NOT TO BE TAKEN FROM THE LIBRARY

FORM 3427 5M 12-39

SAN FRANCISCO PUBLIC LIBRARY

3 1223 90030

7357

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CITY AND COUNTY OF SAN FRANCISCO .

DEPARTMENT OF PUBLIC WORKS
PROJECT NO. 2-F2-342

San Francisco — May 1936

REPORT

of the

SAN FRANCISCO TERMITE SURVEY

By

A. A. BROWN, Consulting Engineer

A publication destroyed by subterranean termites. Altacl/ed on
shelves of the Academy of Sciences, Golden Gate Pari/.

511366

FOREWORD

Termites in San Francisco, as reported to the Department of Public
Works by property owners, are apparently infesting homes in every district
of the city. Judged by these reports, the damage to houses has been increas-
ing in recent years due, seemingly, to the rapid building up of the city and
the consequent multiplication of buildings and structures designed and con-
structed without regard to this menace. In order to ascertain the extent of
the damage to property and to study the incidence of termite infestation in
relation to any peculiar conditions which might be favorable to their increase
and dissemination, the San Francisco Termite Survey was inaugurated by
the City of San Francisco in cooperation with the Federal Emergency Relief
Administration and the State Emergency Relief Administration. This survey
provided an opportunity for the study of the effect of changed physical con-
ditions in relation to this important problem. Technically trained men were
assigned to this work from the relief rolls and given a course of training of
about three months prior to their making field inspections. ,

Because of his extensive experience and knowledge of the termite
problem, the City of San Francisco employed A. A. Brown, a consulting
engineer who had been chairman of the Termite Investigations Committee,
to direct the survey. His report of this survey is presented herewith in non-
technical form for the benefit of lay readers and property owners.

ALFRED J. CLEARY,

Chief Administrative Officer of the
City and County of San Francisco.

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CITY AND COUNTY OF SAN FRANCISCO

REPORT
OF THE

SAN FRANCISCO TERMITE SURVEY
Project No. 2-F2-342

BY

A. A. BROWN, Consulting Engineer

CONTENTS Page

Foreword 1

Introduction 3

Termites Native to California 3

Factors Contributing to the Distribution of Termites in San Francisco.... 4

Characteristics of Types Found in San Francisco 9

Beetles 15

Fungi 20

Building Details which Contribute to Termite Infestation 2 1

Difficulties Encountered in Control Measures 23

Scientific Findings of Biologists 28

Altered Physical Conditions Favor Termite Infestation 29

Suggestions to Home Owners 31

Summary 37

Recommendations 38

Acknowledgments 39

Appendix 41-46

SAN FRANCISCO TERMITE SURVEY

3

INTRODUCTION

The termite menace in the United States, until recently only vaguely
appreciated, is as serious and widespread as it is inevitable. With more than
fifty species of the insect native to the country, they are found in destructive
and ever-increasing numbers in the forty-eight states of the Union. From
their original useful function as forest scavengers, breaking down and
restoring wood tissue to the soil and air, termites have become a significant
economic problem as a result of the artificial accumulation and widespread
distribution of their food supply in the form of timber in man-made structures.
The result has been to facilitate the spread and the rapid increase in number
of these insects. To date there have been no adequate control measures be-
cause the habits and activities of termites have been so little understood by
the construction industry and the general public.

TERMITES NATIVE TO CALIFORNIA

The first impression to be corrected is the common idea that the observ-
ance of termite work for the first time in a neighborhood indicates an invasion.
Professor S. F. Light, of the University of California, says :

"It cannot be too strongly emphasized that all the termites doing exten-
sive damage in the United States, and, indeed, all except one, or possibly two,
of the fifty-five species known to occur in the United States, are native species.
We are not facing, therefore, any sudden invasion of new forms, as many
have imagined, but simply an adjustment with species present for millions of
years before man entered upon the scene."

There are nineteen species of termites native to California.* The three
main habit groups into which the various species have been classified to be
found in San Francisco are : ( 1 ) damp-wood termites (scientifically known
as Zootermopsis anguslicollis Hagen) ; (2) dry-wood termites (Kalotermes
minor Hagen) ; and (3) subterranean termites (Rettculitermes hesperus
Banks) .

In nature, termites and their associated organisms have been the im-
memorial scavengers of forests, cleaning up the down timber and stumps, and
returning such wood to the soil and atmosphere. With the settlement of our
country, the land was subdivided and the boundaries usually marked by
fences. Roads were built, paralleled on each side by fences. These road-
ways were used as rights-of-way for the erection of pole lines, and the poles,
being placed in direct contact with the ground, provided a ready means for
these insects to move from their natural habitat in forests to man-made struc-
tures in towns and cities.

Associated with termites in this biological scheme of breaking down
wood fiber and returning it to the soil and atmosphere are the fungi (rot)
which grow in wood. Conditions favorable for termites are also favorable
for fungi. Fungus is a necessary element in the diet of termites. It is to them
the equivalent of our beefsteak, and without it, their diet would be com-

*Report of the Termite Investigations Committee, Termites and Termite Control, Uni-
versity of California Press, 1934.

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CITY AND COUNTY OF SAN FRANCISCO

parable to our living entirely on starches. The wood made available to ter-
mites in man-made structures differs from their food supply in nature, as the
tree from which lumber is cut is felled in the full flush of its activity when it
is rich in food values, whereas in nature termites live on dead and decaying
trees and stumps. In man's relation to their principal food supply, therefore,
he has created a huge reservoir of food in the man-made structures of our
cities which is far more desirable to termites than that which they find in
nature. He has also provided them with shelter and warmth in our furnace-
heated homes. All these factors are designed to stimulate their activity ; and
since they multiply by geometrical progression, it is to be expected that they
will move in and occupy the available food supply. This is precisely what
they are doing.

FACTORS CONTRIBUTING TO THE DISTRIBUTION OF
TERMITES IN SAN FRANCISCO

Numerous factors contribute to the widespread infestation of buildings
within the city limits of San Francisco. Approximately 81 per cent of all
wood frame structures inspected were infested by one or more species of
wood-destroying insects ; 33 per cent of the Class C buildings were similarly
infested, as were also 36 per cent of the Class A, and 37 per cent of the Class
buildings.

Termites in San Francisco are not confined to any particular area or
district but are found throughout the city. The presence of dune sand has
no doubt been a contributing factor to the high percentage of subterranean
termites in certain districts, while our climate and proximity to the sea appear
to have stimulated the spread of damp-wood termites. Higher elevations such
as the Western Addition, and regions along the Bay shore such as Sea Cliff
and the Presidio, show a higher percentage of infestation by damp-wood
termites, while areas such as the Sunset, Richmond and Mission Districts
show a predominance of subterranean termites.

In analyzing the distribution of these insects within the city limits it is
well to resolve the problem into its constant and variable factors. In this
analysis certain elements may be considered constant as they are always true,
namely :

1. Food: Cellulose is the principal source of food for termites. Any
material containing cellulose, therefore, such as wood, paper, clothing, wool,
leather, and artificial materials containing a combination of these products,
is subject to attack by these insects.

2. Protozoa: Protozoa are always found in the gut of termites. They
are microscopic one-cell animals which make cellulose available to termites
as food. This fact is an important element in certain methods of prevention
and eradication since any substance which will destroy these organisms, will
ultimately kill the termite.

3. Fungi: Fungi are always associated with termites. They provide
the nitrogenous part of their diet which is necessary for their successful growth
and developlment.

SAN FRANCISCO TERMITE SURVEY

5

4. Wood-dwelling termites always make their home in wood. They
are divided into two major groups, one commonly known as the dry-wood
termite, and the other, the damp-wood termite. Both of these types leave
characteristic seed-like fecal deposits, commonly referred to as pellets, which
are distinctive in appearance and reveal the presence of the insects.

5. Ground-dwelling termites (commonly called subterranean termites),
make their home in part in the ground, and always maintain a connection
with a permanent moisture supply, which is usually found in the soil. These
termites do not leave seed-like pellets, but their burrows contain distinctive
marks from their liquid feces, together with a peculiar "frass" composed of
earth and partly-digested wood, both of which aid in disclosing their presence
in a structure. They frequently build covered runways over wood, brick,
concrete, or metal surfaces to reach a food supply not in ground contact.
These runways, which are made of earth and partly-digested wood and
lead from the earth to wood or vice versa, are characteristic of the ground-
dwelling termites.

In solving any problem, the difficulties are not in meeting situations
presented by factors that are constant, but by those that vary. Therefore,
as an aid to providing an adequate solution it is advisable to determine the
limits within which these variables operate. Among these variables are :

1. Moisture: Subterranean termites are dependent upon a constant
supply of moisture from some source. This is usually found in the soil. It is
possible, however, for them to colonize without ground connection if they
have other means of obtaining moisture. For example, an ocean liner at the
dock in San Francisco was found to be infested by an oriental subterranean
termite. In this instance they had colonized in the woodwork of a cabin
and were obtaining their moisture supply from a leaky coffee urn.

