Small beetles

Small-sized beetles

1. Identification

• Common name: Various (See individual species sheets)
• Scientific name: Various species from several families of Coleoptera (see point 3)
• Main families: Nitidulidae, Curculionidae, Chrysomelidae, Bostrichidae, Scolytinae, Buprestidae, Scarabaeidae
• Order: Coleoptera

2. General description

• Insects of reduced dimensions, generally smaller than 1 cm.
• Active adults, with great mobility and dispersal capacity.
• Larvae may be phytophagous, leaf-mining, boring or feed on superficial tissues.
• Many species act as secondary pests, but may cause significant damage under favourable conditions.

3. Main hosts

• Agrilus spp. – Various broadleaf and fruit trees; wood-mining larvae.
• Agriotes spp. – Various crops; larvae (wireworms) attack roots and tubers.
• Altica ampelophaga Guérin‑Méneville – Grapevine.
• Aphanisticus emarginatus Olivier – Grapevine (larvae mining the canes).
• Byturus spp. – Small fruits, especially raspberry and blackberry.
• Carpophilus freemani Dobson – Overripe fruits, citrus, fig, vine and stone fruits.
• Carpophilus hemipterus L. – Ripe or damaged fruits of citrus, fig, vine and various fruit trees.
• Carpophilus mutilatus Erichson – Decomposing fruits, citrus, fig, vine and small fruits.
• Cneorhinus serranoi Germain – Various ornamentals and fruit trees.
• Cosmopolites sordidus Germar – Banana.
• Crioceris asparagi Linnaeus – Asparagus.
• Crioceris duodecimpunctata L. – Asparagus.
• Exomala (=Anomala) orientalis Waterhouse – Various crops; rhizophagous larvae.
• Halyomorpha halys Stål – Polyphagous; fruit trees, vegetables and ornamentals.
• Hylastinus obscurus Marsham – Clover and forage legumes.
• Hypothenemus eruditus Westwood – Various woody species, especially weakened wood.
• Hypothenemus hampei Ferrari – Coffee plant.
• Ips acuminatus Gyllenhal – Pine.
• Ips cembrae Heer – Larch and other conifers.
• Ips sexdentatus Boisduval – Pinus spp.
• Ips typographus L. – Picea spp.
• Oulema melanopus L. – Cereals, especially wheat and barley.
• Phyllotreta spp. – Brassicaceae (cabbage, turnip, radish).
• Pityophthorus juglandis Blackman – Walnut.
• Platypus cylindrus Fabricius – Oak and other broadleaf trees; borer of weakened trunks.
• Popillia japonica Newman – Various crops; polyphagous adults; rhizophagous larvae in lawns and meadows.
• Pyrrhalta (=Xanthogaleruca) luteola Mülle) – Elm.
• Scolytus amygdali Gerstäcker – Almond and other Prunoideae.
• Scolytus multistriatus Marsham – Elms.
• Sitophilus granarius L. – Wheat and other stored cereals.
• Sitophilus oryzae L. – Rice, maize and stored cereals.
• Xyleborus dispar Fabricius – Pomoideae and other broadleaf trees (chestnut); trunk borer.

4. Symptoms and damage

• Superficial borings in fruits, leaves or stems.
• Damage to ripe or wounded fruits, favouring secondary rots.
• Borings in stored seeds or grains, with losses in weight and quality.
• Mines in leaves or stems, causing necrosis and reduction of the photosynthetic area.
• Decline of young plants in attacks to the collar or roots.

5. Biological cycle

• Cycles generally short, with several annual generations or 1 single annual generation (variable depending on the species).
• Development favoured by high temperatures and high food availability.
• Adults seek ripe fruits, tender tissues or stored material for egg-laying.
• Larvae develop inside the food, protected from external factors.

6. Monitoring

• Visual inspection of ripe fruits, leaves and stems.
• Observation of borings, superficial galleries or mines.
• Food or pheromone traps for species such as Carpophilus spp.
• Regular monitoring of warehouses and silos for early detection of infestation.

7. Management measures

• Cultural: They include practices that reduce the availability of food and breeding sites. The removal of fallen or damaged fruits, timely harvesting and the elimination of plant residues decrease the attractiveness for species such as Carpophilus spp. Keeping warehouses clean, dry and well ventilated reduces the risk of infestation by beetles of stored products. In field crops, crop rotation, the elimination of weeds and the maintenance of plant vigour help to reduce susceptibility.
• Biological: They are based on the action of natural enemies present in the agroecosystem, including egg and larval parasitoids, generalist predators and entomopathogens such as Beauveria bassiana and Metarhizium anisopliae, effective on several small-sized species. In warehouses, the use of beneficial insects specific to the biological control of grain pests can be integrated into management programmes. The preservation of these agents requires avoiding broad-spectrum insecticides and maintaining conditions favourable to their activity.
• Integrated protection: They rely on regular monitoring and selective intervention. The use of food or pheromone traps allows the detection and reduction of populations of Carpophilus spp. and other species. Treatments should be directed at the periods of greatest adult activity, using selective substances compatible with the auxiliary fauna. In warehouses, the application of good hygiene practices, adequate ventilation and humidity control are fundamental. The integration of cultural and biological measures and continuous monitoring makes it possible to keep populations below the damage threshold.

Bibliographic references

• EPPO Global Database – Carpophilus spp., Hypothenemus spp., Sitophilus spp., Altica spp., Scolytus spp., Ips spp., Xyleborus dispar, Agrilus spp.
• CABI Invasive Species Compendium – Various species of small-sized beetles.
• EFSA Panel on Plant Health – Pest categorisation reports for Popillia japonica, Ips typographus, Ips sexdentatus, Xyleborus dispar, Pityophthorus juglandis (2017–2023).
• USDA Forest Service – Forest Insect & Disease Leaflets (Scolytinae and Buprestidae) (editions 2015–2022).
• Rees, D. (2004). Insects of Stored Products.
• Vega, F.E. et al. (2009). The coffee berry borer: biology and control.
• Potter, D.A. (1998). Japanese beetle biology and management.
• Haack, R.A. (2006). Global spread of wood‑boring beetles via international trade.
• Jolivet, P. (1988). Biology of Chrysomelidae.
• Wood, S.L. & Bright, D.E. (1992). A Catalog of Scolytidae and Platypodidae.