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Winged adult termites (about % of an inch long)
are feeble fliers and soon lose their wings.
BULLETIN OF THE CONNECTICUT AGRICULTURAL
EXPERIMENT STATION, NEW HAVEN • NO. 695, OCTOBER 1968
Digitized by the Internet Archive
in 2011 with funding from
LYRASIS members and Sloan Foundation
The increase in numbers of Connecticut buildings infested by
termites which occurred in the early 1930's prompted study and
investigation of the situation. Examination of buildings disclosed
that termites were present in many, and that damage was occur-
ring. Their means of entry was determined, and both preventive
construction and soil treatment studied and tested.
Results of these studies were published in Station Bulletin 382
and in articles in scientific journals and Reports of The State
Entomologist. All are out of print.
When the new soil insecticides were introduced about 20 years
ago, their effectiveness was determined in practical tests. Studies
on means of entry have continued, with emphasis on the new
types of construction in use.
This publication has been prepared as a report on all of this
work. Staff members are available to identify insects believed
to be termites, and to examine specimens of wood for signs of
Information collected originally by J. F. Townsend, Neely
Turner, M. P. Zappe, J. Peter Johnson, and W. T. Brigham is in-
cluded in this Bulletin.
TERMITES IN BUILDINGS
The only species of termite established in Connecticut is the eastern
subterranean termite (Reticulitermes flavipes K. ). These termites nest
in the ground, and were certainly present long before the area was
colonized. From time to time other species of termites, usually drywood
forms that nest in the wood and not in the ground, have been brought
into the state in furniture or picture frames. To the best of our knowl-
edge, none of these exotic species has become established. It is doubtful
if any of these, which are found in the tropics, could survive in this
climate except under very unusual circumstances.
Termite damage to buildings was recorded near Boston, Massachusetts,
as early as 1875, and in Connecticut in 1909. Between that first state
report and 1931, only three infested buildings were reported. In 1932
there were seven; 1933, thirteen; and 1934, twenty-four. Since that time,
the number of infested buildings reported has varied from year to year,
but has always been large enough to confirm that termites are major
pests in Connecticut.
The cause of this change has been the subject of a great deal of specu-
lation. Certainly termite damage can be misidentified as rot, and possibly
this happened in the early days. The installation of central heating sys-
tems allowed the termites to be active during the winter. But the major
factor seemed to be changes in architecture. The "old colonial house"
was built on stone foundations and usually close to the ground. This
made it very susceptible to entry by termites. Fashions changed, and
most dwelling houses were built on brick foundations which extended
well above the surface of the ground. Porches in both cases were wooden.
About 1920, the style changed and the "modern colonial" was adopted.
Foundations were concrete, but the structure was close to grade, and
the earth- or cinder-filled concrete porch or terrace was a common fea-
ture. The construction of these porches was such that termites found
easy access from the fill to the wooden framework of the house. The
termite "outbreak" of the 1930's could be attributed to this single factor.
At that time, housing developments on cultivated farm land showed in-
festations only in the buildings constructed where farm buildings had
existed, or along the site of a farm fence with wooden posts.
Since World War II the modern colonial has remained in vogue, and
the ranch-type has been added. This more recent stvle is built just as
close to the ground as the colonial, and also has the same concrete
porches and terraces with the same easy access to termites. Moreover,
the woodlands, once avoided for development, have become preferred.
Since the woodlands are the natural home of termites, more infested
dwellings are to be expected.
Connecticut Experiment Station
Damage Caused by Termites
Hundreds of buildings have been examined carefully for termite dam-
age. Only one dwelling house has been found so badly damaged as to
cause concern about its structural safety. Two other houses had very
extensive damage, and in the recent past had been strengthened by
auxiliary columns. All these houses were more than 150 years old. In
newer buildings, there was seldom any sign of serious structural weak-
Estimates of damages in dollars are difficult to make and defend. The
cost of the wood consumed is usually very small, but the expense of
removing and replacing it with sound wood is high. The cost of control
by use of insecticides is relatively high.
Biology of Termites
Termites are social insects, and have castes or forms specialized for
the work of the colony. The fertilized female or queen lays the eggs. The
blind and sexless workers, which are white and live entirely under cover,
care for the eggs, feed the young and the queen, and do the work of
the colony ( Figure 1 ) . The soldiers, which have very large heads and
jaws, guard the members of the colony against attacks by other insects,
Figure 1. Termite workers, soldiers, and supplementary queens,
shown about one and one-half times life size.