Dry-wood termites are able to colonize in dry, seasoned wood which
contains no free moisture. Any wood exposed to the atmosphere contains
some moisture which it absorbs from the air. The only wood that can be
considered free of moisture is that which has been oven-dried, and in a short
time even this oven-dried wood will absorb moisture if exposed to air. Wood
in which dry-wood termites were found contained 12.75 per cent of moisture
by oven-dry weight. This latter percentage of moisture is commonly present
in any wood exposed to air.

Damp-wood termites have an exceedingly wide range of tolerance to
moisture once the colony is established. However, some free moisture appears
necessary for the colonizing pair. These termites were found in wood con-
taining as much as 220 per cent moisture (waterlogged) , and also in wood
containing as little as 13.35 percent moisture by dry weight.

2. Temperature: Termites are normally attracted to warm places.
They thrive best in the tropics. Thirty years ago furnaces were not standard
equipment in basements of flats and residences in San Francisco, while today
the reverse is true. In fireproof concrete structures, subterranean termites are
often found entering the furnace room, no doubt stimulated to activity by
the presence of heat. A warm temperature, therefore, is a favorable con-
tributing factor to termite activity, although the degree of temperature will
vary greatly within structures.

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CITY AND COUNTY OF SAN FRANCISCO

3. Distribution of types: While there are three major habit types of
termites found in San Francisco, it does not follow that all three may be
grouped within the same structure. The distribution of these types (the two
major wood-dwelling and the subterranean termites) , is influenced by other
variable factors.

4. Soil Conditions : Soil would appear to be an important contributing
factor to the distribution of subterranean termites. Subsoils of San Francisco
consist of clay and sand, and a mixture of the two, overlying the bedrock
series of Franciscan sandstone, shale and serpentine. In certain of the lower
areas there is made-ground and swamp materials. The possible moisture
content of the soil depends upon the size and shape of the grains and the
degree of sorting. The great number of particles in clay, for example, and
their small size and shape, give it a high degree of hygroscopic content — that

(Fig. 2). Photograph of space between a wood frame building and a concrete structure,
where the wood forms used in constructing the concrete building were left in
ground contact. Subterranean termites heavily infested the wood forms and
also the wood frame building.

SAN FRANCISCO TERMITE SURVEY

7

is, moisture in the form of a thin film about each particle, which is not available
as free moisture. Sand, on the other hand, due to the larger size of its grains,
contains much more free capillary moisture. Clay may have a higher per-
centage of total moisture-content than dune sand, but the water in the former
is principally locked in and not available, while the water in sand is free
and available to termites. The capillary action of dune sand normally main-
tains free moisture relatively near the ground surface, presenting a condition
most favorable for the colonizing of subterranean termites.

5. Climate: The climate in San Francisco appears to be an important
element which contributes to the widespread distribution of damp-wood ter-
mites. These termites are found emerging on their nuptial flight beginning in
August and extending sporadically through the fall and winter months. The

(FlG. 3). Photograph of a 10" x 10" raw wood column taken from the basement of a
6-stor\f apartment house. The column, supported bp stilts to show its length
before the subterranean termites discovered it, was originally encased in metal
lath and plaster. Processed lumber should be used under such conditions, and a
steel plate extending beyond the plaster line should be placed under the column.

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CITY AND COUNTY OF SAN FRANCISCO

(FlG. 4). Photograph of ends of raw timber joists taken from a Class C building de-
molished to provide space for approaches to the San Francisco-Oakland Bay
Bridge. These joists were 4 feet above the ground, the ends resting in a con-
crete wall. Note damage to ends of joists by subterranean termites. The ends
of such joists should be processed with non-water-soluble chemicals to render them
immune to fungi or termite attack.

early rains of the fall, beginning in September or early October, extend in-
termittently until about the first of June. June and early July are dry months,
followed by fogs heavily laden with moisture during the latter part of July
and August, when there is another brief period of fair weather before the
early fall rains begin. This climatic condition is favorable for the colonizing
of damp-wood termites, since they seem able to avail themselves of moisture
in the air in addition to obtaining moisture by body processes from otherwise
dry wood.

6. Natural rvood preservative: It has been commonly observed that
certain pieces of wood will resist the forces of decay longer than other pieces.
This unequal resistance is due to the variance in distribution of nature's
preservative in the tree from which the wood was taken, and probably
accounts for the fact that termites select those pieces of wood that are less
durable and where they can more readily grow fungi as an element for
their diet.

7. Construction: Certain building practices commonly in use by the
construction industry under existing ordinances provide ideal opportunities
for infestation by one or more of the species of termites found within the city
limits (figs. 2, 3, 4).

SAN FRANCISCO TERMITE SURVEY

9

The above variable factors enter into the distribution of these two
major habit types of termites, and, while specifically applicable to the City
and County of San Francisco, are of broader significance and can be applied,
with variations, to other communities. Hence it is reasonable to conclude
that climatic and soil conditions, together with faulty methods of construc-
tion, are the three major variable factors influencing the distribution within
the city limits of the two most important species of termites.

CHARACTERISTICS OF TYPES FOUND IN
SAN FRANCISCO

Dry-Wood termites: In this survey, dry-wood termites were found
only in the region of Golden Gate Park, adjoining: the Richmond District.
These insects, if permitted to extend the boundaries of their present in-
festations, have great potential possibilities for doing damage. As their
name implies, they live in the dry, sound wood of trees, poles, posts, and
buildings. They rarely if ever enter the ground, and require no special
moisture supply. These termites were found swarming in the middle of
the day in bright sunshine, during the latter part of July. Their normal
time to swarm is from eleven o'clock in the morning to three o'clock in the
afternoon, the peak of their swarm occurring at the noon hour. The
alates are brown, with lighter shaded wings, and slightly less than five-

(FlG. 5). Photograph of a group of individuals from a colony of the damp-rvood termite,
ZoOTERMOPSIS ANGUSTICOLLIS, natural size. Note the numerous nymphs, one
soldier, and five winged reproductives, or alates, ready for srvarming.

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CITY AND COUNTY OF SAN FRANCISCO

eighths of an inch in length from end to end including the wings. During
their flight, they mate and seek new homes, entering cracks, nail holes or
joints, or where these are not available, they dig into the solid wood.

The most common method of controlling these insects is by blowing
poison dust into their runways. The poison adheres to the fine sensory hairs
on their bodies, and, due to their constant habit of grooming, is spread rapidly

(FlG. 6), A 6" x6" post gutted by damp-wood termites and fungi. Note the sound
appearance of the exterior.

through the colony. Since these termites enter the wood directly at the
swarming period, it is necessary to stop the colonizing pair from entering by
protecting the wood. This can be done by the use of a toxic, penetrating,
priming coat of paint, or by spraying with a penetrating toxic preservative
that is not readily water-soluble.

Damp-Wood termites: The winged damp-wood termites are about the
same color as the dry-wood termites but are larger. From tip to tip alates
measure about an inch (fig. 5). They are usually found flying in the late
afternoon or early evening. They are commonly attracted to electric lights.
Beginning about the middle of August and extending through the fall and
winter months, these termites emerge at sporadic intervals on their nuptial
flight. The colonizing pair appear to require some free moisture, such as is
found in wood that has been dampened by rain, etc. Once established, how-
ever, they have a very wide range of tolerance to moisture, being found in
wood piling at low tide line in a building in the vicinity of the San Francisco
waterfront. Termites from this same building were placed in glass jars and

SAN FRANCISCO TERMITE SURVEY

11

(Fig. 7). Section of a raw timber building-column infested by damp-wood termites.
Spray treatments do not reach concealed colonies as shown in this photograph.
Experimental methods illustrated in figures 22 and 23 can be satisfactorily adopted
for eradication of termites under the conditions shown.

provided with a quantity of dry wood and a small amount of moist paper as
an aid to their establishing a colony under new conditions. At the end of
six months the colony was still healthy, and specimens of the wood then
tested contained 1 6.08 per cent moisture by dry weight. These termites have
been referred to as rotten-wood termites but are generally called damp-wood
termites (fig. 6). Both of these terms, however, are subject to some restriction
in use. The name "rotten-wood termite" implies that one would expect to
find them in rotten wood. This is not necessarily true (fig. 7). As previously
mentioned, fungi are always associated with termites, and since these insects
live in damp wood and carry fungi with them, it naturally follows that they
are frequently found in decaying wood ; but this, it appears, is only the case
where they are able to control the growth of fungi. Where conditions favor
an excessive growth of fungi, it has been found that termites move to other
parts of the structure where they can control its growth and development
(see fig. 21). We found many instances where damp-wood termites had
been present but appeared to have died out due to the excessive amount of
decay that had taken place in the wood. On more careful examination,
however, the investigator found that these termites had not died, but had
abandoned the decayed wood and moved to sound wood where conditions
were more favorable to their mode of living and where the growth of fungi
could be controlled. These observations probably explain both the failure
of workmen to locate such termite colonies, and the finding of termites in
structures immediately following the completion of attempts at eradication

12 CITY AND COUNTY OF SAN FRANCISCO

(fig. 8). Among the buildings inspected were a considerable number that
had been repaired during the year 1935. Inspections were made in some
instances within twenty-four hours after completion of the repairs, and in 77
per cent of these buildings termites were still present. The damp-wood

(FlG. 8). Photograph of concealed damage by damp-Tvood termites in building illustrated
in figure 9. The building appeared sound prior to removal of the exterior sheathing.

termites are very destructive to property in San Francisco, being present in
approximately 50 per cent of the structures inspected and found to be in-
fested. While infestations by these termites are not quite as numerous as
those of the subterranean variety, their damage to buildings, per infestation,
is far greater. The cost of making repairs on a job where these termites are
involved is usually much more expensive than in the case of ground-dwelling
termites as they often extend their activity from the foundation to roof-
rafters (fig. 9). In one instance they were found on the fifth-floor level of a
fireproof structure (fig. 10).

