LIBRARY

HYMENOPTERA 671
The important facts concerning a nest or formicarium may be summarized
as follows:
1. Queens once fertilized reproduce almost continuously in the tropical and
subtropical regions and cease only during the colder season in their most
northerly and southerly limits. They have been known to live at least
15 years.
2. Workers enlarge and maintain the nest, gather the food, feed and nurse the
queen and young, and defend the formicarium.
3. Colonies may continue to increase in size for many years. The population
may vary from a few thousands up to 500,000 (Forel 1874, Wheeler
1926).
4. Nests are of many types and variously located. Those of most species
consist of excavated galleries, chambers, and habitations in the soil.
The excavated materials, leaves, and other plant debris may be heaped
around or near the entrances, forming craters or mounds. Nests of
Formz'ca rufa may attain a height of from 2 to 5 ft. and a diameter of
from 3 to 8 ft. Such mounds not only cover and protect the subterranean
galleries but are themselves inhabited. When disturbed, certain
of these mound-building species discharge sufficient quantities of formic
acid to form a vapor that makes the immediate vicinity very uncomfortable
for man and other mammals. Nests may also be established in
stems, seeds, leaf petioles, thorns, and tied leaves of living plants and
in hollow twigs, dead galls, logs, and stumps. They may be made of
paper.like materials and attached to and suspended from trees, rocks,
and other objects. Certain species nest in or in close proximity t.o the
nests of other species as, in the case of Leptothorax emersoni Wheeler, in
the nests of Myrmica spp. in eastern North America. Such relationship
in compound nests is called plesiobiosis by Wheeler.
FOOD
Ants are for the most part general feeders and consume both animal and
vegetable food either as solids or liquids. Their food habits may be briefly
summarized as follows;
1. Carnivorous - especially members of the subfamilies PONERINlE and
DORYLINlE, but members of other subfamilies also feed on animal
matter. They feed on insects, spiders, and other small invertebrates
and rarely also upon small and even large mammals which are overwhelmed
and killed.
2. Herbivorous - includes members of all groups except the two carnivorous
subfamilies mentioned above. These ants feed upon seeds, coatings of
seeds, fungi, fruits, and other vegetable products.
3. Omnivorous - members of the higher groups DOLICHODERIN.tE,
FORMICINJE, and MYRMICINlE which, while largely vegetarians,
also feed upon live and dead animal matter that may be available. They
are also very fond of the nectar of flowers and other sweet glandula!."