742 CHARLES PAuL ALEXANDER 
are working may be brought into the laboratory and placed in the breed- 
ing cages. This method may be followed with species of Tanyptera, 
Ctenophora, and other genera. 
Fungicolous species, as a rule, also are easily reared. The entire fungus 
in which the specimen is found should be brought into the laboratory 
and placed in a jar on a bed of clean sand. The sand takes up the liquids 
produced by the disintegration of the fungus and provides a place for 
pupation. Species of Limnobia, Ula, and other forms are reared in this 
manner. 
The chances for error in rearing are many. One must be certain that 
there are no other larvae in the breeding jar with the one that is being 
reared; else one of these other larvae might transform and emerge first, 
and the results would be altogether misleading. The writer has had 
this happen in his breeding cages, even after the utmost care had heen 
used to guard against it. Beling, the great German student of the 
immature stages of crane-flies, made a few mistakes in the same way; 
as, for example, in the case of his Trimicra, the larvae that he describes 
being pediciine and probably a species of Dicranota or the young larvae 
of a Tricyphona. What happened, presumably, was that Beling found 
~ these pediciine larvae and placed them in rearing; in the same cage, bu! 
unknown, to the breeder, was a larva of Trimicra which emerged, and 
naturally Beling thought it came from one of the larvae that he had 
placed in rearing. It is usually easy to check up such errors. Thus, 
the writer has placed in rearing the larvae of Penthoptera and, to his 
surprise, had adults of Iamnophila adusta emerge. Obviously larvae 
of L. adusta got into the cage in spite of precautions, and emerged first. 
When closely related species are concerned, however, it becomes a hard 
matter to straighten the tangle. Hence a species cannot be reared too 
many times, since each rearing checks up the previous results. j 
The precaution to be taken in’ the case of mud-inhabiting or sand- 
inhabiting species is to see that the mud or sand is baked or thoroly 
desiccated in order to destroy all life in it. Then it may be remoistened, 
and the larva or larvae chosen to rear may be put into the earth without 
the chance that some unknown larva may be lurking in the medium and 
may emerge first, and so bring about confusion. j 
The writer has found that the most satisfactory way to rear small 
tipulid larvae found in earth or sand is to place a small amount of baked 