Subterranean Termites: The winged subterranean termites are
almost jet black with light gray wings, the wings being about twice
as long as the body (fig. 11). From tip to tip they measure about half
an inch in length. On the first sunny day following the first heavy rain in

SAN FRANCISCO TERMITE SURVEY

13

(Fig. 9). The building illustrated in this photograph was recently razed, thus providing
an opportunity for a thorough inspection of all parts of the structure. The degree of
infestation by damp-wood termites is indicated by shading. The damage rvas greatest
near the top, probably due to leaky roof and siding.

the fall, they emerge from the ground or from buildings in large numbers on
their mating flight. Sporadic flights continue through the fall months. A
minor flight occurs on bright, sunny days in the spring following a heavy
period of rainfall. It is this variety that is commonly mistaken for flying ants.
Since these termites nest in the ground at varying depths, the time required
for moisture to reach the colony and stimulate the mating flight will vary.
We found winged termites of this species in basements many feet below the
street level as late as June, indicating that the time required for moisture to
reach them was greatly delayed. After shedding their wings, they mate and
seek new homes either in the ground, or in wood in contact with the ground,
or in wood where free moisture is available. They frequently enter concrete
structures through cracks, joints, defects, wood-block spreaders (fig. 12)
that were embedded at the time the concrete was poured, or along pipes,

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CITY AND COUNTY OF SAN FRANCISCO

(Fig. 10}. A housewife called the survey office to report that she had found a lot of
seeds under a rug in her home. The photograph shows the seed-like fecal pellets left
bp the damp-wood termites which penetrated the flooring leaving a row of holes on
the surface. The termites had also damaged the rug along the line of holes. This
floor was approximately 10 feet above the ground.

conduits, etc., causing damage to stored material containing cellulose, or by
building their characteristic covered runways (fig. 1 3) to reach such material.
The most extreme case we found was where they had entered through joints
in a concrete floor 25 feet below the street level, and constructed their covered
runways to furnishings on the main floor above (fig. 14). Subterranean
termites not only build covered runways over concrete, brick, etc., but they
also erect coral-like structures (fig. 15) to reach wood not in contact with
the ground. They appear unable to create moisture from wood to the

SAN FRANCISCO TERMITE SURVEY

15

(FlG. 11). Photograph of subterranean termite winged reproduciives (alates) swarming
in the basement of a fireproof building, near the furnace room on July 2, 1935.
Termites gained entrance through a crack in the concrete floor.

extent that wood-dwelling termites do, and therefore are more dependent on
some exterior supply. These termites were present in approximately 67
per cent of the buildings inspected and found to be infested. (See fig. 1 6) .

In the initial attack of wood-dwelling termites on a structure, we are
dealing basically with the colonizing pair. Subterranean termites, however,
have their nests in the ground, possibly some distance from the point of in-
festation, and these nests may contain thousands of individuals. Their attack
therefore is made not by a pair of individuals, but literally by an army. They
build galleries under the surface of the ground to wood in ground contact, or
to wood placed away from ground contact, making it necessary in dealing
with them, to provide a depth of treatment sufficient to destroy a colony rather
than a pair of individuals.

BEETLES

Wood-boring beetles were found doing damage to structures and to
furniture in approximately 1 1 per cent of the buildings that were inspected
and found to be infested by wood-destroying insects (fig. 17). We found
these adult beetles flying during the months of June, July and August.
Mating takes place soon after emergence from the wood, and as the result
of their ability to fly considerable distances, the females are enabled to spread

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CITY AND COUNTY OF SAN FRANCISCO

their attack to uninfested wood in the vicinity. Normally they shun the light,
and are most active at dusk and during the night.

Late one evening I was called to the home of a man who explained
that a day or two earlier he had purchased a cord of oak firewood which was
stored in his furnace-room. Upon entering the furnace-room that same
evening, he found a quantity of small black bugs emerging from the wood.
Upon examining them, I found three different species of adult wood-boring
beetles on their nuptial flight. The floor, walls and ceiling were thickly
spotted with insects, and they had crawled under the door leading from the
furnace-room and were finding their way to the woodwork in the upper part
of the home. The firewood came originally from Sonoma County, and had
been purchased from one of the local wood yards. Prompt action in this case
probably prevented a home which had been built only a few months previous
from being thoroughly infested by these pests.

Wood paneling in another home, which had been free of infestation
for many years, was found during the summer of 1 935 to be infested with
beetles. In the basement of this home was stored a quantity of beetle-infested
oak firewood, some of which had been there for about three years. The same
species of beetle found in the firewood was found in the wood paneling.
These instances indicate the need for controlling the sale of infested wood.

(Fig. 12). Subterranean termites gained entrance to the basement of an 8 -story Class C
building through a raw wood-block spreader left in place at the time the concrete
wall was constructed. Termites constructed runways over the concrete to the raw
wood joists above. Winged reproductives were swarming on June 4, 1935.

SAN FRANCISCO TERMITE SURVEY

17

(FlG. 13). Covered runways made of earth and partly-digested wood constructed by
subterranean termites on a vertical concrete wall to reach the raw wood frame of the
building above.

Powder post beetles and1 death watch beetles are the types most fre-
quently found in San Francisco (fig. 18). The adults of these beetles are
small, being less than a quarter of an inch in length, and black in appearance.
Their larvae are grublike. Beetles live for generation after generation in old,
well-seasoned timber, honeycombing the wood and reducing it to a condition
of powder, which plugs the old burrows or is expelled from time to time
through small openings. The small shot-hole openings, and the powdered
remnants of their workings in wood usually found on floors or ledges, indicate
their presence and differentiate them from termite workings.

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CITY AND COUNTY OF SAN FRANCISCO

clinic

(FlG. 14). Oak partitions covered with frass and runways. These partitions had been
stored for only 3 months in the basement of a fireproof office building. Some of the
partitions were damaged beyond repair.

(Fig. 15). Coral-like towers and tubes made by subterranean termites to reach raw woot
in a building, not in ground contact. All the towers parallel a hot-air duct.

SAN FRANCISCO TERMITE SURVEY

19

(FlG. 16). Croup of individuals from a colon}) of subterranean termites, RETICULITERMES
HESPERUS, showing the appearance of workers when a colony is opened. Natural
size.

Fumigation: In a number of instances which came to our atten-
tion, attempts had been made to eradicate beetle infestation by fumigation.
Subsequent inspections made, however, showed that beetles were still in-
festing the wood. These observations confirm the report of Dr. Merle Randall,
chairman of the Chemical Sub-Committee of the Termite Investigations Com-
mittee, which says:

"Most of the commonly used gas, liquids, and solid fumigating materials
were tested and all were found toxic to termites. The great obstacle to the
success of fumigation is the difficulty of reaching all the termites with the
poisonous vapors. The vapors do not diffuse readily through the termite
galleries, hence the termites were able to escape the effects of the vapors even
during a fumigation period of reasonable length. The surviving fragments of
the original colonies which remain defeat the purpose of fumigation."

(FlG. 17). Typical work of a powder post beetle in a Douglas fir floor joist. Note the
small emergence holes.

20

CITY AND COUNTY OF SAN FRANCISCO

FUNGI

Sagging floors, cracked plaster, jammed doors, and windows that are
difficult to open and close, are common results of the failure of wood in build-
ings (fig. 1 9) . Much wood failure is attributed to dry rot. In many instances
the failure is actually due to termite attack, the fungus being introduced to

(a) (b)

(FlG. 18). (a) LYCTUS CAVICOLLIS (Lec.) the commonest true powder post beetle in
California, (b) Hadrobregmus GIBBICOLLIS (.Lec), the most destructive native
California death watch beetle. These beetles are about 3/16 of an inch in length,
natural size.

the wooden members by termites. Decay is caused by fungus, a plant growth
which grows on and in wood and destroys its substance as it develops. Gen-
erally speaking, conditions which favor termite infestation also are favorable
for the growth of fungi. The most important factor in eliminating their growth
is moisture. Dry wood will not decay. Wood is food for fungi, but it cannot
be used as food unless it contains at least 1 5 to 20 per cent moisture by dry
weight (fig. 20). Neither can fungi use wood that is submerged in water.
The spores of fungi are always floating in the air and some 33 different kinds
were found by Dr. Esther C. Hendee to inhabit the burrows of termites of
the Bay area.* Good drainage and adequate ventilation are essential in
any program of eliminating damage to structures by fungi. Leaky roofs,
walls, window frames, down spouts, plumbing fixtures, etc. (see appendix) ,
all provide conditions favorable for the rapid growth of these organisms, as
well as providing conditions favorable for infestation by termites.

