METHODS OF COLLECTING 3 



over the mouth of the funnel above the sample. This heating device may be 

 an electric toaster, stove, or light bulb in the laboratory. In the field where 

 immediate assay of mold is necessary, a frying-pan of live coals or a Thermat 

 pad will give the desired heat. The heat from above will gradually drive the 

 mold animals deeper until they drop through the screens into the alcohol. 

 Although one or two hours will often provide a high yield, two or three days 

 may be necessary. Also, merely allowing the sample to dry in the funnel for a 

 week will give results without the application of artificial heat. 



After berlesing a sample I have found that the yield may be augmented 

 by laying a small square of cloth on the now hot debris and putting several 

 drops of carbolic acid on the cloth and then covering the funnel. 



The Berlese system, in its many ramifications, has one great advantage, 

 that of thoroughness. Where accurate quantitative data are desired it is in a 

 class by itself in making an assay of floor debris. 



Collecting over a period of years has shown that the Pselaphidae are 

 constant constituents of mold. The adults hibernate through the winter in this 

 stratum, copulate therein during the spring and remain active residents during 

 the spring and summer seasons. They are largely nocturnal feeders. Their 

 chief food, at least of the common free-living forms, is the small game that 

 also lives in the mold in such imponderable myriads, insect larvae, the Collem- 

 bola, Acarina (chiefly Oribatidae, Hoplodermatidae and Parasitidae and other 

 minute mites described admirably by Jacot (1935, 1936a, b, c). This general 

 food habit was known to Denny as early as 1825. Since the mold stratum is 

 always at twilight during the day, the period of activity of pselaphids is not 

 circumscribed by intense illumination, although at night many species fly. 



The majority of species of the family have well developed metathoracic 

 wings and fly well, e.g. Bibloplectus, Thesiastes, Rhexius, Rhexidius, Brachy- 

 gluta, Soalenarthrus, Reichenbachia, Decarthron, et cetera. Such forms usu- 

 ally have well-developed compound eyes. Others, such as Rhinoscepsis, 

 have rudimentary wings and rudimentary eyes. The deep mold forms with 

 rudimentary wings, of course, would not be more appreciably collected during 

 the night than through the day, but the night-flying forms can be collected by 

 lights. Light-traps, then, are also useful in obtaining pselaphids. Such traps may 

 be complex or simple. For example, the standard light suspended in front of a 

 sheet, or a lantern on a square of white cloth, will attract many pselaphids. 

 The yield is dependent upon such factors as the type of habitat, season, and 

 particular weather conditions. Both forests and clearings or meadows will 

 yield these insects. Innumerable species fly to lights at night in the tropics, 

 as descriptions of new species attest (Fletcher, 1928). Light collecting was 

 one of my surest methods in the rain forest of Panama. These mold forms 

 often are quite locally distributed. Thus to our perceptions, of two ecologically 

 equivalent, adjacent logs on the forest floor, one log will consistently yield 

 large numbers of Euplectini, whereas the other log berlesed the same length 

 of time may be barren of species. No general statement can be made as yet 

 concerning such local distribution. It may be coincidence; it may be some 