Termites in Buildings 7
The colony does not occupy a defined space with recognizable perma-
nent chambers and runways. It is usually located below the frost line
and in moist but not wet soil. A colony is produced very . slowly, until
for reasons not yet understood some supplementary queens are devel-
oped. The eggs produced by these queens will develop into mature males
and females. When these molt for the last time, they are black and have
four wings (Cover photo). They escape from the colony in a sort of
swarm and emerge into the light. After a brief but aimless flight the
wings are shed and the males and females mate. They attempt to start
a new colony in soil not occupied by the original colony. Flights occur-
ring in houses are usually of no significance other than as an indication
that the building is infested.
Worker termites construct runways in all directions in search of food.
The principal food is cellulose, which is digested by the aid of protozoa
in the digestive tract. In the woodlands where they lived naturally be-
fore the settling of the country, their food was mostly limbs and twigs
falling from living trees, or an entire dead tree. They may attack dead
roots of living trees. Infestations have been found in living geraniums,
strawberries, phlox, and other plants with a large crown, from time to
time. In infested buildings, they have fed on paper and books, fabrics
It is obvious that a single worker termite, less than a quarter of an
inch long, cannot consume much wood at a time, and cannot make very
many trips from the colony to wood in buildings in a single day. Thus
serious damage to buildings is the result of years of feeding by a large
colony or colonies.
How Termites Enter Buildings
Termites may enter buildings ( 1 ) through direct contact between the
wood and the soil, (2) through cracks or hollows in masonry and con-
crete foundations, or (3) through covered shelter tubes which they
build over the face of masonry foundations for short distances ( Figure 2 ) .
Direct contact between wood and soil is by far the most common
means of entry in Connecticut buildings. Sills in contact with the fill
under concrete porches and terraces (Figure 3); wooden supporting
posts, partitions, and steps built in basements before concrete floors are
poured; and wooden hatchway, steps, porches, and even basement win-
dow frames offer such direct contact. In more than half the infested
modern dwellings in Connecticut, the termites have entered through
filled masonry porches and terraces.
Entry through cracks or hollows in foundations is less common but
does occur. This means of entry has been more common in older build-
ings with stone foundations than in modern structures. Masonry block-
foundations are also vulnerable.
Entry through shelter tubes built up over foundations is possible but
seems relatively rare. It is most likely to occur when large quantities of
wood are buried in the fill near the foundation. It is much more common
for termites to construct tubes down from infested wood, possibly to
gain more direct access to the soil.
Connecticut Experiment Station
Figure 2. Termites constructed this shelter tube from wood to the
ground in a partly excavated area, formerly an exterior wall.
There is no record of establishment of a termite infestation in a house
from infested fireplace wood or lumber. It is possible that this could
occur, but very unlikely.
Finding Termites in Buildings
The occurrence of swarms of winged termites may be the first indi-
cation that a building is infested. Such swarms may occur as early as
January, in heated houses, but are more common in February and March.
They may take place as late as July indoors. Out of doors, the swarms
usually occur between the middle of April and August first. In buildings,
the termites appear from a crack either in the floor or woodwork. They
come out rather rapidly for several minutes, and then disperse. These
winged adults may be killed easily by any household insecticide spray
or aerosol if they occur in sufficient numbers to be a nuisance.
Winged ants of about the same size as termites may also emerge in
Termites in Buildings
Figure 3. Direct contact between the sill and the earth fill under masonry
porches or steps in an invitation to termite infestation. Part of the masonry
floor has been removed to make repairs.
houses. The ants are wasp-waisted; termites do not have such a con-
striction. Ants usually occur in small numbers; termites usually are more
numerous. Ants fly freely, do not lose their wings quickly, and may be
around for several days; termites are feeble fliers, shed their wings, and
disappear within an hour.
The brown, earth-like shelter tubes (Figure 2) built over part of the
foundation, or even on infested timbers, are visible evidence of infesta-
tion. If a shelter tube is in use, the inside is moist and there may be white
workers there. If a section is broken away, the workers will repair it. If
the tube has been abandoned, it will be dry and crumble easily.
Without the external evidence of winged termites or shelter tubes, it
is difficult to determine whether or not termites are present in a building.