The Association of Termites and Fungi, Chap. 9, Termites and Termite Control.

SAN FRANCISCO TERMITE SURVEY

21

BUILDING DETAILS WHICH CONTRIBUTE TO
TERMITE INFESTA TION

Among the species of raw wood commonly used in the construction of
buildings in San Francisco, none were found to be immune to termite attack.
It is important, therefore, that care be exercised in the construction and main-
tenance of any building in which raw wood or raw wood products are used.

Brick veneer buildings backed by wood framing are often found to be
infested by termites. Brick veneer is not always watertight, and moisture
reaches the wood backing behind the brick. Brick foundations are also a
common source of difficulty as they draw moisture from the soil to the wood,

(FlG. 19). Photograph of raw timber joists destroyed by fungi in a warehouse.

making it thoroughly damp although placed as much as two feet from the
ground. Where concrete or masonry walls are inadequately waterproofed,
moisture reaches the wood frame on the inside and provides conditions favor-
able for the colonizing of wood-dwelling termites and fungi (fig. 21).

Certain methods of construction permissible under the present building
ordinance preclude the possibility of any untreated wood giving a satisfactory
use-life. In all classes and types of building wood floors are commonly nailed
to sleepers overlying concrete which is in ground contact. As has been previ-
ously noted dune sand (which predominates in this city) draws moisture by
capillary action close to the surface and creates a condition of dampness in
this type of construction which is not only favorable to the development of

22

CITY AND COUNTY OF SAN FRANCISCO

(FlG. 20). Photograph of fungi growing on the rvood frame of a building. Due to the
presence of moisture and lack °f ventilation, the structure tvas seriously damaged by
fungi.

fungi but also is necessary to subterranean termites. Defects in the concrete
slab invariably provide a ready means of access for termites ; and this, com-
bined with conditions favorable to the development of fungi, results in a very
short life for wood floors constructed over concrete in ground contact.

In discussing the necessity of renewing a wood floor built as described
above, the manager of a building recently remarked that every four or five
years he had found it necessary to replace the floor in question, and now felt
that he had given wood a sufficient trial and was desirous of using a wood
substitute. In this particular case, however, the wood flooring never had a
chance. Instead of using wood that had been chemically treated to make it
unavailable for either termites or fungi, he had been providing them with a
new food supply every four or five years under the most favorable condi-
tions for their use. The ordinance permitting the use of any material con-
taining cellulose under such conditions should, in fairness to the lumber
industry, be revised in line with our present knowledge of the dangers in-
volved.

Small Building Lots: Over large areas of San Francisco buildings
have been constructed on 25 foot lots, with adjoining structures built to
within an inch of the property lines, thus making it impossible ever to get
at the outside walls except from inside the basement. The wind-blown
debris that accumulates in these small openings when dampened by rain
water running down the sides of the buildings, provides ideal nesting places
for termites. Of 67 closely-built wood frame buildings in one block, all
but five were infested.

SAN FRANCISCO TERMITE SURVEY

23

DIFFICULTIES ENCOUNTERED IN
CONTROL MEASURES

The Termite Investigations Committee reports having found sub-
terranean termites nesting in the ground and attacking wood 165 feet dis-
tant. The physical conditions prevailing in San Francisco — provided by
ideal soil in the nature of dune sand, and small building lots causing struc-
tures to be built in solid rows — together with the ability of these insects to
construct galleries under the ground for considerable distances, changes the
problem from one in which only the individual property owner is concerned,
to a community problem as well.

Property owners who are interested in eradicating termites from their
buildings but find their neighbors careless or not at all interested in the
subject, are presented with a difficult situation where infested buildings
abut their property. During the course of the survey this difficulty was
discussed by a number of property owners who desired to remove the

(FlG. 21). Raw wood supports for concrete or brick porches and steps are frequently
destroyed by termites and fungi. Such areas should be well ventilated, and wood
used for the purpose should be chemically processed.

24

CITY AND COUNTY OF SAN FRANCISCO

menace from the neighborhood, but, under existing laws, there was nothing
they could do about it. The problem presented, however, suggests the
necessity for studying remedial legislation so that it might be possible for a
majority of property owners in a neighborhood to institute a general pro-
gram of eradication. In San Francisco we are not dealing with a theo-
retical problem that termites might infest structures, but with the reality that
termites are widespread.

The hidden mode of life of all termites renders impracticable the con-
trol methods used for other insects, such as biological control by the use of
enemies, poison bait as in the control of the common house ant, fumigation,
spraying as in the control of orchard pests, or the poisoning of mosquito-
breeding grounds. They live shut off from the light in enclosed passage-
ways, either in the wood on which they feed, or partly within the wood and
partly within the earth.

Inspection: In existing structures a careful and intelligent inspection
by a person familiar with the building industry, and possessing a knowledge
of the life-habits of the various kinds of insects and organisms that do dam-
age to wood and its products, will prove of great aid in reducing the
likelihood of termite infestation. The old adage, "An ounce of prevention
is worth a pound of cure" is applicable to the termite situation. Inspections
frequently reveal conditions favorable for termite infestation which, if im-
mediately remedied, will avoid the necessity of future costly repairs. Ter-
mite damage is by no means confined to old buildings. Many of the older
structures were better built than new homes constructed by speculative
builders. During the boom days many homes were built with "Queen
Anne fronts and Mary Ann backs." Such buildings, in which emphasis was
placed upon appearance rather than upon substantial workmanship, are
now paying the penalty for many careless and slipshod construction de-
tails. Wood-destroying organisms in one such home less than two years old
caused such severe damage that an entire wall had to be replaced. As
previously mentioned, new, fragrant lumber is more attractive to termites
than old, dry, seasoned material. Consequently, any faulty condition in
recently constructed buildings which may be disclosed by proper inspection
should be promptly remedied.

A common means of locating the presence of wood-dwelling termites
is by their characteristic fecal pellets. From time to time openings are made
in the wood and these pellets discharged from the runways. The pellets of
the dry-wood termite are smaller than those of the damp-wood termite,
and have a characteristic shape and appearance. The pellets of the damp-
wood termites also have a characteristic form but appear to vary in size
owing to the presence of moisture. Where there is much moisture the pellets
are larger than when they have colonized in relatively dry wood. All
species of termites reveal their presence at the swarming time when the
winged members of the colony emerge to mate. This always affords the
alert property owner an opportunity to learn the extent, if any, of termite
infestation in his building. Subterranean termites reveal their presence at
the swarming period, and also by their characteristic covered runways,
coral-like towers, and frass. These termites seal the cracks, joints or defects

SAN FRANCISCO TERMITE SURVEY

25

in the wood with their frass as a means of controlling the circulation of air,
and in this way leave the tell-tale evidence of their presence.

References are found in current literature suggesting the necessity of
destroying the queen as a means of controlling termite infestation. There
are certain species of termites where the queen develops essentially into an
egg-laying factory and becomes immobile. The royal chamber in such cir-
cumstances is guarded by a large number of soldiers. In India, native
termite experts who have keen hearing are able to locate the position of
such queens by the characteristic noise made by the guarding soldiers. In
the case of the three major types of termites doing damage in San Francisco,
however, the royal pair are mobile and move from place to place, and
should they be destroyed, each colony contains supplementary reproductives
which in a period of from five to six weeks will produce a new king or
queen, the latter more fecund than the original. When dealing with wood-
dwelling termites in San Francisco, therefore, it is important that all mem-
bers of a colony be destroyed, as any survivors after the relatively short
period of a few weeks can re-establish themselves and continue their
destructive activity. Where the nest is in the ground, as is generally the
case with subterranean termites, the royal pair is rarely disturbed by the
methods used for eradication.

Misinformation given to the public: Many high-pressure sales or-
ganizations prey upon property owners due to their ignorance of this im-
portant subject. Materials under ambiguous names are now being offered
to home owners for the control and prevention of termites. We quote from
a recent circular mailed by the manufacturer of one of these products to
architects and engineers, in which the writer expressed impatience with
laboratory methods used by research scientists in determining the efficacy
of products offered for the purpose of termite control :

"For years architects, builders and home owners, in order to protect
their buildings, have been obliged to follow a stereotyped rule laid down by
some conscientious professor who never lived in a structure after his ideas
of the proper termite control medium had been applied . . . His natural
honesty of purpose, if backed with practical experience, would stop the use
of poisonous materials that leach out killing plant life, pets and endanger-
ing the lives of children when applied under and around the outside of the
house. However, his laboratory tests prove that this or that will kill ter-
mites, and it has been unfortunate for the real builders that laboratory and
not practical standards have been in vogue."

The material offered the public by this manufacturer depends largely
upon cyanide for the asphyxiation of termites. In the opinion of Professor
Frank T. Green, City Toxicologist, it constitutes a real menace to human
health. In the circular the manufacturer of that product is criticizing the
professor who objects to the use of materials which create a hazard to
human life in dealing with this problem in the home. He goes on to say :

"Has this theoretical practice of years stopped termites? No. They
are increasing in the proportion of each queen laying 86,400 eggs a day."

