Insect-Proofing During Building Construction

INSECT-PROOFING DURING BUILDING CONSTRUCTION

W. EBELING * R. E. WAGNER - D. A. REIERSON

TRUCTURAL AND HOUSEHOLD PEST mental evidence of efficiency of soil treat- foundation walls or piers. Specific in- S CONTROL in the United States re- ment have been the investigations of the structions for treatment for slab-on- quires annual expenditures of hundreds Southern Forest Experiment Station of ground, raised-foundation, and basement of millions of dollars and the services of the Forest Service, U. S. Department of construction may be obtained in publica- 27,000 licensed pest control operators. Agriculture. These investigations showed tions of the federal or state agricultural Preventive measures against structural that currently recommended dosages of experiment stations or among the tech- and household pests should be taken dur- certain chlorinated hydrocarbons formed nical releases of the National Pest Con- ing the construction of a building, be- a compIetely effective barrier against sub- trol Association. cause such measures are most effective terranean termites for a period of 18 and economical at that time. Preventive years in heavily infested forest soil in Prevention measures fall into two general categories, Mississippi, and may continue to be effec- Some househoId pests, including cock- depending on whether they are directed tive for many more years. The pest con- roaches, silverfish, odorous house ants, against (1) subterranean termites, which trol industry has successfully used soil plaster beetles (Lathrididae) , psocids, invade a building from colonies in the treatment for many years. and rat mites, spend all or a major part soil and which first attack in the sub- Currently recommended insecticides, of their time in hidden areas of a house structure; or (2) a number of other in- and concentrations include 0.5 per cent such as the attic, wall voids, soffit voids, sect species that spend either all or a aldrin, dieldrin, or heptachlor, or 1 per or in voids under cabinets or built-in considerable part of their life in the attic, cent chlordane. The dosage of dilute appliances. In larger apartment and com- wall voids, or in other enclosed spaces in emulsion recommended is 1 gallon per mercial buildings these pests often live various parts of the building. Construc- 10 sq ft as an overall treatment where also in suspended ceilings, hidden radi- tion procedures and other measures to slab and attached porches are to be ators, underfloor raceways for electrical prevent insect attack and damage differ poured, 4 gallons per 10 linear ft along and telephone wiring, elevator shafts, and considerably depending on which of the foundation walls, and 2 gallons per 10 in other hidden floor-to-floor and room-to- groups of pests they are directed against. linear ft in the voids of all unit masonry room passageways. Other pests such as Termites Gravel on which concrete slab is to be poured, and pipe and Soil treatment consists of applying forms, are sprayed with a dilute emulsions of insecticides to the long-lasting residual insecti- soil (see photo). The insecticides and cide in photo below. Pressur- dosages to be used are those recom- ized water-type fire extin- mended by federal, state, and industry guisher used for wall applica- agencies. The greatest sources of experi- tions of dusts for insect-proofing during construction.

