BRN 9-2 (uncompressed) - Flipbook - Page 3
Lac and Creosote
The early peoples of the southwestern United States used a
variety of adhesives including bitumen, asphaltum, plant
gums, and resins. The Þrst two are inorganic in nature. The
second two are organic in nature.1
Lac Scales2 are insects in the family Kerriidae (Lindinger,
1937). There are 8 species in 2 genera in this family found
within the United States and Canada. In other parts of the
world (China, India, and adjacent areas) species of Lac Scales
were used to produce shellac.
Of interest to us is the lac produced by the scale insect
Tachardiella larreae which uses Larrea tridentata (Creosote
Bush) as its primary host plant. Apparently this is the only
Lac Scale insect found in our area. Tachardiella was Þrst
described by Cockerell in 1901 (see page 112 of Early
Naturalists of the Black Range).
Here we explore the natural history of Tachardiella larreae
and the use of the lac which it produces. A survey of the
BugGuide entries for the genus (on 28 June 2025) yielded
three images, none of this species. A search of iNaturalist on
that same date was more fruitful, including an observation
by George Kinney on 20 February 2025 from a few miles
northwest of where I took the images shown in this article,
an observation by Natalie Wells on 26 March 2023 near
Radium Springs, and an observation by Andrew Potter on
14 April 2025 near Truth or Consequences.
So, what gives with the pictures of this crusty stuff on
Creosote stems. Well, that crusty stuff is the insect. The line
drawing on the following page is from Kondo and Gullan
(2010)3. Their review of the genus and their description of a
new species is worth the time if you have an interest in this
topic. The drawing was used to describe a new species (T.
argentina - not found in our area); it is a Ògeneralization of
several specimensÓ (p. 346). Compare the drawing to the
photographs shown here and two things may become
apparent. One, the need for a generalized depiction - a
drawing of one of these lumps would not necessarily be
useful. And, two, these are insects. They are complex
organisms.
Tachardiella larreae on stems of
Larrea tridentata (Creosote
Bush). South of Pony Hills (west
of CookeÕs Range). 27 June
2025.
larger within such a rigid case is not understood entirely.Ó
Louisiana State UniversityÕs ßysheet on the Lobate Lac Scale
includes images of the various life states of this species and
is generally descriptive of T. larreae.
The article by Kondo and Gullan includes a key to the
identiÞcation of species within the genus, a description of
each species, and some additional information about their
range and natural history.
The IdentiÞcation Technology Program - Scale Insects
describes the life history of Lac Scales as follows: ÒLac
scales have 3 or 4 instars in the female and 5 in the male. In
the true lac scale, Kerria lacca (Kerr) there are 2 or 3
generations each year. Eggs are laid inside a brood chamber
which is formed as the adult female shrivels during the egglaying process. There may be as many as 1,000 eggs laid by
a single female. Eggs hatch and Þrst-instar crawlers emerge
from the test through a hole near the anal opening. The
crawlers settle on the new stem growth and produce a broad
lac test. Females molt 3 times and enlarge the test until it
coalesces with the secretions of other females. Males also
produce a test, but it is narrow and has a large opercular
opening. Adult males emerge through the operculum and
may be winged or wingless. Populations may contain as
many as 30% males, but they apparently are unnecessary for
reproduction. The biology of Tachardiella larreae Comstock
has also been studied. There is 1 generation each year, Þrst
instars are laid inside the brood chamber, and appear in
early spring. Mating occurs in July and eggs begin
developing in females in late summer.Ó
At p. 348, Kondo and Gullan include a photograph of
T. argentina being tended by a species of ant (Camponotus
sp.). See pages 4 and 5 for ant species on T. larreae.
Adults of T. larreae attach to the stems of the Creosote Bush
and stay put for the rest of their lives, feeding on the plant
phloem.4 Creosote Bush generally is found at elevations
below 5,000 feet (see the survey summary at the end of this
article).
Describing a different species (the Lobate Lac Scale), the
University of Florida noted: ÒThe resinous scale covering is
light to dark reddish brown. Old individuals will frequently
appear black because of the sooty molds. The shape is
globose with four lobes, and young individuals generally
appear more lobed than mature adults. The case size is
about 1.5 mm long, and 1.0 mm wide, but individuals in
close proximity will frequently coalesce forming masses of
several individuals. Young individuals often appear like a Ôfat
bow tieÕ. The resinous case conforms approximately to the
shape of the insect inside. Exactly how the insect grows
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