SCALE INSECTS
These appear much less in collections now than formerly, because the old large specimens are replaced by young and vigorous plants. Thirty or forty years ago, it was a usual thing to spend several days every year scraping the brown scales from tall plants of Aërides odoratum, Vanda tricolor, and other specimen Orchids, and what was called "cleaning" was going on all the year round. Now there is much less need of such work, although scale will appear in its various species on one section of plants or another. In the periodical inspections, all plants attacked by it should have the insects removed by a piece of stick blunted at the edge and point, sponging the leaves afterwards with some diluted insecticide. Syringing with an insecticide, or dipping the plants in the liquid, should be avoided, for the quantity applied is likely to saturate the material in which the plants are potted and to run into the centres of the young growths and cause injury. By means of a sponge, it may be applied lightly or heavily, but the operator has command in each case over what he is doing.