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 repeatedly used by succeeding generations, it may ultimately reach 6 to 10 feet in length.
Damage from carpenter bees can be prevented by keeping wood surfaces well painted. Interior un-
painted surfaces should be protected by keeping windows and doors closed or screened during the
spring and early summer when the bees are looking for a nesting site.
Wood pressure-treated with organic preservatives, such as pentachlorophenol, or with heavy load-
ings of water borne preservatives, is resistant to carpenter bee attack. Even surface coatings of or-
ganic preservatives are helpful. In order to maintain the repellent effect, the surface should be
retreated when it has weathered for several years.
Five to 10 percent carbaryl (Sevin) dust, or any insecticide labeled for bee control, applied into the
entry holes will kill bees which come into contact with the residue. Several days after treatment, the
holes should be plugged with short lengths of dowel rod of the proper diameter, or with plastic
wood. Plugging the holes without applying insecticide can lead to the production of new holes next
to the plugs when bees inside attempt to emerge, or nesting females seek re-entry into galleries in
use.
Treating the external surfaces in the vicinity of the entry holes with 0.5 percent lindane oil solution,
or with any insecticide labeled for bee control, will discourage continued bee activity for the season.
4.4 MARINE BORERS. Marine invertebrates which bore into and, consequently, damage timber
in salt or brackish water are called marine borers. Marine borers are serious pests in wooden
waterfront structures (Figure 4-30) and have damaged wooden vessels throughout history. A sum-
mary of the characteristics is given in Table 4-4.
The marine borers which cause the greatest amount of damage can be divided into two main groups.
Members of the phylum Mollusca constitute one group. These organisms are shell animals like
clams and oysters. The Molluscan borers are further divided into two families. Teredinidae which
contain the genera Teredo and Bankia are commonly called wood-boring shipworms. The second
family is called Pholadidae and includes the genus Martesia and resembles clams and is commonly
referred to as Pholads or rock boring piddock. The second major group belongs to the phylum Crus-
tacea and are related to the lobsters and crabs. Limnoria and Sphaeroma are important wood-
destroying genera. Limnoria are commonly referred to as gribbles.
Marine borers vary greatly in their distribution (Figure 4-31) and ability to destroy wood. They are
generally more destructive in tropical waters. Their population can rise and fall depending on any
number of factors such as salinity changes due to floods or other causes, water temperatures, and
dissolved oxygen content. There is some indication that marine borer populations increase as pollu-
tion levels decline. Because of this variation, it is always best to consult local authorities before in-
itiating control procedures.
4-50
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