4 CALIFORNIA AGRICULTURE, MAY, 1969 Insect proofing at the time of construction offers new challenge and opportunity the treatment of wall voids, soffit voids, to the building and pest control industries. It provides the opportunity for preven- and voids under cabinets and built-in ap- tion, which is generally less expensive and always more satisfactory than cure. pliances at the time of construction. Spe- cial equipment was designed to blow the Some insects such as house flies and mosquitoes are not amenable to control by dust into these voids. Dri-die can be this method-their control is primarily a community or regional problem. Some blown under built-in ranges and refrig- other insects such as ants, sowbugs, fleas and clover mites, may gain entry into erators as a protection against cock- buildings through areas where they don’t have to cross the inorganic powders roaches, silverfish, and other cryptobi- applied during construction. Nevertheless, insect proofing during construction pro- otic insects. Against cockroaches Dri-die vides the means by which a high degree of long-term control of certain important works mainly as a repellent, because most structural and household pests can be effected. of these insects will avoid contact with the dust. However, treated areas are thus eliminated as harborage and breeding drywood termites, carpenter ants, Argen- widely used by termite operators for the places for this important pest. tine and other ants, and wood wasps control of drywood termites. No other Boric acid (Siricidae), may crawl over the inner desiccant is known to have such high in- surfaces of these voids in search of nest- secticidal activity and such low bulk Recent work has shown the superiority ing sites or to reach the “living space” of density as Dri-die 67. The dust is blown of boric acid powder for cockroach pre- the building. When leaving their larval into attics, usually from the crawl hole, vention when applied at the time of con- tunnels in the studs, wood wasps enter at the rate of 1 lb per 1000 sq ft of attic struction. Boric acid has been the least and leave the wall voids through the wall space. It may be applied with an electric repellent to cockroaches of all powders plaster. Both types of pests may succumb blower or water-type fire extinguisher. tested. The insects will repeatedly enter to an insecticide applied uniformly over The dust is usually applied after a fumi- deposits of boric acid and, if the boric surfaces that are likely to become infested. gation, or after other treatment for dry- acid is thoroughly applied, they can be Insecticides can be most rapidly and wood termites to prevent further infesta- satisfactorily controlled. (See Cdifornia thoroughly applied as dust formulations. tion. The Dri-die 67 cannot destroy the Agriculture, Feb. 1969.) Like Dri-die, Also an insecticide deposited as a dust termites in their galleries in the wood- boric acid powder is inorganic and its rather than as a spray is less likely to be this must be done by other types of treat- insecticidal action will continue as long lost by penetration into the treated sub- ment such as fumigation-but it can pre- as it is left in place and remains dry. The strate (wood, Masonite, plaster, brick, vent the winged reproductives which application of boric acid is particularly etc.) and therefore it possesses longer leave the infested wood in the fall months, appropriate in areas of a building in residual efficacy. or those which enter the attic from the which cockroaches are expected to be the outside, from establishing new colonies principal pest. Inorganic dusts in the attic. Even though not all the ter- The application of dust into voids and Ideally an insecticide dust applied to mites are killed in their galleries by a enclosed places at the time of construc- areas in which it can remain indefinitely treatment, the proliferation of colonies tion can be done with a water-type fire should be inorganic, for such a dust, within the attic will be prevented. extinguisher that is now commercially since it cannot be lost by decomposition, The practice of protecting exposed available. The entire contents (3 gallons) may be able to indefinitely eliminate wood members of a structure from attack of the extinguisher can be blown out with structural voids as harborage and breed- by drywood termites by applying a film one pressurization with air to 100 p.s.i. ing places for cryptobiotic insects. With of Dri-die dust was extended to include This kind of blower generates air of this goal in mind a procedure was devel- oped for blowing an inorganic desiccant Ground-level frame duplexes at Ventura Town House were also insect-proofed at time of construc- dust into attics for prevention of drywood tion (see cover photo). termites, Incisitermes minor. Desiccant dusts kill insects by absorbing a portion of the thin protective layer of lipid that covers the entire body surface of an insect (with most insects this consists of a hard wax, averaging about 0.25 micron in thickness, but cockroaches are covered with a mobile grease about 0.G micron thick). When the lipid layer is removed, a lethal rate of water loss results. Dry- wood termites most commonly enter into houses via the attic. A thin film of desiccating dust over the entire inside surface of an attic prevents thein from even at- tempting to attack the dusted wood, and in fact they die within a few hours. In 1958 a fluorinated silica aerogel which later became known as Dri-die 67, was found to be the most highly insecticidal of the desiccating dusts and is now

