Doubtless a centrifugal drying machine might be successfully used for this purpose in summer.  Pickled alewives, freshened out in water, have been found to answer fairly well, when other materials are lacking, at least to give growth to maggots otherwise started.  Fish pomace has not thus far given satisfaction, but seems worthy of further trial.

It is commonly necessary to expose meat but a single day to obtain sufficient fly spawn; the larvae are hatched and active the next day, except in cool weather, and they attain their full growth in two or three days.  To separate them from the remnants of food and other debris was at first a troublesome task.  It is now effected as follows:  the meat bearing the fly spawn is placed on a layer of loose hay or straw in a box which has a wire-cloth bottom, and which stands inside a slightly larger box with a tight wooden bottom.  When full grown the maggots work their way down through the hay into the lower box, where they are found nearly free from dirt.

When young salmon or trout first begin to feed they are quite unable to swallow full-grown maggots.  Small ones are obtained for them by putting a large quantity of fly spawn with a small quantity of meat, the result being that the maggots soon begin to crowd each other and the surplus is worked off into the lower box before attaining great size.  No attempt is, however, made to induce the young fish to swallow even the smallest maggots until they have been fed a while an chopped liver.

In the above methods maggots are produced and used in considerable numbers, sometimes as many as a bushel in a day.  Through September, 1893, although the weather and some other circumstances were not very favorable, the average daily production was a little over half a bushel.

They are eagerly eaten by the fish, which appear to thrive on them better than on dead meat.  Having great tenacity of life, if not snapped up immediately by the fish they remain alive for a day or two, and, as they wriggle about on the bottom, are almost certain to be finally eaten; whereas the particles of dead flesh that fall to the bottom are largely neglected by the fish and begin to putrefy in a few hours.  In the fish troughs there are, therefore, certain gains in both cleanliness and economy from the use of maggots which may be set down as compensating the waste and filthiness of the fly-house.

As the growth of maggots can be controlled by regulation of the temperature, it is possible to keep them all winter in a pit or cellar, and advantage is taken of this to use them during winter as food for fish confined in deep tanks not easily cleaned.

The offensive odors of decaying flesh may be largely overcome by covering it, on putting it away in the boxes, after the visits of the flies, with pulverized earth, and it is not improbable that by this or some other method the business may be made almost wholly inoffensive, but in its present stage of development it is too malodorous to admit of practice in any place where there are human habitations or resorts within half a mile of the spot where the maggots are grown.