Common name: a Drywood termite
Scientific name: Cryptotermes cavifrons Banks (Insecta: Isoptera:
Kalotermitidae)
Termites of the genus Cryptotermes were sometimes called
powderpost termites because of the telltale heaps of fecal pellets (frass)
that accumulate beneath infested wood. Fecal pellets of Cryptotermes,
however, are similar in size and shape to other comparably sized species
of Kalotermitidae. All are now collectively known as drywood termites.
The most economically significant termite in this genus,
Cryptotermes brevis (Walker), commonly infests structures and
was at one time known as the “furniture termite,” thanks to the
frequency with which colonies were found in pieces of furniture. A
member of the same genus that might be mistaken for C. brevis
upon a first, cursory examination is C. cavifrons, a species
endemic to Florida.
Cryptotermes cavifrons has an unusually broad distribution for a
Cryptotermes species. It ranges from the Florida peninsula to the
Cayman Islands, Cuba, the Bahamas, Jamaica, and Turks and Caicos
islands. Records from Puerto Rico, St. Croix, Haiti and Central America
are erroneous.
Cryptotermes cavifrons is endemic to all of peninsular
Florida, from St. Johns County south, unlike C. brevis, which is
suspected to have been introduced through the Florida Keys in the early
1900s. Cryptotermes cavifrons is common in dry, dead trees, logs,
stumps and branches, but it is rarely found infesting structures, due to
higher moisture requirements than those of C. brevis. A 2002
termite survey of state parks in central and southern Florida found that
45 percent (18 of 416) of all kalotermitid samples taken were C.
cavifrons.
Because termite workers are indistinguishable from each other to the
level of species, most termite keys rely on characteristics of soldiers
and alates (winged, unmated reproductives) for species identification.
Like all kalotermitids, the pronotum of the C. cavifrons
soldier is about as wide as the head. The head features a large cavity
in front (hence the species name, cavifrons), nearly circular in
outline from an anterior view, shaped almost like a bowl. The rest of
the upper surface of the head is smooth, as contrasted with the
head of C. brevis, which has a similar cavity, but a rough
and bumpy dorsal surface. The soldiers use their heavily sclerotized,
plug-shaped heads (a condition known as phragmosis) to block entrance
and exit holes to the nest. This is their primary mode of defense.
Soldiers are 3.5 to 5.0 mm long. Their head capsules are black at the
front and gradually more reddish toward the back. The rest of the body
is brownish yellow with pale yellow legs and nearly white antennae.
Unfortunately for those wishing to identify C. cavifrons by its
soldiers, it may be difficult to obtain a sample as soldiers make up
only 1 to 2 percent of a colony.
soldier
Close-up of soldier
Alates are approximately .5 to 9.8 mm long, including wings. The
head and body are dull, pale brown. The width of the head is less than 1
mm, and the antennae are much longer than the head, with 10 to 14
(usually 11 or 12) segments. The wings have three to four sclerotized
(hardened and thickened) veins visible in the third of the wing closest
to the body. The forewings also have an unsclerotized median vein that
curves upward to the sclerotized veins about midwing. The wings are
long, with the tip of the abdomen often reaching only about halfway down
the length of the wing. The wing scale (the darkened base of the wing
where it attaches to the body) is often about the same length as the
pronotum.
Close-up of wing
Drywood termites, like all termites, are eusocial insects. They live in
colonies and cooperatively care for young. Responsibilities for
reproduction, foraging and colony defense are divided up among castes:
reproductives (king, queen and alates), workers and soldiers. In drywood
termites, the “worker” caste does not consist of true workers that are
reproductively sterile and found in the higher termites of the family
Termitidae. Rather, immature termites do the labor of the traditional
worker caste, and they are known as pseudergates (“false workers”). All
the casteshave chewing mouthparts, although the mandibles of the
soldiers are greatly modified for defense to the point that they must be
fed by the pseudergates. All but the reproductives are blind.
castes
As with other drywood termites, C. cavifrons gradually
constructs a maze of meandering interconnected galleries. The brood
(eggs, larvae and young pseudergates) are found in some of them — an
indication that the king and queen are nearby.
