Tree pests are among the biggest threats to Czech forests – the European spruce bark beetle, the nun moth or the green oak tortrix can turn a healthy forest into a devastated clearing within a single season. Knowing these species, being able to recognise the signs of an infestation and understanding their ecology is the first step towards protecting our forests and the precious wood from which the products we use every day are made.
🪲 Test yourself: can you recognise tree pests?
Our interactive quiz takes you into the world of forest pests – from bark beetles and caterpillars to cockchafers. Choose a difficulty level and find out how well you know the threats hidden under the bark of Czech trees.
🌳 Looking for a gift made of natural wood? At AMADEA you will find handmade products from Czech forests – from decorations to kitchen accessories.
Visit AMADEAA guide to the most dangerous tree pests in Czechia
Czech foresters deal with dozens of pest species; some cause only local damage, while others can trigger real outbreaks. Below we present the six most important species that every lover of nature and wood should know.
European spruce bark beetle – Ips typographus
The European spruce bark beetle is without doubt the most feared pest of Czech forests. This tiny beetle (4.2–5.5 mm long) lives under the bark of spruces and attacks mainly trees weakened by drought, wind or age. Adults usually swarm in April and May, when temperatures rise above 16–18 °C, and find suitable hosts with the help of attractant pheromones.
Under the bark, the beetles excavate a characteristic gallery system – the females bore vertical egg galleries in which they lay 40–60 eggs. The larvae feed on the inner bark (phloem), cutting off the transport of nutrients, and the tree dies. In favourable conditions the bark beetle produces 2–3 generations a year. In the Šumava and the Jeseníky, after 2017 it caused an outbreak affecting vast areas of spruce monocultures.
Spruce wood is a popular material in Czechia for making kitchen accessories and decorative objects – a reminder of how precious every living tree in the forest is.
Nun moth – Lymantria monacha
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The nun moth is a night-flying moth whose caterpillars devour the needles of spruces, pines, firs and larches en masse. During population outbreaks they can completely defoliate stands over thousands of hectares. Females lay their eggs in August and September in cracks in the bark, where they overwinter. In spring tiny caterpillars hatch and let themselves be carried by the wind on silk threads ("ballooning"), spreading over long distances.
The caterpillars are easy to recognise – they are grey-black, very hairy and patterned. Czech forests last saw a major nun moth outbreak in the 1990s, and locally after 2000 in the Elbe lowlands and Central Bohemia. Today populations are monitored with pheromone traps and aerial surveys.
Forest cockchafer – Melolontha hippocastani
While the adult cockchafer nibbles the leaves of oaks and other broadleaved trees, the real damage is done by its grubs – fat, white larvae that live in the soil. The grubs feed on the roots of saplings and seedlings, destroying entire plantings. The life cycle takes 3–4 years: adults appear in large numbers every four years in a characteristic "cockchafer year" (the timing varies by region).
In Czechia the forest cockchafer is widespread mainly in sandy lowland and hilly areas, where it prefers open broadleaved and mixed forests. A forestry problem arises in nurseries and young plantations, where grubs can destroy entire areas of seedlings.
Green oak tortrix – Tortrix viridana
The green oak tortrix is an inconspicuous green moth with a wingspan of about 18–22 mm, whose caterpillars cause massive defoliation of oaks. The caterpillars hatch in sync with bud burst in spring – a biological timing that requires precise coordination with weather conditions. In unusual temperature years there can be a phenological mismatch, with the caterpillars hatching too early or too late.
A healthy oak usually survives an outbreak thanks to a second flush of leaves (the so-called "Lammas growth") in July. Repeated defoliation combined with other stresses (drought, fungi), however, can weaken the tree so much that it is attacked by secondary pests such as Agrilus biguttatus – the two-spotted oak buprestid. Oak is also a popular material for kitchen boards and serving platters – its wood is exceptionally strong and durable.
Two-spotted oak buprestid – Agrilus biguttatus
The two-spotted oak buprestid is a striking metallic green jewel beetle, a secondary pest of oaks. It attacks only trees already weakened by other stress (defoliation, drought, injury) – so its occurrence closely tracks the condition of oak stands. The larvae bore characteristic zigzag galleries under the bark that completely cut off the conducting tissues. Infested branches die back from the top down.
In Czechia the beetle is spreading mainly in warm lower altitudes (below 500 m) in the oak woods of the Elbe lowlands, Pálava and South Moravia. Climate change and repeated droughts after 2015 have caused a marked increase in its population. In places the damage is so extensive that foresters have to fell and sanitise infested stands quickly.