Examination of posts or other wood in the ground near the building is
possible. This can be done by punching the wood near the ground line
with a screwdriver. If there is much of an infestation, the probe will open
up some of the burrows. These are very characteristic (Figure 4). The
soft portions of the wood are eaten, leaving the hard sections. There may
be accumulations of a sort of wood paste which resembles commercial
wood putty. There are also distinct spots of excrement.
A similar sort of examination can be made of wooden posts in the
basement, and of the sill and joists adjoining masonry porches.
Other insects also damage wood in houses. Carpenter ants excavate
wood softened by moisture or by rot to make a nest. They cast away
the bits of wood removed as a sort of sawdust, which accumulates in
Connecticut Experiment Station
Figure 4. Lower photo shows external appearance of infested wood;
top, a section of the same block opened to show termite burrows.
little piles below the infested wood. Ant burrows have no wood paste
present and no spots of excrement. They usually contain legs and other
hard portions of the insects which they use as food. Powder post beetles
eat the wood and leave pelleted deposits of excrement resembling wood
flour in the burrows. When they emerge from infested wood they do so
through small round holes eaten through the surfaces. The powdered
excrement sifts from these holes.
The old house borer (Hylotrupes bajulus L.) is very destructive in
houses in northern Europe. The common name is somewhat confusing,
because in Connecticut it has been found in new houses. The adult is
a long-horned beetle, emerging late in the summer and laying eggs in
cracks in lumber. The larvae feed for several years before maturing.
The beetles which emerge into a house probably cannot lay eggs in
finished woodwork. However, those which come out inside walls can
find suitable sites for egg-laying. In some cases in Connecticut, the
infested houses had been built only a year or two before the beetles
were found. It is likely that infested lumber was used in construction of
The wharf borer (Nacerdes melanura L.) is another long-honied beetle
occasionally found in buildings. It is usually found only in wood that
is wet for long periods of time. Since such wood will also rot, this pest
is not considered serious.
Termites in Buildings
Fungi also grow in wood, especially in damp situations. This causes
the "dry-rot" so often found in buildings. Actually fungi cannot grow
in dry conditions. Rotted wood may be checked on the surface, but
unless it is also infested by insects, there are no burrows.
PREVENTION OF TERMITE DAMAGE
The easiest way to avoid damage by termites is to take preventive
measures when the building is constructed. Special care is needed in
design and construction near or below grade level, so that termites do
not have an easy and convenient way to reach wood.
The most common means of entry in Connecticut has been through
masonry porches and terraces. The simplest construction to avoid this
entry is use of an additional thickness of foundation which prevents
contact between wood and fill (Figure 5).
Figure 5. Cross-section of construction of masonry porch or terrace show-
ing (1) easy access from fill (at left), and (2) construction with an extra
thickness of foundation (at right).
The other very common means of entry has been into wood extending
through the concrete basement flocr. This can be avoided by constructing
the floor first, and placing all wooden construction on it.
In houses built on concrete slabs, reinforcement is required to prevent
cracks, and there should be no joints underneath wooden partitions.
Especially tight construction of floors and walls is required if the
basement is to be finished with wood.
Care must be taken to avoid changes that allow termites to enter
after a house is built. Wooden posts or trellises set in the ground and
attached to the house furnish easy access to termites. Additional fill to
raise the grade may bring the soil in contact with wooden construction.
Termite-resistant construction should be considered seriously for houses
Connecticut Experiment Station
which will be supplied by water from a well on the premises. Details for
such construction can be found in USDA Home and Garden Bulletin
Some termite control companies have developed systems of pretreating
the soil under and around houses during construction. This allows thor-
ough treatment in areas which are hard to reach after the building is
completed. It is an excellent supplement to other precautions, especially
when there is to be extensive wooden construction in basements, or a
building on a concrete slab. The method must be used with care if the
water supply of the building is from a well on the premises (see also
Susceptible materials, such as books, paper, clothing, and leather
goods, stored in infested buildings may be damaged by termites. Such
materials may be protected by storage on free-standing shelves, pref-
erably metal, or even on wooden shelving constructed on short masonry
piers (Figure 6).
Figure 6. Records stored on a termite-proof rack
in the basement of an infested building.
Control of Termites in Buildings
Serious damage to the structure of infested buildings is more a matter
of years than of weeks or months. For this reason, the decision as to how
and when control measures need be taken can usually be reached de-
liberately. Even if there is evidence of structural weakness (as in older
buildings) temporary support can be provided while plans are being
made for repairs and control.