After the eggs hatch into larvae and go through about three molts,
the young begin the process of separating into castes. Some molt into
presoldiers, which resemble soldiers in form but are unsclerotized and
thus white in color. Others become nymphs, which will eventually develop
into winged reproductives, or alates. Other larvae molt to become the
worker class of the colony, taking care of excavating galleries keeping
the soldiers fed. Drywood termite pseudergates are different from
subterranean termite workers in that they can continue to develop into
alates should a need arise in the colony. In the family Termitidae,
workers are sterile adults, and the path to that caste is a one-way
street. Once a worker, always a worker.
nymph
Eventually, nymphs molt into alates. Swarms occur when these alates
leave the colony to start new colonies elsewhere. Cryptotermes
cavifrons is an unusual species in that alates are present in
colonies throughout the year. Swarms occur in the evenings all year
long, but the peak swarming time is March through May. Termites are weak
fliers and tend to flutter about on the wind as much as actively fly. It
is likely that they will not stray too far from the original colony in
their dispersal flights.
When alates land, they twist off their wings, find a mate and burrow
into a suitable location in the wood such as a knothole or crevice and
mate. Alates who have broken off their wings are called dealates. Eggs
then take several months to hatch.
dealate and alate
Drywood termite colonies develop slowly. The entire colony may take
five years or more to mature. Limited space and resources prevent them
from even attempting the rapid growth of subterranean colonies. Even
with optimal resources, the growth rate of drywood colonies is slow due
to their low inherent reproductive rate. Drywood termites' legs are
actually shorter than subterranean termites' legs, as well, and they
literally move slower as a result. Also, in their preferred habitat,
water is a precious resource in limited supply at certain times of the
year. Drywood termites have several adaptations for conserving as much
water as possible. Three pairs of rectal glands compress their feces to
remove and retain all water possible before waste excretion. This
results in hexagonal fecal pellets (frass). These six-sided pellets,
usually found in small piles, are indicative of drywood termite
infestation. In C. cavifrons termites, the pellets are small and
feel like grains of coarse sand when rubbed between the fingers. Drywood
termites depend heavily on production of metabolic water.
 frass
Galleries cross the grain in wood, but the colony remains confined to
that wood with only alates emerging during flights. No contact with the
ground is necessary for a Cryptotermes cavifrons colony to become
established.
External signs of damage are elusive with drywood termites. Often,
the only obvious signs of infestation are little mounds of fecal pellets
building up underneath the infested wood or the appearance of "kick-out"
holes in the surface of the wood. Drywood termites make tiny holes in
the surface of the wood that allow them to expel their fecal pellets.
Cryptotermes cavifrons soldiers can quickly plug the holes with
their phragmotic heads if necessary. Some holes also may be closed off
with a temporary paperlike substance. These holes are usually very
difficult to see because they are very small (about 1 mm) and seldom
open. The diameter of the frass piles is proportional to the height of
the kick-out holes. Homeowners frequently mistake frass piles for
sawdust.
Drywood termite infestations are difficult to deal with. Most of the
time, infestations are localized, as colonies live entirely with a
particular piece of sound, dry wood. But sometimes the infestation is
not noticed until the colony has matured and produced alates that have
already begun new, undetectable colonies in wood nearby. Localized
treatment of the first colony then does nothing about the second or
third that may already be developing. Treatments are divided into
several types: whole structure; compartmental, such as an attic; and
local, such as a windowsill. They range from fumigation and excessive
temperature to wood injections and localized electrocution. Each method
has its own pros and cons. Preventative treatments are generally made
only when there has been a prior treatment for an infestation. To learn
more about Drywood termite management, please see
Drywood Termite Control: Weighing All the Options.
Fortunately, although it is very common in natural settings, C.
cavifrons only rarely infests homes or buildings. Only a few
instances have been reported of C. cavifrons in structures.
Authors:
Angela S. Brammer and
Rudolf H.
Scheffrahn, University of Florida
Photographs: Angela S. Brammer and Rudolf H. Scheffrahn, University of
Florida
Project Coordinator:
Thomas R. Fasulo, University of Florida
Publication Number: EENY-289
Publication Date: December 2002.
Copyright 2002 University of Florida
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