GENERIC DIVERSITY IN PHASE OF RHYTHM 
IN FORMICINE ANTS 
By E. S. McCluskey 
Departments of Physiology and of Biology 
Loma Linda University, Loma Linda, California 92354 
Ants are abroad through most of the day and night. But the 
species composition of this 24-hour patrol changes from one part of 
the day to the next (Talbot 1953; Wilson 1971). For example, in 
Michigan the maximum foraging activity of Lasius neoniger is at 
night, of Myrmica americana in the early morning and late after- 
noon, and of Formica pallidefulva nitidiventris in the middle of the 
day (Talbot 1946, 1953). 
Likewise the mating flights of ants occur at different hours for 
different species (Kannowski 1963; Talbot 1945). The flight times 
may be similar for closely-related species (Kannowski 1959a). 
If one were to look at many species of one genus, would he find 
them to be similar as to time of day of foraging or of mating flight? 
Or does each genus span the 24 hours in terms of its various species? 
The aim of this report is to quantitatively compare species diversity 
with generic diversity of such phase relationships in one tribe of ants, 
the Formicini. The biosystem atics of much of this group, particu- 
larly of the genera Lasius, Acanthomyops, and Formica, is relatively 
well known on morphological and zoogeographic grounds (Wilson 
and Regnier 1971). 
The comparisons are based on a compilation of literature records 
for as many species and genera as possible in this tribe (Figs. 1 and 2). 
A genus was included if there were records for three or more species. 
About a third of the species of Acanthomyops, of Cataglyphis, of 
Lasius, and of Myrmecocystus are represented in the records cited 
here, but a smaller fraction of the large genus Formica. These 
genera are all from North Temperate latitudes. (For a preliminary 
report see McCluskey, 1972.) 
The workers could be classified as nocturnal, diurnal, etc. But in 
the absence of single or definite beginning points or midpoints of 
activity in most of the literature records, another method was used 
to reduce each rhythm to one point for comparison with other species: 
If the ants do not normally come above ground at all (e.g., Acan- 
thomyops species), the species is plotted as an X at the extreme left 
(Fig. 1) ; if nocturnal only, one position farther to the right; if out 
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