred the maggots, or that the leaves had been “struck with a fly,” and then the maggot followed. You will please let me have your ideas upon these points.—S. S. The maggot, or larvæ, here described is that of a fly called the _Anthomyia (Pegomyia) betæ_, mangel-wurzel fly. An allied species will sometimes be found on the common dock-leaves, mining their galleries between the dermal cells of the leaves. We have for some time observed the increase of this pest, and we are prepared to state that now we seldom see a crop that is not greatly injured by its attacks. Mr. Curtis thinks that the best method to destroy them is to employ boys to crush the leaves between the thumb and fingers at the part where the larvæ can be seen; and with this we fear we must for the present be content, unless we could devise some means to take the fly before its eggs are laid in the leaves. We need not here dwell at length upon the natural history of those pests of the turnip—the _Haltica nemorum_ (striped flea-beetle), and _H. concinna_ (black flea-beetle), as the nature of their ravages are tolerably well known. Thus much, however, may be said; namely:—