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ENY 6203 Techniques for Marking Insects
Many types of ecological and behavioral studies of insects require the
marking and subsequent recognition of individuals. In some studies each
individual must be given a distinctive mark; in other studies members of
each of a few groups must be recognizable; and in still others all that is
required is that previously marked individuals be distinguishable from
These are some examples of studies employing marked insects :
* Estimates of population density by capture-release-recapture
* Studies of dispersal and migration
* Detection of the number of nymphal molts
* Determinations of longevity and mortality
* Determination of home range and territoriality
* Studies of feeding specialization by individual predators or pollinators
* Studies of dominance hierarchies, leks, and female choice
Criteria for judging marking techniques
The following criteria should be considered when selecting a marking
(1) Persistence. Will the marking last as long as required? Is it equally
permanent for all individuals? Will it survive molting?
(2) Recognition of individuals or groups. Does the technique offer
distinctive marks to discriminate as many individuals or groups as
(3) Effect of marking . Does the marking process injure the individual?
Does the marked individual have a different chance of survival than the
unmarked? Is the behavior or physiology of a marked individual
different than an unmarked one?
(4) Ease of marking . Can the necessary numbers be marked in the time
available and with reasonable expense for equipment and supplies?
(5) Ease of recognition. Can marked individuals be easily and reliably
separated from unmarked ones? Can specially marked individuals or
groups be easily and reliably distinguished from one another?
1For example, 100 butterflies per color can be marked distinctively by this system (one dot on each front wing):
(6) Transfer of mark to unmarked individuals. Can unmarked
individuals become marked by contact with marked individuals? Are the
eggs or progeny of marked individuals marked? If such transfer does
occur, can it be relied upon?
Marking techniques that have proved useful in entomological studies are
(1) notches or amputation. Notches can be made in the pronotum or
elytron and coded by position or number. Portions of a leg or an elytron
may be cut off. Both notching and amputation will sometimes last from
one instar to the next.
(2) scratches or brands. Marks, numbers, or letters can be scratched or
burned into the elytra or pronotum.
(3) paper labels. F. A. Urquhart used this system to get returns of
migrating monarch butterflies from more than 2000 km away. Adhesion
is the principle problem. The return address is the greatest advantage
over other systems.
(4) colored thread. For instance, tied between the abdomen and thorax.
(5) spots of ink, paint, or dope. Differences in shape, position, color, and
number allow coding of many individuals. Materials used include india
ink, marking pen ink, acrylic paint, nail polish, stains , dyes, oil paints,
fluorescent paints, and pigmented shellacs. These may be applied to the
wing, thorax, or elytra with pen, brush, single bristle, small wire,
pointed stick, or syringe.
(6) colored dusts. Dyes, colored chalk dust, metallic or fluorescent
powders applied by shaking the insect with the dust, brushing, or
(7) colored sprays or dips. Fluorescent paints, oil paints, aniline dyes, or
colored inks applied with sprayers or atomizers or as a dip.
(8) stained or colored food. Rearing larvae on dye-containing food may
yield colored adults. In some instances the adults lay colored eggs.
Colored food may be seen within the digestive tract of transparent
(9) radioactive materials. Applied externally as spray or dip. Applied
internally by incorporation into food or drink, by direct feeding of isotope
solution, or by injection. Radioactive wire or metal foil attached
externally or implanted. The principal advantage of radioactive
marking is that marked individuals can be detected without visual
examination (for instance in the soil or in the dark). In some cases
radioactive marking endures one or more molts and may be passed from
males to females in the sperm and from females to eggs. Other
avantages are that the marked insect is no easier for predators to detect,
the marked insect can be detected by a sensor that can activate a relay,
the tag may pass from a prey insect to its predator, and very small
insects may be easily and persistently marked. Disadvantages: Outdoor
release of radioactively marked insects is generally prohibited. Use of
radioactive materials requires costly equipment and special training and
is strictly regulated.
(10) metal discs. Glued to foraging honeybees and bearing identifying
numbers. The discs can be collected by powerful magnets as the bees
pass through chutes at the hive entrance.
(11) mutant genes. Mutant genes with easily recognized phenotypic effects
are available for some insects (e.g. Drosophila spp., Musca domestica,
Aedes aegypti); however, individuals with such genes may be abnormal
in their ecology and behavior. Genetically marked colonies have been
used to investigate mating ranges of honeybees. Here no other type
mark would work so well.
(12) natural marks. Sometimes insects from certain populations are
recognized by natural marks. For instance, butterflies of one subspecies
are at least statistically distinguishable from those of another; aphids
may be recognized as coming from a particular area by the virus they
carry; syrphids may become marked with the pollen of flowers typical of
a certain habitat or elevation. Insects from certain localities may have
characteristic allozyme frequencies or they may contain or bear certain
rare elements--see (13).
(13) rubidium and rare earth elements. When a site is treated with
compounds of unusual chemical elements, the insects in the area pick up
minute amounts that can be detected by sensitive techniques such as
atomic absorption spectroscopy or neutron activation.
Southwood, T.R. E. 1978. Methods of marking animals. Pages 70-92 in
Ecological methods with particular reference to the study of insect
populations. Chapman and Hall, London.
Walker, T.J., and S.A. Wineriter. 1981. Marking techniques for individual
recognition of insects . Fla. Entomol. 64(1): 19-29.
Wineriter, S.A., and T.J. Walker. 1984. Insect marking techniques:
durability of materials. Entomol. News 95(3): 117-123.
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