Hagen. ] 60 [October 23, 
impossible to cheek their visits, which of course were chiefly limited 
to freshly collected or newly spread insects, where the boards were 
left uncovered. Now, every spreading board is fitted to go in a well 
closing box. Nevertheless it is somewhat inconvenient to be always 
sure that every box in the room is always well closed. The injury 
done by moths is always irreparable, as all parts are covered by 
spinning, and boxes once infested by moths I do not consider safe 
before several years have past. As the rooms are now entirely white- 
washed, and, the doors kept closed, are without connection with the 
other rooms of the Museum, I hope to get rid of this pest in the 
future. How important it is to keep the doors of the insect rooms 
closed in a museum, I had the best proof three years ago. A large 
part of the collection was on the gallery in the second story, and the 
door of the lower room was always open. The next large hall was 
filled with stuffed animals and birds, both largely infested, and it 
was thought best to cure them with bicarbonate of sulphur. The 
consequence of this rather severe treatment with this dangerous 
explosive was that actually hosts of the moths indignantly emi- 
grated through the next open door for pleasanter quarters, and fell 
at once upon all the cabinets opposite the door. 
Several years ago I made experiments with this moth. I 
enclosed a certain number with rotten insects in a phial with glass 
stopper, where they propagated year after year. ‘Three years later 
I remarked that the new generation was visibly smaller, and the 
sixth year most of the specimens were scarcely half as large as the 
common size of the moth. But among them I always observed a 
few, one or two, larger ones of the natural size. Of course I had 
added nothing to their food in all those years, so that the diminution 
of the size was probably lack of sufficient food. 
Of other museum pests, two species of Psocus, Atropus divinatorius 
and Clothilla pulsatoria, are exceedingly rare in the collection, thanks 
to our boxes, which are not lined with paper. There is no doubt that 
these insects are very much attracted by paste or glue, and are never 
common therefore in prepared boxes. I think the injury done by 
them is mostly overrated, except where, as in England, insects on 
very short pins are placed in paper boxes. Here, delicate insects, 
Ephemerides, Psocide, Microlepidoptera, are destroyed. In the 
Museum they are so rare that several times when I wanted living 
specimens for study, I hunted without success through many boxes. 