26

CITY AND COUNTY OF SAN FRANCISCO

We quote some of the misinformation contained in the circular of
another manufacturer:

"The queen lays an egg every two and one-half seconds, night and
day, for approximately ten years. Unlike humans, termites never rest. At

this rate the colony increases 24 a minute, 1440 an hour, 34,560 a day,
totaling 12,614,400 a year. In the spring and fall the alates take wings
and swarm to form new colonies. This gives you an idea of just why they
are so destructive."

Dr. A. L. Pickens, of the University of California, devoted his un-
divided attention for a number of years to the study of subterranean termites
for the Termite Investigations Committee. He reports:

"Some of the largest supplementary queens can lay 60 to 80 eggs a
day . . . Some of the African species it is estimated lay 4,000 eggs per
day ; and Dr. Emerson of the University of Chicago counted 7,000 eggs
laid in one day by a queen of one of the African species."

In the literature of one of these sales organizations they have the
queen producing 86,400 eggs in twenty-four hours, and in the other, 34,560
eggs in a day; whereas our scientists actually found that the subterranean

(FlG. 22). Portable equipment used for pressure-treating experimental building sections,
using a refined creosote colored T»ith an oil-soluble dye. Small holes 3/32 of an
inch in diameter were bored to within Yi inch of the opposite side, into which a
hollow screw was inserted, fitted with an Alemite connection. The holes were
spaced about 18 inches on centers. All concealed joints were thoroughly coated
with preservative. Pressures of from 200 to 250 pounds per square inch proved
most satisfactory in treating Douglas fir.

SAN FRANCISCO TERMITE SURVEY

27

(FlG. 23). Photograph of a 4" x4" Douglas fir 4 feet 6 inches long, into which pre-
servative was forced under pressure. Note the stain at the end showing that the
oil had passed entirely) through the post.

termites, with which we are dealing, may produce from 60 to 80 eggs a
day. Such misinformation often creates a feeling of hysteria in the public
mind against the use of wood and its products. If termites actually in-
creased in the fantastic proportions mentioned above, they would long since
have taken complete possession of our homes. It is advisable, therefore,
for property owners to deal with well-established, reputable business houses
when seeking advice and information for the control and eradication of
these pests.

The use of a spray has almost assumed the proportions of a panacea ;
yet it is utterly impossible by such a method of control to reach termites
deeply embedded in timbers (fig. 7). Methods adapted to the pressure-
impregnation of lumber in place are available (fig. 22), the preservative
being forced into the wood under pressures up to 300 or even as high as
500 pounds per square inch. In fig. 23 a preservative was forced through
a 4" x 4" piece of Douglas fir 54" long. A small hole 3/ 32nds of an inch
in diameter is drilled across the grain to within about Yl inch of the
opposite side, and a hollow screw fitted with an Alemite connection in-
serted. The preservative is then forced through the wood, directly entering
any existing termite runways and destroying members of the colony. There
is no panacea for the eradication of termite-infested homes, as conditions
vary greatly both in structures and methods of attack by termites.

28

CITY AND COUNTY OF SAN FRANCISCO

SCIENTIFIC FINDINGS OF BIOLOGISTS

Men of pure science are frequently criticized for the apparently im-
practical studies undertaken in their laboratories. The biological researches
into the life and habits of termites made by these men, extending over many
years, is now the groundwork upon which it is possible for architects,
engineers and contractors to approach the problem with sufficient basic
data to find a reasonable practical solution.

Among the many phases of research undertaken in the laboratory of
Professor Charles A. Kofoid of the University of California was one deal-
ing with the normal sexual development of the supplementary reproductives
inhabiting termite colonies. It was found first that termites constantly groom
themselves and each other, a custom which extends to the royal pair. Then,
by experimenting, they found that the royal pair gave off a substance from
their bodies which, upon being distributed through the colony by grooming,
inhibited normal sexual development in the reproductive so long as that sub-
stance was available. This scientific fact standing alone meant little, but
when interpreted in the light of experience in field observation, it explained
the presence of secondary kings and queens in colonies which were appar-
ently branches of an original colony that had become separated from the
other members. Further application of this important basic fact disclosed
the necessity when dealing with wood-dwelling termites of entirely destroy-
ing the colony and not merely the reproductive pair, since potential kings and
queens are always available to replace the original royal pair.

It is a well-known fact that arsenic is a deadly poison to all forms of
animal life including wood-destroying insects. Research studies made by
Doctors Charles A. Kofoid, R. Stohler and Esther C. Hendee * in the
biological laboratories of the University of California disclosed the interest-
ing fact that certain fungi commonly found in soils of the Bay region and
in termite colonies use arsenic in their metabolism and release an arsine gas.
Arsenic has been commonly used by exterminators for ground treatment to
prevent soil-dwelling termites from gaining access to a structure from their
nest in the ground. Thus we find with these two organisms so closely asso-
ciated, that what is poison to one becomes an aid in body processes to the
other; again indicating the necessity for understanding the vast mass of
scientific data now available before attempting the application of remedies.
Too much cannot be said in praise of these men who have contributed years
to the study of minute phases of termite life that are now proving of in-
estimable value when properly interpreted and applied to the problem of
termite prevention and control. Such men often spend a lifetime studying
one small phase of a problem apparently of little practical value but, when
fitted into the entire picture, helps to make the whole possible, as one piece
of tile does its bit to complete a beautiful mosaic. Such scientific facts are
the products of many laboratories and the work of scientists in widely
separated places. The limited space available in this report does not permit
the listing of the many scientific facts recorded, instanced by those mentioned

*The Association of Termites with Arsirte-producing Fungi, Termites and Termite
Control.

SAN FRANCISCO TERMITE SURVEY

29

above, nor the correlation of one to the other, and their application to the
practical phases of the problem of termite control. Suffice it to say that
biologists have made available sufficient data for those in the field of applied
science to successfully inaugurate a program of control. This is another
instance of the ever-widening influence of the biologist.

ALTERED PHYSICAL CONDITIONS FAVOR
TERMITE INFESTATION

It is an established scientific fact that wood which remains submerged
in water has an indefinite life. Recognizing this fact, engineers endeavor
to so cut the tops of wood piling, which provides support for many build-
ings in our city, that all the wood in the piling will be submerged at all
times. The coming of automatic sewage ejectors, the need for garage space
in basements, and many other changes in our mode of living have made
necessary the use of more space below the ground in commercial structures.
A few years ago, rain falling upon roofs was permitted to run to the streets
and the soil. Following the earthquake and fire of 1906, the building
ordinances were revised making it mandatory that all conductors of such
waste water be connected with the sewer. The old cobblestone pave-
ment which formerly lined our streets permitted rain water to reach
the soil and replenish the underground supply. The hard asphalt
surface now in use has completely altered that situation; so that
today the combined effect of the physical change in the streets, the

(FlG. 24). Damp-wood termites were found infesting waterlogged wood piling at low
tide. Subsiding ground waters expose wood piling to the ravages of these pests.

30

CITY AND COUNTY OF SAN FRANCISCO

(FlG. 25). Underpinning of an apartment house destroyed by subterranean termites.
The top of the concrete foundation "was approximately at ground level inside the
basement. The entire area was littered with old lumber in ground contact, most
of which was infested by termites.

change in the building code, and the removal of ground waters to provide
dry basements, have resulted in the lowering of the normal water table and
exposing, in many instances, wood piling to the ravages of these pests
(fig. 24).

San Francisco has experienced severe earthquakes in the past, and
will probably experience others in the future. In such periods of testing,
wood frame structures have demonstrated their ability to withstand the
unusual strains put upon them. Termites in many instances center their
attack near the foundation of buildings, often at very vital places, neces-
sitating changes in the now accepted methods of wood frame construction
if wood is to retain its present favored position. Says Dr. Charles A.
Kof oid :

"There is no possibility of eradicating termites; they have existed for
millions "of years and will continue to exist despite anything man can do
about it. But their major damage can be controlled."

He adds:

"Wood is the material best suited for homes in an earthquake country.
It is economical to use. It is esthetically enjoyable. We love the feel of it.
We enjoy its pattern and colors. It lends itself to the hand of the crafts-
man and to the human need of change. It can be safely used in the face of
the termite menace. In a well-built city controlled by a proper building
code, termite danger will be reduced, the spread of infestation will be
checked, home investments conserved, and the earthquake hazard reduced."

SAN FRANCISCO TERMITE SURVEY

31

SUGGESTIONS TO HOME OWNERS

1. Check the masonry or concrete foundations of your home, both
inside and outside, to determine whether the top of the foundation at all
points is above the ground line. It is desirable to have a minimum clearance
of 6 inches. If you find the ground line at any point extending above the
top of the foundation, inside or outside, it is advisable to consult some one
familiar with the problem involved. It is often possible to avoid costly
future repairs by taking immediate action (fig. 25).

2. Where homes have been constructed with no wood in contact with
the ground but where, due to landscape gardening, the contour of the
ground line has been raised at one or more points above the top of the con-
crete foundation, such change creates an unnecessary danger to the build-
ing and often contributes to termite infestation. Carefully survey your
garden next to the house for such a condition.

