Termite Nests.An abandoned carton nest was found 41 ft
from the ground in the baldcypress tree from which the excavations were
started. the tree was 1 1/2 ft diam and 68 ft high. Carton material was
found also encircling the base of the tree 1 ft below soil level. Carton
material was found in several other locations in the gallery system but
did no appear to be nesting areas.
The primary nest of the gallery system was found in the sand levee 135
ft southeast of the starting point (Fig. 7). The nest was situated 19
in. below the soil surface and consisted of a carton structure 21 in.
wide by 19 in. high. The nest rested on a layer of cemented carton and
sand. No wood was found near the nest except for some roots of a Chinese
tallow sapling which had evidently grown through the nest after it had
been constructed. No damage was apparent to either the roots or the tree.
The nest was encased within a cemented-sand covering which was about
1/4 in. in thick. The cemented-sand covering and carton material of the
nest were flaked away with a scalpel. The outer 1-2 in. crumbled easily,
but the carton was found to be harder as we progressed toward the center
of the nest. The nest was in concentrically arranged cartonous layers.
Small cavities were found throughout the nest, separated by thin cartonous
Tree Species Attacked.Wood from 4 species of trees, dead
baldcypress, dead pine, live wax myrtle, and live Chinese tallow were
found infested with C. formosanus. Although some pine saplings
were growing in the same area, none was found infested with termites.
Food sources are shown in solid black or in outline if heavily damaged
(Fig. 4, 5, 6). Wood nearest the subterranean nest was the most heavily
damaged. The logs had been reduced to shells and the wood was eaten away
to a series of thin parallel sheets. The pine stump and its root system
in the sand levee were severely damaged above the water table. No carton
material was found in the stump. The cypress tree used as the starting
point for excavations was only moderately damaged. The damage occurred
in the core of the tree and extended up to the abandoned nest 41 ft above
the ground. The cypress stumps 370 ft northwest of the nest also contained
moderate damage in their cores.
The live wax myrtle plants received heavy damage in the roots, at the
bases, and up into the trunks. The roots of the live Chinese tallow sapling
were slightly damaged.
Activity Within the Gallery System.Termite activity was
found in the gallery throughout the period of escavations. Activity decreased
on cold days when temperatures averaged about 4.4° C and on days
when heavy rains occurred. Activity in shallow galleries was most affected
by these changes.
Soldiers and workers were the only forms found in the galleries. When
the galleries were first uncovered, soldiers were most conspicuous. However,
as escavations progressed and galleries neared food sources, the subterranean
termite nest, or terminating points, workers became more numerous. Many
workers were uncovered when the trench around the subterranean nest was
excavated. A positive correlation existed between the size of the gallery
and the termite activity in it.
Six physogastric supplementary queens were found in the center of the
subterranean carton nest. Five of these queens were situated together
in a slitlike cavity 2 in. wide and 1/4 in. high. The 6th queen was situated
in a similiar, adjacent cavity. All the queens were about 14 mm long.
No primary king or queen was found in the nest. Several batches of eggs
were found in cavities near the queens. Soldiers were the dominant form
in the outer layers of the nest, but workers became more numerous toward
the center of the nest. Various nymphal instars were found throughout
the nest, but the younger nymphs were more numerous near the center.
A small group of workers and soldiers was found with a large number
of brachypterous nymphs 15 ft above the ground in the cypress tree at
the starting point of the escavations. A few soldiers were found in the
carton material at the base of the tree.
The pine stump in the sand levee contained a large concentration of
termites. Workers, soldiers, and many brachypterous nymphs were found
in this location. Workers and soldiers were found also in other food
sources associated with the gallery system, including the living trees.
Other Insects Associated with Gallery System.Reticulitermes
Flavipes Kollar was found throughout the excavated area. Its galleries
consisted of small circular tunnels which ran through the clay layer.
These tunnels were never found in the sand. The tunnels measured from
1/16 to 1/8 in. diam and usually were found several inches closer to
the soil surface than were most of the galleries of C. formosanus.
These galleries connected with wood lying close to the soil surface.
