Workers of Great Basin Desert thatch ants (Formica obscuripes Forel) dig simple secondary nests at the base of plants upon which they tend aphids and scales. These secondary nests house only foragers, with the number of foragers occupying each nest positively correlated with the number of worker-tended Homoptera feeding on plant foliage above. Thatch ant secondary nests are cooler than 25 cm below the dome top of the primary nest and maintain a significantly more constant temperature than is observed on the ground surface or in the plant canopy. Thatch ant foragers use secondary nests for at least two purposes: as a cool refuge for Homoptera tenders when midday plant canopy temperatures rise during the summer months, and as the primary place within which Homoptera tenders transfer honeydew to larger "honeydew transporters" for ultimate transport back to the primary nest.
McIver, James D. and Steen, Trygve
"Use of a secondary nest in Great Basin Desert thatch ants (Formica obscuripes Forel),"
Great Basin Naturalist: Vol. 54
, Article 8.
Available at: http://scholarsarchive.byu.edu/gbn/vol54/iss4/8