3. While the city ordinance requires that all ground surface under
the house be ratproofed with a thin coating of concrete, many instances
were revealed by the Termite Survey where this work had not been done.
On inclined lots where ratproofing has been omitted, the sandy top soil is
often disturbed by individuals crawling or walking over it, causing it to
slide down hill and lodge against the interior partitions or the outside wall
on the low side, creating favorable conditions for termite infestation. Care-
fully inspect the interior piers, partitions and walls, particularly on the up

(Fig. 26). Wood forms around concrete footing left in ground contact provided sub-
terranean termites easy access to main floor above. The rarv-timber girder, joists
and flooring had to be replaced. Note the typical frass and hanging tubes.

32

CITY AND COUNTY OF SAN FRANCISCO

side of sloping ground, and make sure that the earth is not in direct contact
with the wood frame of the building. In exposed positions, wind-blown
sand is often found banked against the side of a wood frame building that
had been constructed with ground clearance.

4. Do not leave stumps and roots of trees under your building.
Neither should wood and rubbish be permitted to accumulate on the ground
as they provide breeding places for termites. Good housekeeping in the
basement of your building will prove to be a distinct aid in discouraging
termites from entering your home. Any wood in ground contact attracts
termites.

5. Wooden forms used in the construction of concrete piers and con-
crete foundations often provide termites with a ready means for entering
the underpinning of your home (see fig. 26). In many instances wood
forms have been left in place and embedded in ratproofing, these forms
extending to ground contact. Carefully inspect all concrete walls or piers,
both inside and outside, and if such wood forms are found they should be
promptly removed.

6. Do not permit the wood framing around meter boxes or basement
ventilators to come in contact with the ground.

7. If water enters your basement during the rainy season, every effort
should be made to correct faulty drainage. Such damp conditions encour-
age infestation by termites and damage by fungi. Frequently the cause of
moisture in basements can be traced to roof drains discharging against the
house, or to refrigerator drains being permitted to empty onto the ground
beneath the building. Every effort should be made to maintain the ground
in basements free from moisture.

8. Good ventilation is a distinct aid in maintaining dry basements.
Do not permit shrubbery in the garden to interfere with the free circulation
of air through basement ventilators. A musty odor in the basement is a
good indicator that all is not well with your home.

9. Many homes are built with beautiful brick steps and veneered
brick entrances. Occasionally such brick work is supported by reinforced
concrete, but generally it is supported by wood framing. In a very large
percentage of homes the space under such steps and entrances is not proper-
ly ventilated; and since outside steps and entrance platforms are always
exposed more or less to the elements, moisture leaks through and provides
ideal conditions for the nesting of termites and the development of fungi
(see fig. 19). This also applies to concrete steps and concrete platforms
where they are supported by wood framing. The entrance is generally a
decorative feature, but in a large percentage of the homes inspected the
construction was very bad. Do not fail to inspect your home for such con-
ditions and if necessary consult some one competent to advise you.

10. In constructing garages, the concrete foundation and wood frame
are generally erected prior to the pouring of the concrete floor slabs. We
frequently found that the frame to which the garage doors were hung
extended into the floor slab in ground contact. Be sure that this condition
does not prevail in your garage.

SAN FRANCISCO TERMITE SURVEY 33

1 1 . The basement concrete slab is often poured after the wood steps
leading to the basement and the framing for basement partitions have been
erected, and frequently the bottoms of such steps and wood partitions are
encased in a concrete slab in ground contact. Inspect your house for such
conditions; they should be corrected. This faulty construction has been an
important contributing factor to termite infestation in homes.

12. Rear porches are a common source of termite infestation. Usually
after such porches have been erected, the concrete slab or sidewalk is
poured often encasing the wood in concrete. All framing and wood posts
supporting porches should be cut off above the top of the concrete slabs.
The bottom of posts that support wooden hand-rails should not be encased
in concrete unless the wood has been chemically treated.

1 3. When a house and garage have been substantially completed it is
customary to install the driveway to the garage. It is frequently necessary
to adjust the ground surface to provide an even grade between the garage
and the street, resulting in the raising of the ground surface adjoining the
building. This often results in portions of the wood frame of the home being
placed below the top of the concrete driveway, creating a condition which
favors both termite infestation and damage by fungi.

1 4. Do not lay wood floors on concrete that is in ground contact unless
the wood has been chemically treated. It is impossible to provide proper
ventilation under such a floor, and the wood absorbs a certain amount of
moisture from the concrete which, in turn, absorbs moisture from the ground
beneath. Such concrete slabs usually crack, and these cracks provide ready
access for subterranean termites.

1 5. There should be a space of at least 1 8 inches between the bottom
of the floor joists and the top of the ground surface in the basement. In
many homes this clearance has not been provided, making it exceedingly
difficult to make a proper inspection; and should this condition prevail in
your home, it may be advisable to employ an expert familiar with the
termite problem to make a survey of your home.

16. Fence posts, clothes-line poles, and wood curbs in gardens are
almost universally infested by termites. In a nurnber of cases where the
building itself was not infested we found termites infesting wood in ground
contact in the garden, providing breeding places for these termites. This
was without doubt the most common breeding-ground for termites uncov-
ered in the San Francisco Termite Survey. Wood placed in ground con-
tact should be chemically treated with a preservative that is not water-
soluble, and which is known to be toxic to termites.

1 7. Poorly constructed window boxes commonly result in termite in-
festation and damage to buildings by fungi due to moisture leaking through
and coming in contact with the wood frame of the house. A careful inspec-
tion of all window boxes should be made to determine their potential possi-
bility for damage.

18. Conservatories in homes also frequently are the cause of excessive
dry rot and termite damage. In watering plants, care should be exercised

34

CITY AND COUNTY OF SAN FRANCISCO

to avoid creating a condition of permanent dampness in the wood frame
of your building.

• I 1

(Fig. 27). Bathroom floor 10 feet above the ground, seriously damaged by damp-T»ood
termites. Bathrooms frequently provide conditions favorable for the colonizing
pair of damp-wood reproductives.

19. Termites have been found penetrating brick walls which have
been laid with a lime mortar. As they can easily dig through such mortar,
it is advisable to be generous in the use of cement in laying brick.

20. Do not permit water from the shower-bath to strike the wood work
or plaster on the walls of your bath room. Plaster is rarely watertight, and
permits moisture to reach the wood backing causing the wood to rot, and
frequently providing an available source of moisture for the colonizing pair
of damp-wood termites.

Do not use an excessive amount of water in washing bath room floors
covered with linoleum or tile (see fig. 27). Water thus used often reaches
the wood below, causing damage by dry rot and damp-wood termites.

Leaky plumbing and sweating joints in water pipes are also a common
source of trouble that leads to dry rot and termite infestation (Fig. 28).

SAN FRANCISCO TERMITE SURVEY

35

(FlG. 28). A sweating joint in a water-pipe attached to the ceiling in a basement pro-
vided damp-wood termites with the moisture required to establish a colony. The
subfloor and joists were badly damaged by these insects.

2 1 . Store fronts are very commonly infested by termites. Usually there
is a joint between the sidewalk and the concrete foundation at the building
line. The frequent washing of windows and the hosing of sidewalks per-
mits moisture to penetrate through this joint in the concrete to the soil below,
providing ideal conditions for subterranean termites. Termites then find
entrance through cracks in the slab inside the building where a wood frame
supports the display-space in show-windows. Changes in construction
methods and the use of a small quantity of chemically treated wood will
usually avoid all such difficulties.

22. Do not purchase firewood that is infested with termites or wood-
boring beetles. Both termites and beetles were found swarming from such
infested firewood in basements, endangering the entire structure.

23. Chemicals that are dangerous to human beings or to pets that
might get under the house should not be used for ground treatments to
destroy termites in the soil. If in spite of this warning arsenic is used, the
risk to the user as well as to the home owner should be recognized. Merely
spraying the soil is inadequate; only a thorough drenching of it will pro-
vide any protection. Leaching may follow such drenching of the soil, and
plants adjacent to the house are subjected to serious injury. A conspicuous
permanent label on soil thus drenched should state: "POISONED WITH
ARSENIC.** There are other products which do not present a hazard to

36

CITY AND COUNTY OF SAN FRANCISCO

human life and which, although possibly more expensive than arsenic, will
prove more effective. Soil treatments are not universally effective and too
often create a feeling of false security.

Professor Frank T. Green, City Toxicologist, Dr. C. D. Leake, of
the University of California Medical School, and Dr. Charles A. Kofoid,
Chairman of the Department of Zoology of the University of California,
have this to say:

"Since it has been demonstrated that certain fungi in wood and in
termite burrows can and do utilize arsenic in their food without being killed
thereby, and under these conditions release trimethyl arsine gas, an odor-
less deadly poison, it is advisable to avoid the use of all arsenical com-
pounds either as sprays, ground treatment or wood preservatives in dwell-
• »»
mgs.

Dr. J. C. Geiger, Director of Public Health of San Francisco, pro-
vides a word of caution against the use of arsenic :

"Tri-Methyl Arsenic Gas.

"In view t>f the strenuous efforts exerted in the past and at present by
various health agencies and agriculturists throughout the world in discourag-
ing the use of arsenic and its compounds in any manner whereby it may
affect the public health, it would indeed be a mistake to allow arsenic
compounds to be used in the treatment of premises for extermination of ter-
mites. This is particularly important as the gas given off under particular
circumstances can in no way be detected, and serious symptoms may follow
the inhalations of very minute amounts."