At 1 point a series of 3x4-in. cavities, about 6 in. apart which contained
nymphs of various instars was found connected by galleries in close
association with C. formosanus galleries. However, the R.
flavipes was never found in the same galleries with C. formosanus.
On 1 occasion 2 small C. formosanus galleries were traced to
within 1/8 in. of a R. flavipes gallery. On another occasion
a C. formosanus gallery passed within 1/2 in. of a series of R.
flavipes cavities. both species were found in a hollow root that
extended southwest from the pine stump, but they were separated from
each other by a section of the root that contained free water. C.
formosanus termites were found in that portion of the root closest
to the stump. The soldiers of R. flavipes were less numerous
than those of C. formosanus, and they appeared to be less aggressive
Drywood termites, Incisitermes snyderi Light, were found in the
outer 13 in. of the cypress tree where excavation was started.
They were found also existing with C. formosanus in the cypress
logs about 140 ft north of the starting point. However, there was no
evidence that they were occupying the same gallery system.
Ants, Iridomyrmex pruinosus (Rogers); Collembola, Pseudosinella spp.;
Zoraptera, Zorotypus hubbardi Caudel; and a fly Bradysia trifurca (Pettey),
were also found in close association with C. formosanus.
C. formosanus Primary Nest.A small nest containing a primary
king and queen, workers, and soldiers was discovered 200 ft south of
the starting point in a small piece of cypress wood. The queen measured
17.5 mm. long and 4.5 mm diam at the widest portion of the abdomen. Galleries
from this nest were traced to small pieces of wood near the nest. Most
galleries were small, the largest being 1/2 in. wide and 1/8 in. high.
In 1 piece of wood situated 3 ft from that containing the king and queen,
eggs and nymphs wre found in a small carton structure. All the galleries
were traced to their terminating points and there appeared to be no connection
with the main gallery system.
The age of the gallery system can be inferred by correlation with the
fill data. The pumping of fill from the river continued from July 1956
until 1958. The fill used for construction of the sand levee was probably
the 1st soil pumped from the river. Thus, the termite subterranean nest
and galleries could have existed for openly about 10 years, or less.
It is possible that primary reproductives infested a food source above
the water level and once the fill was placed in the area, galleries could
then have been extended into the soil. Although it was impossible to
determine the conditions under which the supplementary queens were produced,
the subterranean nest is believed to have been the central nesting area
of this gallery system. The largest concentration of galleries radiated
from this nest and all the food supplies found within 100 ft of the nest
had received heavy damage. It seems plausible to assume that as food
supplies nearest the nest were consumed, the termites extended their
galleries to new food sources.
The vertical shafts branching from horizontal galleries probably were
used to maintain a constant high humidity in the gallery system. Ratcliffe
and Greaves (1940) reported shafts of this description in galleries of
C. Lacteus. Greaves (1962) also reported finding shafts associated with C.
acinaciformis and C. bruneus Gay. However, none of these species
was reported to construct as many shafts as were found in the gallery
system excavated in our study.
The largest concentrations of shafts wre foundd in areas consisting
primarily of sand which lacked a clay covering. This circumstance was
especially true of the more shallow galleries. Since loose, porous sand
has a high surface evaporation rate, the shafts probably served to constantly
infuse moisture into the horizontal galleries. In areas where a clay
covering was present, there were fewer vertical shafts. In these areas,
the clay apparently served as a "lid," slowing the surface evaporation
Greaves (1962) reported that galleries of C. brunneus in sand were constructed
as slits in tubes of cemented sand. He surmized that by cementing the
sand around each gallery the termites might aid in preserving a high
humidity within the galleries. The thick cartonous lining around the C.
formosanus galleries running through loose sand also probably served
this same function. In addition, the thick lining and elliptical shape
of the galleries probably added strength to the gallery structure.
