1963] 
Evans — Cephalonomia 
163 
determined morphs; they are, however, “fortuitous castes”, depending 
upon the nature of the host rather than upon food provided by adults 
of the same species. Perhaps the term polyphasy is more applicable to 
such cases, and the term “phase” better than “morph”. 
In the case of Cephalonomia perpusilla , there is no way of knowing 
at the present time whether the various forms are determined geneti- 
cally or as the result of the influence of hosts of different sizes and 
species. John F. Lawrence writes that most of the fungus samples 
from which these bethylids were reared contained several species of 
ciids (up to six). However, the samples from Mexico, all of which 
were from Ganoderma rather than the more usual Polyporus and 
FomeSj contained only one or two species of ciids, and these ciids were 
only 1 mm. long or less. Thus the smaller size and greater degree 
of winglessness of the Mexican material might reflect these smaller 
hosts. The rearing of this species in series from specific hosts would be 
difficult but not impossible, and it is the only way in which these 
questions can be answered. 
References Cited 
Bridwell, J. C. 
1920. Some notes on Hawaiian and other Bethylidae (Hymenoptera) 
with descriptions of a new genus and species. Proc. Hawaiian Ent. 
Soc. 4:291-314. 
Kearns, C. W. 
1934. Method of wing inheritance in Cephalonomia gallicola Ashmead 
(Bethylidae: Hymenoptera). Ann. Ent. Soc. Amer., 27:533-541. 
Richards, O. W. 
1939. The British Bethylidae (s. 1.) (Hymenoptera). Trans. R. Ent. Soc. 
London, 89: 299-305. 
Salt, G. 
1937. The egg parasite of Sialis lutaria: a study of the influence of the 
host upon a dimorphic parasite. Parasitology, 29 : 539-553. 
1952. Trimorphism in the ichneumonid parasite Gelis corruptor. Quart. 
Jour. Microscr. Sci., 93:453-474. 
Schmieder, R. G. 
1933. The polymorphic forms of Melittohia chalyhii Ashmead and the 
determining factors involved in their production (Hymenoptera: 
Chalcidoidea, Eulophidae). Biol. Bull., 65:338-354. 
