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Necrobia rufipes (De Geer, 1775)

Synonym(s) : 

Common names

  • Nécrobie à pattes rouges
  • Copra beetle copra red-legged ham beetle
  • Gorgojo de la copra Escabaro del tocino
  • Schinkenkäfer Koprakäfer Rotbeiniger

Classification:

  • Order:  Coleoptera
  • Family:  Blattelidae
  • Genus:  Necrobia
  • Species:  rufipes

Frequency index:

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Overview

Most insects of the Cleridae family are predators of various species of necrophagous insects, but Necrobia rufipes are the exception to the rule: they feed on various substrates of animal as well as of plant origin, and they are also necrophagous and even cannibal. T
hey are also the only truly harmful species among those of the Cleridae family, and in tropical regions, they are above all a true scourge for copra kept in warehouses and for dried fish.

In museums, they can severely damage insect collections. They are common in natural environments, especially in southern regions, where they feed on animal debris or remains (insects, small mammals…).
They are good fliers and they are attracted to ultra-violet light. They often go together with infestations by insects of the Dermestidae family as they have similar habitats, and moreover they readily feed on Dermestidae’s eggs and larvae.

Necrobia rufipes look very much like their related species Necrobia ruficollis (Fabricius, 1775), but in N. ruficollis the upper part of the thorax is thoroughly of a rusty colour, together with the elytron base.

They also look very much like Necrobia violacea (Linnaeus, 1758), which are the same colour as N. rufipes on their back, but can be told from them thanks to their completely black legs.

Recognition criteria

Adult

Size

3.5 to 7 mm long


Aspect

Elongate body, elytra 2.5-fold more in length than in width.
Rather short, 11-articled antennae, ending in a strong club composed of 3 articles.
Elytra punctuated with 10 longitudinal rows of dark spots and covered in stiff dark bristles also visible on the sides of the thorax.  


Colour

Metallic blue glint on the whole body (upper and lower parts, but slightly darker on the lower part), turning purplish or greenish in some cases.
Orange-coloured legs, blackish antennal club.

 

Larva

Size

10 mm long and about 2 mm wide at the final growth stages


Aspect

Legs and head quite visible. Body covered in erect red bristles.
Two horny swellings pointed upward on the last abdominal segment


Colour

Creamy white, with pink to purplish spots on the top. Head and first thoracic segment highly slerotized and shiny black on their upper part, along with the last abdominal segment (pygidium).

 

Development cycle

It lasts between 42 and more than 100 days, depending on the origin (animal or plant) of the substrate the eggs were laid on. Females can lay up to 1,500 eggs on a food base of animal origin, but far less (50) on a plant substrate.

Eggs are laid in cracks in the substrate and as soon as they hatch, larvae bore deep galleries where they feed on fragments of plant or animal food, and on coleoptera or even diptera eggs and larvae. 

In the course of their development, larvae undergo 4 molts. There are several larval stages. At the last stage, larvae build a cocoon inside the substrate or in a dark cavity outside the substrate where nymphosis takes place. Imagos can live 14 months at most in optimal conditions, which depend on their environment and on ambient hygrometry.
The optimal temperature for new-born larva development is around 30°C, with a minimum of 22°C and a relative humidity rate of 50%.
That insect’s population can grow rapidly (X25) each month in optimal development conditions.

Infected materials

The food diet of copra beetles is necrophagous and can even be cannibal.
They also feed on plant products, especially when they are rancid. Infested foodstuffs are dried fruit, peanuts, copra, cocoa, spices, meat and fish (especially when dried), and some dairy products, including cheese. Necrobia rufipes are occasional predators and can also devastate insect collections.

Geographical distribution

Worldwide distribution, especially in the hot, damp regions of the globe.