398 Phylum Arthropoda 



Family mycetophilidae 



CEROPLATINAE AND MACROCERINAE* 



SOME larvae were kept in glass-topped tin boxes (3" diameter by %" 

 high), the bottom of the box being covered about %" deep with cot- 

 ton wool saturated with moisture. On this were placed four or five micro- 

 scopic coverslips, under which the larvae would retreat on being alarmed. 

 The inside of the glass lid was smeared with a thin layer of pure glycerine, 

 which, while fresh, kept the larvae from attaching their threads to the 

 lid. Two larvae were placed in each box. 



Other larvae were kept in the same kind of tins, but on their original 

 bark, as controls on the behavior of those on cotton wool. 



Again, other larvae were kept, with small strips of bark and decaying 

 leaves, between two sheets of glass spaced %" apart. This last method 

 was an attempt to imitate more closely their natural haunts and yet 

 keep them under observation. 



In every case the larvae readily adopted their new surroundings (pro- 

 vided they were kept sufficiently moist), but it was a week before they 

 had spun the usual amount of web, and not until this did they show the 

 sure quickness of movement which is evident when they are accustomed 

 to their surroundings. 



These methods were used for the larvae of Platyura nigrkornis, P. 

 fasciatus, and P. discoloria and, with slight modifications, were also used 

 for rearing other species of these subfamilies. 



The larvae quickly responded to any movement in their web and 

 have not been found to fail to attack anything alive and moving, from 

 the larvae of large chafer beetles to small Collembola. In the field the 

 remains of the following prey have been found in webs of Platyura spp.: 

 Enchytraeus, Myriapoda, Achorutes, other Collembola, Coleoptera, and 

 Miastor. In the laboratory the following prey was offered and accepted, 

 as well as the prey recorded from webs in the field: larvae of Piophila 

 casei and of Scolytus intricatus; %" larvae of Scarabaeidae; Anurida; 

 and free-living nematodes % " long. 



Cannibalism was the invariable result of overcrowding. A space of 

 5 square inches was the least in which 2 larvae were kept without fight- 

 ing, and then cannibalism often occurred. 



The pupal stage was found to be a critical period in the life cycle. 

 About half the pupae in the laboratory were attacked by fungus on 

 pupation and died. Pupae which were disturbed or taken from their 

 webs usually died. 



M. E. D. 



♦Abstracted from a paper in Trans. Ent. Soc. London 81:75, 1933. by G. H. Mans- 

 bridge, Imperial College of Science and Technology. 