The gallery depth varied with the thickness of the clay cover. Where
no clay layer was present, the galleries ran deep. Galleries were seldom
constructed in clay. In forming galleries in soil, termites do not remove
the soil to a great extent but compress it away from a central starting
point, forming a compact layer around each gallery (Greaves and Florence
1966). Ebeling and Pence (1957) reported that in moist sand termites
excavate by pushing their heads forward, then pressing the sand particles
to either side. The smaller particles are taken into the buccal cavity
and placed along the walls of the tunnel to form a smooth and titly sealed
surface. The fact that termites do not necessarily remove the soil in
gallery construction but compress it to the side by pushing their heads
forward could, in part, explain why C. formosanus rarely extended
its galleries into the clay. However, galleries of R. flavipes were
found running not in the sand but through the clay.
Depth, size, and shape of C. formosanus galleries, as well as
the number of vertical shafts extending to the water table, probably
depend on edaphic factors such as soil moisture, soil gases, and soil
We believe that the small, unlined galleries branching from the larger
galleries, were for explorations. Indications are that the entire gallery
area was explored by subterranean tunneling. Several times during gallery
excavation, traces of smaller galleries were found running through larger
operative galleries. Probably when contact had been made with a new food
supply a larger gallery was directed through the smaller gallery. A succession
of consumed food supplies encircled the subterranean termite nest. From
these food sources radiated other galleries, including numerous exploratory
galleries. This fact indicates that C. Formosanus expand their
gallery system by moving from 1 food supply to another; first by means
of smaller galleries to locate food supplies then enlarging them to accomodate
increased activity. Ratcliffe and Greaves (1940) and Gay (1946) have
suggested the possibility that surface scouting plays some part in the
discovery of food by C. lacteus and C. frenchi.
The most conspicuous form in the galleries when they were first uncovered
was the soldier caste, probably because of the defensive function of
this caste. Large numbers of workers were later found as galleries terminated,
neared food sources, or the subterranean nest. It is postulated that
the workers were probably retreating as gallery excavation advanced.
We thank R.J. Gagne and A.B. Gurney, Entomology Research Division, USDA,
Washington, D.C., and M. Kyle, Entomology Department, Louisiana State
University for determining insect species; J. H. Roberts, Entomology
Department, Louisiana State University and Stanley McKenzie, McKenzie
Pest Control, Lake Charles, LA., for photography: and William Iglinsky,
Biology Department, McNeese State College for his assistance during this
investigation in Lake Charles.
Ebeling, W., and R. J. Pence. 1957. Relation of
particle size to the penetration of subterranean termites through barries
of sand or cinders. J. Econ. Entomol. 50: 690-2.
Ehrhorn, E. M. 1934. The termites of Hawaii, their economic
significance and control and the distribution of termites by commerce,
p. 321-33. In Kofoid et al. [ed.] Termites and Termite Control.
2nd ed. University of California Press, Berkely. 1946. A case of
house infestation by a tree dwelling colony of Coptotermes frenchi Hill.
J. Counc. Sci. Ind. Res. Aust. 19: 330-4.Greaves, T. 1959.
Termites as forest pests. Aust. Forest. 23: 114-20.
1962. Studies of foraging galleries and the invasion
of living trees by Coptotermes acinaciformis and C. brunneus (Isoptera).
Aust. J. Zool. 10: 630-51.Greaves, T., and R. C. Florence. 1966.
Incidence of termites in black-butt regrowth. Aust. Forest. 30:153-61.
Kalshoven, L. G. E. 1941. Groundplans of termite nests. Entomol.
Med. Ned.-Indie. 7:30-34.
Ratcliffe, F. N. and T. Greaves. 1940. The subterranean foraging
galleries of Coptotermes lacteus (Froggatt). J. Counc. Sci. Ind.
Res. Aust. 13: 150-61.
Reprinted from the
ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA
Volume 62, Number 3, pp. 536-542,
1 Isoptera: Rhinotermitidae [Return
2 A portion of a thesis by the senior
author to be submitted to the Graduate Faculty of Louisiana State University,
Baton Rouge, in partial fulfillment of the requirements of the degree
of Master of Science in Entomology. This study was supported in part
under a study plan FS-50- 2201-0.504 with the Wood Products Insect
Laboratory, Southern Forest Experiment Station, United States Forest
Service, Gulfport, Miss. Accepted for publication June 3, 1968. [Return
3 Research Assistant
and Professor of Entomology, respectively, Entomology
Department, Louisiana State University, Baton Rouge.
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