1963] 
Evans — Cephalonomia 
161 
males came to be winged or wingless in about a 1:3 ratio, the females 
winged or with wings reduced or absent in about a 1 13 ratio ; further- 
more the females came to show a distinct zonation with respect to 
wing-length types, the short-winged forms being entirely replaced by 
apterous forms at the periphery of the range. The actual figures are 
shown in Table I, where one notes with regret the absence of any 
records of males from zones A and B as well as far too few females 
to be sure of the present situation in the center of the range. 
These 1 13 ratios suggest simple Mendelian inheritance, wingless- 
ness being dominant. I doubt very much if the situation is that simple. 
One notes, for example, that in the 69 available Mexican females, the 
winged : wingless ratio is 1 19. In the absence of careful sampling 
techniques and reared series, one simply cannot be sure what is hap- 
pening. The genetics of perpusilla may not be radically different from 
that of gallicola as described by Kearns (1934), although clearly it 
is not quite the same for the characters of the female, since this sex 
is always apterous in gallicola . 
One wonders if there is some particular selective advantage in wing 
dimorphism in these very small wasps. I have no new data bearing on 
this subject, but I suggest that this phenomenon may be related to 
the unusual mating behavior of these insects. Several persons have 
reported that in Cephalonomia and other gregarious Bethylidae the 
males emerge first and chew their way into the cocoons of the females 
(often their own sisters), fertilizing them before they emerge. This 
would result in much inbreeding unless males also flew about and 
mated with females elsewhere (since the females do mate again after 
emerging) . The presence of two type of males, one fully winged and 
the other completely wingless, might be a mechanism for insuring that 
both inbreeding and outbreeding would occur. The same result would, 
of course, be achieved by alate males alone if they first mated with 
their sisters and then flew about and mated with other females, but 
there may be behavioral or ecological reasons why this is ineffective. 
It should be born in mind that these minute insects do not “fly” in 
the usual sense of the word. Their wings are slender and fringed with 
long setulae, and the venation reduced to a single short vein at the 
base of the fore wing. It seems quite certain that such insects are 
incapable of much sustained, directed flight, but after becoming air- 
borne are merely wafted about by air currents. Since these wasps are 
restricted to fungi infested with ciid beetles, their available habitat is 
broken up into widely separated, strongly localized sites. The chances 
of a winged male alighting on (1) a fungus of suitable type, (2) in- 