CALIFORNIA AGRICULTURE, MAY, 1969 5 enough velocity and volume to dust attics tive areas for cockroaches. A layer of dust where cockroaches can be expected to be as well as wall or subcabinet voids. under and behind these appliances will a dominant problem, Dri-die should prob- When dusting wall voids that have no eliminate them as harborage and breed- ably be applied only in attics and wall insulation or fire blocks, one should inject ing places. voids, to keep cockroaches from living the dust upward from about 4 or 5 ft The seven-story concrete building (see and breeding in these areas and to pre- above the floor level through +&inch photo) contains a large kitchen, storage vent them from moving from room to holes made in the plaster lath with a small room, and dining room. Dri-die was ap- room or apartment to apartment through geologists’ pick (see photo). When fire plied wherever possible during construc- the wall voids. Boric acid would be most blocks are present, the dust should be ap- tion. However, the many structures and effective in such places as sub-cabinet plied from any convenient level below appliances later brought into these rooms voids, under built-in ranges and refriger- the blocks. The dust is deposited on the offered harborage for cockroaches so they ators, under pallets and behind piles of underside of the ceiling plate or fire block were also treated with boric acid powder. boxes in storage rooms, and on the shelves and on all other surfaces between the two of cabinets, pantries, and closets. studs, leaving the heaviest deposit on the Complete program In the seven-story apartment complex floor plate. By directing the dust down- Soil treatment and insect proofing of shown in the photo, the “insect-proofing” ward from approximately the 3-ft level, buildings have been described as two with Dri-die was completed in November the floor plate can be covered despite distinct procedures because equipment, 1964. Boric acid powder was applied insulation in the walls. insecticides, and methods of application later in the kitchen and storeroom under The outer wall can be effectively are quite distinct in these two types of and behind appliances and cabinets, treated by making holes through the “built-in” pest control. However, most under pallets in the storeroom, and in the building paper and blowing the dust into pest control operators have, or can read- pit under the dumb waiter (although it the wall voids from the outside. ily obtain, the necessary equipment and had been previously treated with Dri- Usually 1% lbs of Dri-die is required they have ready access to the insecticides die). In the nearly five years since con- per 1,000 sq ft of structure. A +&inch required. The two procedures should be struction, the kitchen-storage room area hole should be drilled at the top of each combined into a complete program of in- has been free of any noticeable infesta- kick panel under cabinets, and the sub- sect proofing at the time of construction tion of cockroaches. cabinet voids, as well as spaces under any to eliminate, or at least reduce, the sever- built-in appliances, should be dusted lib- ity of a wide variety of insect problems. Cockroaches erally, bringing the total amount of dust Occasionally localized pest problems may During 1967 and 1968 cockroaches used to about 1v2 Ibs per 1,000 sq ft of occur in an insect-proofed building. For were found in seven apartments in the floor space. In residential construction example, if the refrigerator and range apartment building and were treated. the attic should also be dusted, using 1lb are not built in, a protective layer of dust The cockroaches apparently gained ac- per 1,000 sq ft. Where boric acid is ap- cannot be applied under these appliances cess to the apartments through the trash plied, greater quantities are required be- during construction. Cockroaches acci- chute that connects each floor of the cause of the much greater bulk density dentally introduced in cartons or pack- building to a basement trash room. Cock- of this powder. ages containing foods or beverages, or roaches were found in the trash room, by various other means, may then become which had not been treated at the time Apartment application established. However, treatment of such of construction. Many opportunities ex- Some modification of the above pro- infestations is much simpler and more ef- isted for dusting this room under pallets cedure is necessary for “drywall” con- fective if the principal harborage and and in subcabinet voids, behind piles of struction. An example is the insect pre- breeding places for these insects have al- boxes, etc. The room was treated with ventive measures that were taken in Ven- ready been treated with an inorganic boric acid in September 1968 and no new tura, California, at the time of the con- insecticide dust at the time of construc- infestations have been reported since that struction of the Ventura TowneHouse. tion. treatment. The TowneHouse consists of 331 apart- The prevalence of the cockroach as a The almost complete absence of cock- ments in a seven-story concrete building household pest poses the question as to roaches in this apartment complex dur- and 10 one-story, wood-frame apartment whether boric acid powder should be ing a period of nearly five years is par- buildings (see photo). Holes were drilled used instead of Dri-die in hidden areas. ticularly significant in view of the rapid- for the injection of dust onIy along the Dri-die is the more insecticidal powder ity with which these insects normally lines where sheets of drywall (sheetrock) against the largest number of pests; but infest such buildings. Cockroaches are were joined. The junctures of the sheets boric acid has the advantage of being generally considered to be the first in- were taped over after the dust was ap- much less repellent to cockroaches. As a habitants of any new building-arriving plied. result, a greater number of insects will to feed on the remains of the lunches of In addition to the wall voids, the voids enter areas dusted with boric acid and be the construction workers. However, the under cabinets were dusted through holes killed. Treated areas are not only elim- only insects that have presented a prob- drilled at the top of the kick panels. The inated as harborage and breeding places, lem in this apartment-house complex holes were concealed by the horizontal as with Dri-die, but are effective traps have been Argentine ants and sowbugs extension of the door of the cabinet over that substantially deplete the cockroach which come in from the outside, particu- these panels. Dust was also blown population in the “living space” of a larly under sliding doors. These have through the usual access panels into the building. It is possible that boric acid been controlled by the gardener. enclosed area around the bathtub which might be as effective as Dri-die against a Insect proofing of a restaurant in Santa contains the utility pipes. Dust was also wide range of insects. For example, a Ana during construction was strikingly applied under built-in ranges and refrig- minute film of boric acid on wood will successful using only boric acid. Nine erators which are generally very attrac- prevent drywood termite attack. In areas pounds of boric acid was applied in July,