Changes in the structure of an infested building to conform to termite-
Termites in Buildings 13
resistant specifications have usually prevented further damage. However,
such changes may be relatively expensive, and many people have pre-
ferred the less expensive chemical treatment of the soil around and under
the building. The principle on which these chemicals work is the thor-
ough mixing of an insecticide toxic to termites in the soil occupied by
termites, or through which they must travel to reach the building.
Individual termites are very susceptible to many insecticides. The
problem always has been to apply the material in the right places. Sev-
eral highly effective soil insecticides which persist for years are available.
When these are applied properly to the 6 inches of soil adjoining the
foundation, and under slabs, control has resulted.
These insecticides are usually applied in trenches dug on the outside
of foundations, and through holes drilled in the floor of masonry porches
or terraces and through basement floors (both adjoining the foundation
and along any infested partitions).
Houses on Concrete Slabs
The trench may be about 6 inches wide and not more than a foot
deep. The diluted insecticide is applied at the rate of 1 gallon for 5
linear feet of trench. The soil is replaced in the trench, and sprinkled
with about 1 gallon for each 10 linear feet. For masonry porches, the
same amount of material is poured through a series of holes about a foot
apart and 6 inches outside the main slab. If termites are coming up
through expansion joints or cracks in the slab, a similar amount of ma-
terial is applied through holes drilled along the line of the joint or crack.
Houses with a Basement
The trenches may be 6 or 8 inches wide and at least a foot deep. A
bar is used to make a series of holes about a foot apart and at least 2
feet deep in the bottom of the trench. Treating solution is applied at
the rate of 2 gallons for each linear foot of trench, the trench filled
and sprinkled with about 1 gallon for each 10 linear feet. If the foun-
dation has voids, holes can be made in the masonry joints, and at least
1 gallon of treating material used for each 5 linear feet of wall. Masonry
porches, and if necessary basement floors, are treated as for slab houses.
Soil insecticides are usually applied as water emulsions. The concen-
trated insecticide is mixed with water to form the desired concentration.
The ones used most commonly in Connecticut have been chlordane,
dieldrin, and heptachlor.
Chlordane has been used at 1 percent dilution, which means 1 gallon
of 46 percent concentrate in 48 gallons of water.
Dieldrin has been used at .5 percent dilution, or 1 gallon of 1.5-lb.
dieldrin concentrate in 36 gallons of water.
Heptachlor was also used at .5 percent, or 1 gallon of 23 percent
heptachlor concentrate in 48 gallons of water.
These insecticides are somewhat toxic to people, and the concentrates
should be handled only when wearing rubberized gloves. There are other
directions for safe use on the labels.
14 Connecticut Experiment Station Bulletin 695
The Federal Housing Administration has issued standards for Indi-
vidual Water Supply Systems (wells). These standards provide (1102-3.3)
that the minimum distance between a well and chemically poisoned soil
be 100 feet. This distance may be reduced to 50 feet "only where the
ground surface is effectively separated from the water bearing formation
by an extensive, continuous impervious strata of clay, hardpan, rock, etc.
The well shall be constructed so as to prevent the entrance of surface
water and sewage as effectively as the undisturbed impervious soil prior
to the well construction."
"1102-3.5 Individual water supply systems are not acceptable in areas
where chemical soil poisoning is practiced if the overburden between
the ground surface and the water bearing formation is coarse-grained
sand, gravel or creviced or channeled rock which will permit the re-
charge water to carry the toxicants into the zone of saturation."
Commercial Termite Control Companies
There are companies in Connecticut that specialize in termite control,
and many pest control operators (sometimes called exterminators) make
termite control treatments. All are licensed under state statutes, and
have passed an examination on safe use of pesticides.
In general, termite treatments are in the same category as other items
of maintenance of buildings; a competent professional with proper
equipment and a knowledge of the subject can do a better job than an
inexperienced home owner. Selection of an operator may be made on
the same basis as any other type of building maintenance.
AGRICULTURAL EXPERIMENT STATION
NEW HAVEN, CONNECTICUT 0650*
1/ [Vector V
U. S. DEPARTMENT OF AGRICULTURE
Permit No. 1136
WILBER CROSS LIBRARY
UNIVERSITY OF CONN .
STORRS, CONN . 06268
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