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Dorymyrmex
insanus (Buckley)
Figures 104-106
Formica insana Buckley, 1866:165;
o _. Wheeler, 1902e:6-7.
Dorymyrmex insanus: Norton,
1873:734. McCook, l879:185-186. Snelling, 1995:1-5.
Dorymyrmex pyramicus: Wheeler,
1902e:6-7. Cole, 1942:371; o. Creighton, 1950:348?349; pl. 47; o
_ _. Cole, 1957:130; o. Wheeler and Wheeler, 1963:155?157; map 27;
o _ _. Cole, 1966:18. Wheeler and Wheeler, 1973:103, 105?106; fig.
39; o _ _.
Conomyrma (C.) pyramicus:
Kusnezov, 1952: 430 (in part). Wilson, 1964:10.
Dorymyrmex (Conomyrma)
pyramicus: Gregg, 1963:432?434; map; o.
Conomyrma insana: Snelling,
1963:4-5; o _. Wheeler and Wheeler, 1977; 2, 3. Allred, 1982:459?460.
Wheeler and Wheeler, 1986:57-58.
RANGE: Central Texas
west to California; adjacent Mexico.
DESERT RECORDS. Map
5. Ubiquitous, but sometimes displaced
locally by D. bicolor; 99 records.
DISCUSSION. There are
a number of entirely black species of Dorymyrmex in the United
States, and for many years the identity of D. insanus was
in limbo because no type material of D. insanus was known
to exist. In a misguided effort to settle the identity of D. insanus,
a neotype was designated by Johnson (1989). That designation was
shown to be invalid by Snelling (1995) and an appropriate neotype
was designated.
In the field this ant can
be confused only with the small, monochromic Myrmecocystus.
The two have very different ways of running, however. The Dorymyrmex
tend to be quite direct and even-gaited, in contrast to the usually
erratic and "jerky" running of Myrmecocystus. Of
course, too, Dorymyrmex, when crushed is easily identified
by its decidedly unpleasant odor.
Habitats for this ant are similar
to those for D. bicolor. Dorymyrmex insanus occurs
at elevations between -190 and 5800 feet. Nests are situated in
exposed areas, but sometimes are found near, or partially under,
large shrubs such as Creosote Bushes. The craters are small, 5-10
cm in diameter, circular to irregular in shape, often much higher
on one side (Fig. 312).
This species moves rapidly
while foraging. Workers were observed foraging in afternoon hours
during the spring, evening hours during the warmer months of July
-September and during early afternoon in October and November. They
appear to estivate during winter months, at least on the Mojave.
Honeydew is collected from
aphids, mealybugs and other scale insects, which the ants tend,
and workers have been noted taking nectar from Cercidium floridum,
Sphaeralcea ambigua, Chrysothamnus paniculatus, and Opuntia
bigelovii. Highly predaceous, workers have been found to take
a wide array of arthropods, such as termites, larval Lepidoptera,
syrphid flies, small beetles, chalcidoid wasps and other species
of ants. This species has been observed to attack much larger ants,
such as Aphaenogaster cockerelli, that trespass near their
foraging columns (Cazier and Statham, 1962). Debris from one nest
alone consisted of fragments of 732 ants representing five different
genera: Pheidole, Crematogaster, Monomorium, Solenopsis,
and Paratrechina (reported as Nylanderia) (Hung, 1974).
It is not known whether these were scavenged from other nests or
represent freshly killed prey.
Alate females have been collected
at black lights during the month of May.
The lizard, Phrynosoma mccalli,
is known to be predaceous upon D. insanus.
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