[Carbolic Acid.]—Mr. A. T. Marshall (Entomologist's Monthly Magazine, Dec., 1873, p. 176) records that he washes the paper of his boxes with the common disinfecting solution of carbolic acid in two-thirds water, which dries without staining and protects the specimens from Psoci.
[A Means of preserving Insects in dry hot Countries.]—In the “Horæ Societatis Entomologicæ Rossicæ,” XXIV, pp. 233, 234 (1889), M. A. Wilkins, writing from Tachkent in Turkestan, alludes to the inefficiency of ordinary preservatives in Central Asia, on account of their rapid volatilization through the hot dry air, so that if a collection be neglected for only two or three months Anthreni are sure to be found in the boxes. He has hit upon a plan which he finds effective, and at the same time very simple. He employs India-rubber bands about 1½ inches in width and less than the length of the boxes to which they are to be applied. These bands are stretched over the opening line of the boxes, and effectually prevent the entrance of the most minute destroyers. Possibly a similar plan might be adopted in other countries with a like climate. At any rate, the method has the merit of extreme simplicity. (The Ent. Mo. Mag., Apr., 1891, p. 107.)
MOLD.
Collections kept in damp places or in a moist climate are very liable to mold, and under such conditions it is difficult to avoid this evil. Carbolic acid is recommended, but Mr. Ashmead, who has kept a large collection in the moist climate of Florida, has found the use of naphthaline much more satisfactory. Mr. Herbert H. Smith who has had more extensive experience in the tropics prefers the carbolic acid. Moldy specimens may be cleansed by washing with carbolic acid applied with a fine camel's hair brush.
[VERDIGRISING AND GREASING.]
The action of the acid juices in the bodies of certain specimens—as many of the Lepidoptera, Coleoptera, and Diptera—will cause the formation of verdigris about the pin, which in time accumulates and disfigures and distorts the specimen, and ultimately corrodes the pin, so that the slightest touch causes it to bend or break. There is no preventive yet known for this trouble other than the use of pins which have no brass to be corroded. Japanned pins are made for this purpose, and are, on the whole, satisfactory, but they bend easily and some caution is required in handling them. In place of these pins, which are somewhat more expensive than the steel pins, iron pins may be used. These are very soft and bend too easily for satisfactory use. The steel pins may be rendered available for use by an immersion in a silver bath, which is comparatively inexpensive.
Insects the larvæ of which live in wood are particularly subject to verdigris, as the Cerambycidæ and Elateridæ in Coleoptera, the Uroceridæ in Hymenoptera and Sesiidæ in Lepidoptera. In Hymenoptera the families Formicidæ, Mutillidæ, and the endophytous Tenthredinidæ verdigris very rapidly, and most Diptera also. With all these insects japanned or silvered pins should be used, or when not too large the insects should be mounted on triangles. This verdigrising is associated with what is known as greasing, and this, as just indicated, is also associated with endophytous larval life. The verdigris may be prevented by the methods indicated, and I would strongly advise, as a good general rule to be followed, the rejection of the ordinary pins for all species which, in the larva state, are internal feeders. But there is no way of preventing greasing or decomposition of the fats of the body, which may affect a specimen years after it has been in the cabinet. If the specimen is valuable the grease may be absorbed by immersion in ether or benzine, or by a longer treatment with powdered pipe-clay or plaster of Paris. Insects collected on seabeaches, and saturated with salt water, also corrode the common steel pin very quickly and should be mounted on japanned pins. It is also advisable to rinse such specimens thoroughly in fresh water before mounting.
The conviction has been forcing itself on my mind for some time that the naphthaline cones tend to promote greasing and verdigris, and carbolic acid in some small vessel secured to the cork, were, perhaps, preferable.