PSYCHE 
Vol. 73 March, 1966 No. 1 
THE HABITS OF PH El DOLE RIDICULA WHEELER 
WITH REMARKS ON HABIT PATTERNS IN 
THE GENUS PILEID OLE 
(HYMENOPTERA: FORMICIDAE) 
By William S. Creighton ' 1 
Department of Biolog} 7 , City College, New York 
During 1965 the writer was able to study seven colonies of Pit. 
ridicula at La Feria, Texas. The observations in this paper were 
made on these colonies or on individuals transferred from them to 
observation nests. There are few North American ants as poorly 
known as Ph. ridicula. When W. M. Wheeler described this species 
in 1916 he had seen three specimens, all majors (1). One of these 
(the type) was taken by C. L. Scott at Brownsville, Texas. The 
other two, in the collection of the U. S. National Museum, came 
from San Diego, Texas, a town about 140 miles northwest of 
Brownsville. Except for these locality records no field data for 
ridicula were available and, as far as can be determined, no additional 
records have been published for this species. 
The nests of ridicula are surprisingly difficult to find and this 
seems to be the reason why the species, which is a door-yard ant in 
the lower Rio Grande Valley, has escaped observation for the past 
fifty years. To judge from the La Feria colonies, ridicula prefers to 
nest in areas where there is a heavy cover of weeds, often nettles, 
common sunflower, Johnson grass and careless weed. These weeds 
not only conceal the nests but also the foragers which come from 
them. During December 1964 I made repeated visits to an area 
where there were two flourishing colonies of ridicula. It is now 
apparent that I often stood directly above these nests but neither was 
discovered until the covering weeds were removed. There are other 
features which make the nests of ridicula hard to find. A mature 
colony of this ant contains at least seventy-five majors and three 
Trofessor Emeritus, City College, New York 
Manuscript received by the editor February 11, 1966 
Published with a Grant-in- Aid of Research from the Society of the Sigma 
Xi. 
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