24. In dealing with the termite situation, it is well to remember that
it is not possible to get something for nothing. High-pressure salesmanship
in neighborhoods often creates undue concern in the minds of property
owners. It should be remeimbered always that termites do not create haz-
ardous conditions over night. Hence it is well to investigate before taking
hasty action.

25. Your property should be systematically inspected at least once a
year, and preferably every six months. When repairs or remodeling are
undertaken, every effort should be made to observe practices in construc-
tion which will minimize termite infestation. In other sections of this report
your attention has been directed to the fact that subterranean termites build
tubes or covered runways over masonry or concrete to reach raw wood not
in contact with the ground (fig. 13). When making these systematic in-
spections, therefore, you should search carefully for the presence of such
tubes or runways.

The above suggestions should prove of material aid to home owners
and prospective purchasers. They by no means cover all the technique of
inspection, but will prove helpful.

SAN FRANCISCO TERMITE SURVEY

37

SUMMARY

Living as we are in a changing world, it becomes necessary from time
to time to stop and take stock of these changes, and relate them to existing
conditions. This has been the purpose of the San Francisco Termite Survey,
limited to the influence of wood-destroying organisms on physical proper-
ties brought about by such changes. In this report it has been possible
merely to indicate a few of the changes occurring within our memory. The
influence of certain of these changes, and their contributing effect on the
lowering of the ground waters, has been discussed. Another important
change has been the installation of modern plumbing in our homes. We
found in this survey that leaky plumbing, sweating joints, and poorly-pro-
tected shower baths have also been contributing factors to the infestation of
structures by termites (fig. 28). The important element of moisture so
necessary for the colonization of damp-wood termites and subterranean
termites, is often found in otherwise well-built buildings, due to faulty
plumbing.

Much of the damage being done by termites can be prevented by
proper building requirements. Mention has been made of the fact that
the practice of installing furnaces in homes stimulates termite activity. It
has been said that man's greatest battle in the future will be fought with the
insect world; but thus far we have entirely failed to take account of the
destructive propensities of termites. To acquire esthetic effects, architects
and builders, because of their lack of knowledge of this important sub-
ject, have created conditions most favorable to their development. The
logical sequence now would seem to call for a study of building ordi-
nances, with a view to amending them so that the mistakes of the past will
not be repeated in the future. In correcting the many defective con-
struction details in buildings, little if anything will be added to the ultimate
cost of structures. In most instances the cost of building termites out of
a structure should not add more than 1 % , or at most 2 % , to its cost, and
would result in a better and more durable structure.

There are three major factors which appear mainly responsible for the
widespread distribution of termites within the city limits and have made
termite infestation ' inevitable. Unlike most great cities, San Francisco is
founded on a peninsula, with a limited ground area available for sub-
division purposes resulting in small building lots and a large percentage
of structures being erected in solid rows. Soil conditions in San Francisco
are most favorable for the nesting and propagation of subterranean
termites, while the climate appears to provide ideal conditions for the
colonizing of wood-dwelling termites.

In the past the building industry has failed to appraise the extent of
the problem created by termites. Home ownership is considered one of
the great stabilizing influences in American life. Prospective buyers are
now questioning the advisability of investing their life savings in a home,
having noted the difficulties and experiences of others caused by these
insects. Such people often lack technical information, and usually are
unaccustomed to employing technical advice to preserve their investments,

38

CITY AND COUNTY OF SAN FRANCISCO

as are large corporations. It would seem timely, therefore, to establish
rules through a revised building code governing new construction, and
thus provide the small home owner with this needed information. Caveat
emptor! Let the buyer beware, is becoming the watchword in real estate
transactions. Here again we find the person of small means, unaccustomed
to business transactions, failing to act prior to entering into a contract and
then, often in anguish, seeking help. The new problem presented should
be frankly faced, in the courageous manner that is typical of San Fran-
cisco. For these reasons I would recommend:

1 . That the inherent danger created by the recession of the ground
water level where buildings are supported on wood piling, be explored

. to determine its boundaries; and that the effect of the proposed construction
of the Market Street Subway upon this important problem be considered
also.

2. Emphasis on methods of prevention and control of termite damage
is almost universally applied to infestations by subterranean termites, on the
commonly-accepted assumption that subterranean termites constitute a
predominating economic factor and that damp-wood termites are of minor
importance. The survey of all structures in an area comprising some 662
acres disclosed the interesting fact that damp-wood termites are also
of great economic importance to property owners in our city. The number
of city-wide random inspections, however, was limited, and before it can
be safely assumed that the conditions found in the district completely
surveyed can be applied to the city as a whole, a more adequate sample
survey should be undertaken by the City of San Francisco, or a new
program instituted similar to the one upon which this report is based.
Methods commonly used for the eradication of subterranean termites are
not equally effective when applied to the damp-wood species.

3. A scientific study of our building ordinances in the light of this
growing menace should be undertaken with a view to recommending
methods which will minimize the present inherent danger and prevent
damage to subsequent construction. The need for such a revision can be
illustrated by citing an experience in one of our fireproof buildings: A
concrete trough was constructed on the ground floor of this building
to provide for the installation of conduits and pipes. These electric
conduits were not thoroughly embedded in the concrete where they passed
through the wall and entered the trough. Termites gained entrance
along the conduits and did extensive damage to partitions, filing cabinets,
and paper records. Had it been required in the building ordinance that
tight metal collars be placed on the conduit within the concrete wall,
the termites could not have entered. The cost of such a minor change in
method is negligible, but the cost of the repairs to the building due to
termite damage and the loss of records, was substantial.

4. The work of classifying the soil in detail throughout the city
has not yet been completed and this phase of the work should be prose-
cuted to a conclusion.

5. The practice of selling insect-infested wood to householders should
be controlled.

SAN FRANCISCO TERMITE SURVEY

39

6. Every effort should be made to reduce the available food supply of
termites. The present custom of burying form-lumber in the soil and of
back-filling trenches in the streets, leaving the wood-lagging, should be
avoided. This practice provides potential reservoirs of food for termites,
which tends to increase the density of their population.

7. Further experimentation should be made in the use of lethal electric
rays as a means of destroying larvae of beetles and of eradicating termites
under certain conditions. There also is need for the development of sound
equipment for detecting the presence of termites in concealed places.

o

ACKNOWLEDGMENTS

The relation of the Federal Government to the San Francisco Termite
Survey was advantageously and helpfully represented by Dr. James
B. Sharp, the State Coordinator of Statistical Projects of the Works
Progress Administration; Ralph J. Wakefield, Supervisor of the
Division of Employment; Mrs. Claya Budd, District Supervisor, Women's
and Professional Projects, and Mrs. Florence Chemnick, Assistant Super-
visor, Women's and Professional Projects. Their knowledge of govern-
mental procedure and their desire to cooperate have very greatly facilitated
the progress of the survey.

The cooperation of the City of San Francisco initiated by Alfred
J. Cleary, the Chief Administrative Officer, has been continued by W.
H. Worden, Director of Public Works, Clyde E. Healy, Chief Assistant
City Engineer in charge of relief projects, Erie L. Cope, Superintendent of
the Bureau of Building Inspection, and Dr. J. C. Geiger, Director of
Public Health. These gentlemen gave liberally of their time and con-
tributed many helpful suggestions which facilitated the conduct of the work.
The Building Inspectors under the supervision of Mr. Cope were also of
material aid. The members of the Fire Department and in particular,
Fire Chief Charles J. Brennan and Captain Theodore Trivett of the
Fire Prevention Bureau, made space available to the personnel of the
survey in their fire houses, and in other ways materially aided the project.

The work of moisture determinations was undertaken in the City
Laboratory under the supervision of Dr. C. L. Cook, City Chemist, and
the preliminary studies of the hazard to human health created by the use
of certain chemicals, were made in the laboratory of Professor Frank T.
Green, City Toxicologist.

40

CITY AND COUNTY OF SAN FRANCISCO

Dr. Charles A. Kofoid, Chairman of the Department of Zoology
of the University of California, and Dr. C. D. Leake of the University
of California Medical School, served as an advisory committee to the
work done in the laboratory of the city toxicologist.

Several corporations contributed the time of their employees as well
as furnishing equipment without charge. The Reilly Tar & Chemical Cor-
poration of Indianapolis supplied equipment developed in its engineer-
ing laboratory, illustrated in figure 22, for experimental work in pressure-
treating lumber in a building.

The General Electric X-Ray Corporation made available laboratory
space, equipment and personnel for experiments in the use of Roentgen
Rays, and short-wave apparatus for experiments using lethal electric rays
for eradicating beetles and termites.

The Pacific Gas and Electric Company volunteered the services of
J. P. Jollyman, an eminent electrical engineer, to assist in conducting
experiments involving lethal electric rays.

The relation of the lumber industry to this important survey was
advantageously served by John H. McCallum, president of the Mc-
Callum Lumber Company and M. I. Harris, president of the Van Ars-
dale-Harris Lumber Company.

