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Carpet Beetles
DESCRIPTION
Order: Coleoptera (‘sheath-wings’)
Characteristics:
Forewings hard and leathery, meeting along mid-line of dorsal surface:
hindwings membranous, sometimes lacking; biting mouthparts; well-developed
thorax; complete metamorphosis with egg, larval, pupal and adult stages.
Family: Dermestidae (skin feeders)
Species characteristics:
Varied Carpet Beetle (Anthrenus verbasci)
Adults, 2-4mm long, body strongly convex; colour: variable, brown or black
and mottled with yellow or white scales on the dorsal surface; ventral
surface clothed with fine grey-yellow scales; 11-segmented antennae with
3- segmented clubs at tip, clubs have nearly parallel sides; at rest,
antennae lie in recesses in thorax; eyes smoothly rounded; legs short,
retracting into grooves on the ventral surface; larvae brown, bearing
3 bunches of golden hairs on tip of abdomen.
Furniture Carpet Beetle (Anthrenus flavipes (formerly vorax))
Adult, 2-4mm long, body strongly convex; colour: variable, brown or black
and mottled with yellow or white scales on the dorsal surface; ventral
surface clothed with white scales; 11-segmented antennae with 3- segmented
oval clubs at tip; at rest, antennae lie in recesses in thorax; eyes indented
on inner side; legs short, retracting into grooves on ventral surface;
legs thickly clothed with yellow scales; larvae brown, bearing 3 bunches
of golden hairs on tip of abdomen.
Museum Beetle (Anthrenus museorum)
Adult, 2-2.8mm long, body strongly convex; colour: variable, brown or
black and mottled with yellow or white scales on the dorsal surface; antennae
are 8-segmented, with 2- segmented clubs; at rest antennae lie in recesses
in thorax; legs short, retracting into grooves on the ventral surface;
larvae brown, bearing 3 bunches of golden hairs on tip of abdomen.
Fur Beetle (Attagenus pellio)
Adults, oblong shape and 4.5-6mm long; colour: black, but for small patch
of white hairs on either side of elytra; base of thorax also covered with
white hairs; larvae have distinctive tuft of very long hairs which project
backwards.
DISTRIBUTION
The Varied carpet beetle is indigenous to Europe and in England is common
south of a line drawn between Bristol and the Wash. The Furniture carpet
beetle is of subtropical origin and more cold sensitive.
Both species are pests of animal products and occasionally food products
of plant origin. Consequently, they may be found wherever these commodities
are stored or handled. Carpet beetles are now one of the major pests of
textiles, their success being attributed to central heating, which ensures
uniform temperatures, and to the increasing use of wall-to- wall carpeting,
which allows the insects to breed undisturbed. Furthermore, the success
of industrial mothproofing treatments has effectively removed the moth
challenge.
Warm, dry conditions are ideal for their development, but they can survive
in foodstuffs of very low moisture content, e.g. 11-12%.
As its common name suggests the Museum beetle is commonly encountered
in museums where it is a particular pest of dried specimens. It will also
attack textiles and has been recorded as infesting grain. The Fur beetle
may be found in a wide variety of products including furs, skins, textiles
and grain.
Adult carpet beetles live outdoors on pollen and nectar, taken in particular
from Umbelliferae and Spiraes. They can also be found wandering on walls
and windows. In temperate climates the larvae are particularly evident
in the autumn when they wander in search of food and hibernation sites.
Carpet beetles thrive in situations where they remain undisturbed, for
example beneath carpets, around skirting boards and in wardrobes. Bird
and rodent nests, animal remains and dead insects are frequently reservoirs
of infestations.
SIGNIFICANCE
Larval forms can cause considerable damage to keratin-containing products
such as wool, fur, leather, silk and dried animal remains. Occasionally,
food products of plant origin, such as cereals and fibres, will also be
attacked. Damage takes the form of clean, irregular holes and in textiles
these generally occur around seams. There is no webbing or excrement present
and by the time larvae are observed, considerable damage has often been
done. Because of the large number of larval moults, when cast larval skins
are seen they tend to exaggerate the extent of the infestation.
Carpet beetles are of limited significance as a health hazard, although
they are potential vectors of anthrax. In certain situations the larval
hairs cause skin irritation to those exposed to large numbers of the insects.
LIFE-CYCLES OF THE TWO MOST COMMON SPECIES
Varied Carpet Beetle
Mating occurs immediately after emergence. The females produce 20-100
cream-coloured eggs which are 0.5mm long, and have spine-like projections
at one end. Over a period of 2 weeks these are deposited in suitable crevices,
or stuck on to a potential larval feeding site by sticky secretions. In
2-4 weeks these eggs hatch to give the characteristic hairy, squat ‘woolly
bears’. When mature, these are 4-5mm long, brown in colour and possess
3 bunches of golden hairs arranged in pairs on the posterior abdominal
segments. The short legs are 5-segmented and well developed, with a single
claw on the terminal segment. The larvae avoid light and curl up into
a ball when disturbed. The length of the larval life depends upon humidity,
temperature and quality of diet. Soiled commodities are usually preferred.
During this time they generally moult at least 6 times, but the longer
they persist the more moults occur.
Pupation takes place in the last larval skin, at the site of larval development
and lasts for 10- 30 days. The adults live for 2-6 weeks, and are able
to fly to the particular flowers on which they feed and search for egg-laying
sites.
Furniture Carpet Beetle
One to three days after emergence the female lays up to 100 eggs which
are produced in 1 to 3 batches. After 3 weeks the eggs hatch, to give
larvae which vary in colour from white, through yellow, to chestnut brown,
depending upon the colour of food consumed. Their legs are short, 5-segmented
and well developed. The larvae persist for up to 12 months and are 5mm
long when fully grown.
The pupa develops inside the last skin. It is white in colour and lasts
for 2-3 weeks, after which time the adults emerge.
CONTROL
The wandering habits of these insects means that they frequently infest
wide areas, making them difficult to control.
Assessment of infestations
The first step in carpet beetle control is to trace the source of infestation.
This may be an old nest, animal remains, wool-based lagging, sound-proofing,
wool-based furnishings or the debris that accumulates between and around
floorboards.
a) Hygiene/management
All sources of infestation should be removed and burnt if possible. Routine
surveillance and regular cleaning are also important.
b) Insecticidal control
Thorough surface spray treatments with residual activity are vital where
infestations are extensive in order to ensure that all larvae are killed.
Care should be taken when treating carpets and other valuable furnishings.
Glossary of terms
Elytra: Hardened forewings of the beetle.
ADVICE
Valent BioSciences has an extensive range of products specifically formulated
for the control of flying and crawling insect pests.
Further information on all Valent BioSciences' household insecticide products
is available from:
Valent BioSciences Corporation
870 Technology Way
Suite 100
Libertyville, IL 60048
The greatest care has been taken to ensure the accuracy of the information
contained in this Fact Sheet. Under no circumstance, however, will Valent
BioSciences Corporation be liable in respect of any error or omission.
© Copyright Valent BioSciences Corporation 2001
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