PENETRABILITY OF SOME ONTARIO CONSTRUCTION AGGREGATES BY THE EASTERN SUBTERRANEAN TERMITE (ISOPTERA, RHINOTERMITIDAE)

Ontario populations of the eastern subterranean termite, Reticuliterme s flavipes (Kollar) were tested for their ability to penetrate various types of soil, sand, and common construction aggregates. Of seven who le aggregates that were evaluated, six were readily penetrated because the particle sizes were either too coarse or too fine or had too few particles in the effective particle size range to serve as a barrier t o termite tunnelling. Only one of the whole materials, a crushed limes tone (WP2 sand), prevented termite penetration. The termites most read ily penetrated coarse gravel, with particle diameters greater than 3.3 5 mm, by crawling through the interstices between the particles, trave rsing a six centimeter layer in one day. They also readily passed thro ugh fine sand, with particle diameters less than 0.71 mm, by excavatin g particles with their mandibles, tunnelling through a six centimeter layer in two to three days. Penetration was delayed from four to six d ays in sieve fractions with particle diameters greater than 0.71 and l ess than 1.0 mm. Sieve fractions from 1.0 to 2.0 and 2.0 to 3.35 mm we re impenetrable. Although the particle size range of some commercial s and barriers products have been more narrowly constituted, these resul ts show that either crushed or natural aggregate mixtures, with broade r particle size ranges from 1.0 to 3.35 (100% passing Mesh 6 and 0% pa ssing Mesh 18) can serve as effective barriers to subterranean termite s. These wider particle size ranges may reduce production costs and th ereby promote wider commercial development of sand barriers. Other asp ects of the commercial development of sand barriers for termite contro l are also discussed.