Special mention should be made of the following members of the
survey staff: E. Ross Ellis, Assistant Supervisor, Dr. Walter R. Shaw,
Professor George Albers, Harry W. Abrahams, licensed architect, who
were largely responsible for the educational program, and M. H. Mc-
Carthy, in charge of the photographic work.

SAN FRANCISCO TERMITE SURVEY

41

APPENDIX

TABLE NO. J

CLASSIFICATION AND NUMBER OF STORIES IN
BUILDINGS INSPECTED

Number of Number of Number of Number of

Number of Wood Frame Class "C" Class "B" Class "A"

Stories Buildings Buildings Buildings Buildings

Inspected Inspected Inspected Inspected

1 story 227 182 14 1

1 story and basement 74 72 2 2

2 stories 131 116 8 8

2 stories and basement 1 67 115 18 4

3 stories 65 27 6 1

3 stories and basement 77 102 12 4

4 stories 4 16 2 2

4 stories and basement 14 56 5 3

5 stories 3 4

5 stories and basement 28 13 7

6 stories 7 2 1

6 stories and basement 25 14 3

7 stories 1 3 1

7 stories and basement 8 8 3

8 stories

8 stories and basement 2 5 3

9 stories and basement .... 2

10 stories and basement 1 4 3

1 1 stories and basement .... .... 2

12 stories .... .... 1

14 stories and basement .... .... 2

16 stories and basement .... .... 2

1 7 stories and basement .... .... 1

18 stories and basement .... .... 3

21 stories and basement .... .... 1

22 stories and basement

26 stories and basement .... .... 1

Lumber Yard 1

Rustic Bridge 1

Kezar Stadium 1

Rustic Horse Stalls 2

Rustic Pavilion

765

761

123

61

42

CITY AND COUNTY OF SAN FRANCISCO

TABLE NO. 2

SUMMARY OF BUILDINGS INSPECTED

In this area, comprizing approximately 662 acres, 100% of the buildings

were inspected

Total Class Class Class Wood
Number A1 B2 C8 Frame

KIND OF INFESTATION Inspec- Build- Build- Build- Build-

tions ings ings ings ings

Number of inspections made . 1385 44 103 678 560

Number of damp-wood termite

infestations 2 3 59 130

Number of damp-wood and

beetle infestations 1 .... 5 4

Number of subterranean

termite infestations 2 13 115 1 63

Number of subterranean and

beetle infestations 114 2

Number of subterranean and
damp-wood termite infesta-
tions 2 4 16 122

Number of subterranean and
damp-wood and beetle in-
festations .... 2 1 1

Number of damp-wood, dry-
wood and beetle infesta-
tions

Number of infestations by bee-
tles only 4 14 10 5

Number of buildings damaged

by fungi only 1 8 111 52

Number of buildings where no
kind of wood-destroying or-
ganisms were found 31 60 356 71

Per cent of buildings infested

by wood-destroying insects 27% 34% 31% 78%

Per cent of buildings infested
by wood-destroying organ-
isms 30% 42% 48% 87%

Per cent of infestations where
damp-wood termites were

present 42% 20% 39% 61%

Per cent of infestations where
subterranean termites were

present 42% 51% 65% 68%

Per cent of infestations where

beetles were present 50% 43% 10% 5%

i, 2, 3 — For definition of building types, see page 44.

SAN FRANCISCO TERMITE SURVEY

43

TABLE NO. 3

SUMMARY OF CITY-WIDE RANDOM INSPECTIONS

Grand
Total of
Build-
ings
Inspected

1710

Total

Number

Class

Class

Class

Wood

of

A

B

C

rrame

KIND OF TNFF STATION Tnmer-
rv i i > \-j wr i.i>r i-aj i r\ x inspec-

Build-

Build-

Build-

Build-

tions

ings

ings

ings

ings

Number of inspections made 325

17

20

83

205

Number of damp-wood ter-

mite infestations

1

4

4

44

Number of damo-wood and

beetle infestations

5

Number of subterranean ter-

8

7

22

77

Number of subterranean and

beetle infestations

3

8

Number of subterranean and

damp-wood termite in-

festations .

3

32

Number of subterranean,

damp-wood and beetle

infestations

1

1

9

Number of damp- wood, dry-
wood and beetle infesta-
tions .... .... 2

Number of infestations by

beetles only .... 6 5

Number of buildings dam-
aged by fungi only 1 13 14

Number of buildings where
no kind of wood-destroy-
ing organisms were found 7 8 31 9

Per cent of buildings infested

by wood-destroying insects 59% 55% 47% 89%

Per cent of buildings in-
fested by wood-destroy-
ing organisms 59% 60% 63% 96%

Per cent of infestations where
damp-wood termites were

present 20% 36% 20% 50%

Per cent of infestations where
subterranean termites were

present 90% 64% 74% 69%

Per cent of infestations where

beetles were present 10% .... 26% 16%

44

CITY AND COUNTY OF SAN FRANCISCO

RECAPITULATION OF TOTAL INSPECTIONS AND
INFESTATIONS SHOWING THE PERCENTAGE
OF INFESTATION IN EACH CLASS OF
BUILDING, TAKEN FROM TABLES
NO. 2 AND NO. 3

Of 61 Class A Buildings, 22 or 36% were infested by wood-destroying
insects.

Of 123 Class B Buildings, 46 or 37% were infested by wood-destroying
insects.

Of 761 Class C Buildings, 250 or 33% were infested by wood-destroying
insects.

Of 765 Wood Frame Buildings, 618 or 81 % were infested by wood-des-
troying insects.

1 Class "A" Buildings are defined by the San Francisco Building
Laws as those having fireproof frames of steel and with all structural parts
of incombustible materials. Walls shall be of brick, stone, concrete or
reinforced concrete.

2 Class "B" Buildings are defined by the San Francisco Building
Laws, as those having a frame of reinforced concrete carrying all wall and
floor loads. All structural parts shall be of incombustible material. Walls
shall be of brick, stone or reinforced concrete.

3 Class "C" Buildings are defined by the San Francisco Building
Laws, as those having exterior walls of brick, stone or concrete, and an
interior frame of combustible material. The walls may be bearing or curtain
walls, and the interior supports may be timber joists, timber or steel girders
and timber, steel or cast iron columns, or timber studding.

SAN FRANCISCO TERMITE SURVEY

45

TABLE NO. 4

LOCATION OF INFESTATIONS IN THE BUILDINGS

INSPECTED.

\V 7 ]

Wood

f rcinic

Class C Class B

Class

Buildings in ground contact *

416

615

103

O 1

Buildings where wood is placed within

1" to 3" of the ground

38

3

1

Buildings with termite-infested wood sills

274

32

1

Buildings with termite-infested wood

posts

168

45

2

i
1

Buildings with termite-infested wood

joists

192

45

2

i
1

Buildings with termite-infested wood

-

studs

249

45

2

—

Buildings with termite-infested exte-

nor walls

*■"» A A

244

43

10

A

Buildings with termite-infested interior

walls

80

7

5

Buildings with termite-infested stairs

and porches

235

38

1

4

Buildings with stairs infested by fungi

only

89

....

Buildings with termite-infested flooring..

196

69

6

3

Buildings with infested upper floors:

Second floor

35

18

3

Third floor

14

7

2

Fourth floor

3

2

3

....

Fifth floor

4

1

Sixth floor

i

Seventh floor

T

Roof of a 1 0-story building

i

Termite-infested fences, posts, wood

driveways, etc

325

38

6

i

*Some of the wood in the frame buildings listed was in ground contact. Class
A, B and C buildings having first-floor slabs in ground contact are included in this
classification.

46

CITY AND COUNTY OF SAN FRANCISCO

ADDITIONAL DATA COMPILED FROM INSPECTION

REPORTS

Twenty-four buildings had been repaired during the year 1934 due
to termite damage, and of this number 22 were found infested at the time
the inspection was made.

Forty-four buildings had been repaired during the year 1935 due to
termite damage, and of this number 34 were found infested at the time the
inspection was made.

In 30 instances defective plumbing contributed directly to termite in-
festation.

In 37 cases termite infestation was traceable to concrete form-lumber
left in place.

In 17 instances leaky roofs contributed to infestation by termites.

In many of the older Class C buildings, wooden elevator guides were
used, and in 30 of such instances elevator guides and/ or shafts were found
infested by termites.

Permanent dampness caused primarily by poor drainage was found in
the basements of 31 3 buildings.

In the basements of 442 buildings, debris, such as lumber, boxes, paper,
etc. (all of which contribute to termite infestation) was found.

Termites were found entering concrete or masonry walls in Class A,
B and C buildings through defective concrete, cracks in concrete or brick
walls, cracks in concrete floor slabs, wood-block spreaders, loose steel tie-
wires in concrete walls, and along water lines, sewer pipes and electric
conduits.

In the basement of one Class C four-story building, subterranean ter-
mites gained entrance through wood spreaders left in the concrete walls, at
20 different locations and built covered runways to the wood joists above.

In a number of instances trees and old stumps in the yard were infested
by termites, affording these insects with conditions favorable to the develop-
ment of colonies adjacent to buildings.

Leaky sidewalk lights provided necessary dampness in basements for
the colonizing of termites in paper cartons and newspapers piled five feet
six inches above the floor.