Six-toothed spruce bark beetle – Pityogenes chalcographus
The six-toothed spruce bark beetle is a smaller relative of the European spruce bark beetle (1.8–2.5 mm long). It attacks thinner branches and the tops of spruces, where it creates star-shaped gallery patterns with 3–8 arms. It is considered less dangerous, but during outbreaks it acts as a secondary pest and significantly speeds up the death of trees. It also helps spread blue-stain fungi, which reduce the value of the wood.
Blue-stained wood is still usable for construction, but its market price is lower. In craftwork, on the other hand, blue-stained wood is sometimes used deliberately for its decorative effect – just like wood with other natural markings, which AMADEA turns into original home decorations.
The most common mix-ups and mistakes
Telling forest pests apart from similar, harmless species is key to correct diagnosis and the right protective measures. The three most common mistakes:
The longhorn beetle has similar requirements (it attacks weakened spruces), but it is much larger (10–18 mm) and belongs to the longhorn family. Its exit holes are oval and its larval galleries go deep into the wood, while bark beetle galleries stay in the inner bark.
Both caterpillars are dark and hairy. The key difference: the spongy (gypsy) moth caterpillar has rows of blue and red dots along its back, and it mainly attacks broadleaved trees (oak, lime, birch), while the nun moth prefers conifers.
The rose chafer is also metallic green, but it is much stockier (14–20 mm) with a rounded body. Rose chafers are entirely beneficial insects – as adults they visit flowers, while their larvae live in compost and rotting wood and speed up decomposition. They never attack living trees.
Comparison table of the most important pests
| Pest | Host | Size | Damaging stage | Danger | Occurrence in Czechia |
|---|---|---|---|---|---|
| European spruce bark beetle | Spruce | 4–5.5 mm | Larva + adult | ⭐⭐⭐⭐⭐ | All of Czechia, outbreaks |
| Nun moth | Spruce, pine, fir | 35–55 mm (wingspan) | Caterpillar | ⭐⭐⭐⭐⭐ | Lower and middle altitudes |
| Forest cockchafer | Oak, beech (adult), roots (grub) | 20–30 mm | Grub (larva) | ⭐⭐⭐⭐ | Lowlands and hills |
| Green oak tortrix | Oak | 18–22 mm (wingspan) | Caterpillar | ⭐⭐⭐ | Warm lower altitudes |
| Two-spotted oak buprestid | Oak (weakened) | 8–13 mm | Larva | ⭐⭐⭐⭐ | Elbe lowlands, South Moravia |
| Six-toothed spruce bark beetle | Spruce (branches, tops) | 1.8–2.5 mm | Larva + adult | ⭐⭐⭐ | All of Czechia |
Frequently asked questions about tree pests
How can I tell if a tree is infested with bark beetles?
On the bark of an infested spruce you can see small round holes 1–2 mm across, from which fine brown dust trickles out. The bark peels off, revealing the characteristic gallery patterns underneath. The needles turn yellow and fall – usually starting at the lowest branches.
What is a bark beetle outbreak and why is it so serious?
A bark beetle outbreak occurs when the population of the European spruce bark beetle multiplies uncontrollably and destroys large areas of spruce forest. In Czechia the largest outbreak hit after 2017, when a series of dry years weakened the trees. Dead standing trees must be processed quickly, otherwise they become a source of further spread.
Are all insect pests equally dangerous?
No. Some pests, such as the European spruce bark beetle or the nun moth, can kill entire stands when their numbers explode. Others, such as the green oak tortrix, cause defoliation, but a healthy tree usually recovers. The level of danger depends on the tree species, the condition of the tree, repeated attacks and the climatic conditions of the year.
How are tree pests controlled naturally?
Natural enemies of pests include woodpeckers (they look for larvae under the bark), cuckoos (caterpillars), ants, parasitoids (ichneumon wasps and braconids lay their eggs in caterpillars) and predatory beetles. Healthy, species-rich mixed forests are much more resistant to pest outbreaks than spruce monocultures.
Can an ordinary person help protect forests from pests?
Yes. Report heavily infested trees to foresters. Support the planting of mixed forests instead of monocultures. Do not take freshly cut wood with bark from infested areas to other places. And when you buy wooden products, choose ones like those from AMADEA, made from Czech wood whose processing supports sustainable forest management.
Where can I find products made of Czech wood as a reminder of the beauty of the forest?
At AMADEA we make handcrafted products from native woods – spruce, oak, alder, beech and others. You will find home decorations, kitchen boards and gifts that celebrate the beauty and value of the Czech forest. Every product tells the story of wood that has passed through the hands of skilled craftspeople.
🌳 Looking for a gift made of natural wood? At AMADEA you will find handmade products from Czech forests – from decorations to kitchen accessories.
Visit AMADEAAuthor: Martin Portych – specialist in wooden products, gift advice and shop content
Editorial policy: Our content is based on the day-to-day practice of the AMADEA shop, the real needs of our customers and a commitment to clear, useful and trustworthy information.