6 CALIFORNIA AGRICULTURE, MAY, 1969 1968. Powder has since been reapplied when it was occasionally removed in cleaning operations, or when it became wet, but this minimal maintenance program has resulted in satisfactory control. CROOKED Several treatments Insect proofing requires several trips to the construction site. To control subterranean termites, soil should be treated CALF before the foundation is poured. In the case of slab-on-ground foundations a single treatment may be sufficient if a monolithic slab foundation is poured. DISEASE Two treatments may be necessary if the footing and the remainder of the slab are poured in two separate operations. An- other treatment should be made just be- Crooked calf characteristics shown above in- fore the concrete cap is poured on earth- clude enlarged knees on the front legs which CARL W. RIMBEY filled extensions of the foundation such are bent forward. The neck also is not natural as steps, stoops, porches, patios, terraces, and shows some effects of this malady. etc. Approximately half of the subterranean termite infestations originate under earth-filled extensions of the foundations; the termites gain entry to wood structures through cracks that eventually appear be- LUPINE-CROOKED CALF TEST, RAMELLI RANCH tween the concrete caps and the main PLUMAS COUNTY foundation. For raised-foundation con- Cow No. Date born Description 758 March 15th Very croaked legs, back-died at birth struction, another insecticide application 515 March 20th Very crooked legs and back-died at birth should be made after floor construction 111 March 26th Very crooked back & legs-died at birth Ear Tag 42 March 1 lth Crooked front legs-Average is complete and after wood scraps are 211 March 13th Crooked front legs-Average cleared out from under the building. At 908 March 13th Crooked front legs-Average 201 March 28th Crooked front legs-Average-Died April 17 this point the area under the floor should 312 March 14th Croaked front legs (great) and slight back also be treated. 772 Morch 21st Very crooked front legs 016 March 20th Crooked front legs-Average Dust should be blown into the wall 221 March 15th Right front leg crooked voids during the interval between the in- 410 March 25th Both front legs crooked-Average 773 April 1st Both front legs crooked-Slight stallation of the plaster lath or drywall 92 1 March 22nd Right front leg crooked-Very and the plastering or taping operations. 774 March 15th left front leg crooked-Sidewinder It is the only procedure in which timing 907 March 29th Both front legs crooke&Slight is a critical factor. The remainder of the insect-proofing operation is best done after construction is complete and before the final cleanup. The pest control operations must be scheduled at appropriate ROOKED CALF DISEASE has been a termine whether the lupine was in fact times during construction operations in Cproblem in the northeast mountain causing the crooked calf disease. This order to obtain thorough treatment. An counties of California for many years. ranch had a history of crooked calves, agreement on this point should be a part Calves are born with this malady and it is with as many as 25 per cent of a calf crop of the pest control operator’s contract demonstrated by malformations of bones showing some stages of this malady. with the builder and construction firm. In in the animal which have a severe to slight certain buildings or in localities where crippling effect. Calves may have twisted Plumas ranch cockroach infestation is practically cer- backs or necks, twisted or bowed legs, The Ramelli Ranch is located in Sierra tain and where the range and refrigerator cleft palates or combinations of all of Valley of Plumas County with a summer are not built in at the time of construc- these effects. range 10 miles north of the ranch. The tion, boric acid powder should be applied For years it has been felt that the summer range lies west of Frenchman under these appliances when they are lupine plant, when eaten during certain Reservoir and is heavily infested with installed. stages of pregnancy, is causing this dis- lupine. The cattle were pastured in this ease. Ranchers of the area have changed area from July 1 to September 30 of the Walter Ebeling is Entomologist and their breeding season and moved their 1967 grazing season. Elevation of this Professor; Robert E. Wagner is Associate cattle from pastures which they know range is around 6,000 ft. Part of the Specialist; and DonaLd A. Reierson is are contributing to the problem, to re- range is privately owned while the re- Laboratory Technician, Department of duce the number of calves affected. A mainder is under U. S. Forest Service Agricultural Sciences, University of Cali- test was designed in 1967 on the Ted permit. The privately owned field was fornia, Los Angeles. Ramelli Ranch, Plumas County, to de- inspected in May, 1967, and a low-grow

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