Lyctus linearis (Goeze, 1777)


Synonym(s) : 

Common names

  • Lycte ligné
  • European Lyctus beetle
  • Carocoma des parquets
  • Parkettekäfer


  • Order:  Coleoptera
  • Family:  Bostrichidae
  • Genus:  Lyctus
  • Species:  linearis

Frequency index:

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Although they are not as frequent as their related species Lyctus brunneus (cf. fact-sheet), Lyctus linearis are also xylophagous insects to be dreaded. Let us note that the 2 species can easily be mistaken. Lyctus linearis are frequent in natural environments, but can also be found in warehouses, museums, housings… where, like L. brunneus, they infest old furniture, floorings and all sorts of worked woods (picture frames, various objects…). They preferentially develop in dry or very dry wood. Their larvae are infested by various parasitoid (Braconidae Hymenoptera) and predaceous insects (Cleridae Coleoptera), but they are not in high enough numbers to ensure efficient biological control of that pest.

Recognition criteria



4 to 6.5 mm long.


Elongate insects, with parallel sides, slightly flat, quite visible wide head with powerful mandibles.
Eleven-articled antennae, antennal clubs formed of 2 articles; antennae slightly longer than the thorax. Sides of the thorax more or less parallel and finely crenulated (scalloped), with a long dimple in its middle. Elytra about 2.3-fold more in length than in width. They have parallel rows of quite visible dots, the pubescence is also in rows, and made of golden flat bristles pointing toward the rear end.


Entirely yellowish brown to red brown.




4 mm to 8.5 mm long at their final development stages


Look like small, curved white grubs. Short legs, fore legs more developed than the others. Body covered in a short golden-coloured pubescence. Hind abdominal stigma quite developed. Let us note that Lyctus linearis and L. brunneus larvae look very much the same.


Entirely greyish white body, but for the head which is partly reddish

Development cycle

Lyctus linearis and L. brunneus have nearly the same development cycle altogether.
It ranges between 80 and 300 days (up to 2 years) depending on ambient conditions and on the nutrient value of the food substrate.
Adults come out as soon as April and are active at dusk. Females lay their eggs in small cracks in wood vessels (more than 0.05 mm in diameter), provided that they are dry, intact and have a very high starch content. Average fecundity is about 20 eggs, laid separately (they are laid in small bunches of 2 to 6 by L. brunneus). The eggs are translucent and round, 1 mm  in diameter, but they are very soft, which allows their insertion into cavities smaller than their actual diameter. They incubate for 1 or 2 weeks (depending on ambient thermo-hygrometric factors). Larval development is variable, as larvae remain inactive in winter and when ambient conditions are not favourable. New-born larvae live in 1- to 3-mm wide galleries that they bore along the wood grain, which differentiates them from furniture and deathwatch beetles (cf. Anobium punctatum and Xestobium rufovillosum fact-sheets, for example), whose galleries are bored in all directions.
Galleries are often blocked by bore-dust with a very fine and very volatile aspect (“meal flower” aspect). Bore-dust can sometimes be seen on the outside, which is a good indicator of that dreadful pest’s presence. Once their development is over, larvae turn into nymphs and the nymphal stage lasts between 2 and 3 weeks.
When adults are formed, they settle in small cells quite close to the surface where they stay for about 4 days, and then they bore a hole to the outside to break free and take flight. It should be noted that Lyctus linearis exit holes are round, like those of furniture and deathwatch beetles.
Adults’ emergence occurs between April and September, there can be 2 or 3 generations per year in heated places, at temperatures ranging between 17 and 23°C, and humidity rates between 40 and 60% outside the wood and 14% inside the wood (below 7% humidity rate, larvae cannot develop).
Male adults live about 2 months, females about 4 months.

Infected materials

Lyctus  linearis more particularly infest floorings, wood panelling, plinths, door or window frames, furniture and all kinds of worked woods or wooden objects through which their larvae bore countless galleries that weaken the wood and sometimes cause it to actually crumble down.
When their flight holes are spotted on the surface, it is usually too late to do anything, for the infested material is then often full of galleries.
They are particularly fond of the soft parts (sapwood) of deciduous trees such as oak, chestnut-tree, ash, walnut-tree, elm, willow, cherry-tree, but more rarely beech or poplar.
Starch-rich tropical woods (abachi, koto, okoumé, limba, lomba, ramin, along with bamboo, acacia, mahogany…) are destroyed by European lyctus beetles, as well as plywood, which is often made from the woods cited above.
It is important to note that wood from resiniferous trees is never infested by Lyctus linearis (but it can be infested by other insects (cf. Hylotrupes bajulus fact-sheet, for example)).

Geographical distribution

Lyctus linearis originally came from tropical regions, but they are now distributed worldwide due to the flourishing international wood trade. They are even found in countries known for their cold climate, such as Finland or Sweden.