But by far the most dangerous enemies of insect collections are the larvae of some half dozen or more species of Dermestidae belonging to the genera Anthrenus, Attagenus, Trogoderma, and Dermestes. Of these _Anthrenus varius_ is the more common pest, in museums, especially in the North and East. In the South and West _Trogoderma tarsale_ and _T. ornatum_ (?) replace Anthrenus. The European species _Anthrenus musaeorum_, is, on the authority of Hagen, rare in this country, and probably occurs chiefly in collections of imported insects. It is the common injurious species of Europe. _Anthrenus scrophulariae_ (see Fig. 67) occurs also in collections, Dr. Hagen stating that he has found it nearly as common as _A. varius_, and certainly more dangerous. In my own experience it is rarely found in insect collections. Two species of Attagenus (_A. pellio_ and _A. megatoma_) have also been found in collections. _A. megatoma_ has been found by Dr. Hagen to do not a little damage to insect collections in Cambridge, as well as to equal if not exceed the Carpet Beetle in its disastrous attacks upon carpets and household furniture. The other species, _A. pellio_, is rarely found in this country, but is much more common and obnoxious in Europe than _A. megatoma_. _Dermestes lardarius_ is sometimes found in collections, and is attracted by the presence of animal matter such as skins, etc. The two particularly destructive pests, as pointed out, are _Anthrenus varius_ and _Trogoderma tarsale_. These species, together with most of the others, have no definite breeding period, but, in the uniform temperature of the laboratory or museum, breed all the year round and present no definite broods. It is the experience at the Museum that the boxes on the lower tier of shelves are very much more subject to attack than those on the upper tiers, from which it would seem that the parent beetle deposits her eggs outside the boxes on the floor of the cases and that the young larvae work their way into the smallest crevices. The danger of infection by these pests is greater in warm climates like that of Washington than in regions further north, as the warm season begins earlier, lasts longer, and furnishes better conditions for breeding and multiplication. [Illustration: Fig. 122.--A naphthaline cone.] REMEDIES.--The following remedies and preventives will prove efficient in checking or preventing the work of these pests. _Naphthaline._--Where tight boxes are employed little fear of the work of these destructive agents need arise, especially if the boxes are kept supplied with repellent naphthaline cones. These are hard cones of naphthaline, mounted on pins for convenient placing in the boxes (see Fig. 122), and may be obtained of dealers in entomological supplies. Naphthaline cones act as repellents to these insects and also to some extent retard the development of the larvae in all stages and particularly of the eggs.