Apple blossom weevil

Identification

A small beetle of the weevil family, about 4–5 mm long, brown-grey, with a pale, oblique V-shaped band on the wing cases and a long, curved snout. In early spring, before flowering, the females lay single eggs inside the developing flower buds; the hatched legless larva eats out the inside of the bud, which stops developing, turns brown and dries up, remaining closed as if "scorched" — this is the most conspicuous symptom. It feeds on apple and pear; under heavy pressure it can destroy a considerable part of the flower buds. The main and proper host is the apple — on pear, comparable bud damage is caused above all by other, closely related blossom-weevil species (among them the pear blossom weevil, Anthonomus piri), so infestation of pears can only occasionally be attributed to this species. The species produces one generation per year. The adult beetles overwinter in bark crevices, under lifting flakes of bark, in leaf litter and at the base of the trunks; in early spring, once the temperature rises above a few degrees (roughly at the bud-swelling and green-bud stage), they leave their hiding places and move up into the crowns. As they feed, they pierce the swelling buds with their snout, and droplets of sap flow out — a symptom known as "bud weeping." The female bores a hole in a flower bud with its snout and lays a single egg inside it. The larva develops in concealment, eating out the stamens and pistil, then pupates inside the browned, undeveloped bud — the dried petals form a characteristic brown "cap" over it. The young beetles of the new generation emerge at the turn of spring and summer, feed briefly on the leaves, and then withdraw to their shelters for summer dormancy and overwintering. The harmfulness depends strongly on the abundance of flowering: in years of lush flowering, the destruction of some buds acts like natural thinning and may be immaterial to the yield, whereas with weak flowering the loss of fruit set is severe.

Treatment

Early-spring beating of the beetles from the branches onto spread sheets on cool mornings, when the insects are torpid, followed by destroying them is effective — the operation is repeated during bud swelling. Collecting and destroying infested buds helps. In orchards, beneficial fauna is encouraged, and chemical control is used only exceptionally, only when the damage threshold is exceeded and before flowering, so as to protect pollinators. The basis for deciding on a treatment is monitoring: beating the twigs over a sheet or an entomological umbrella at the bud-burst stage allows the number of beetles to be assessed and compared with the damage threshold — only exceeding it justifies spraying. Natural enemies keep the population down: larvae hidden in the buds are sometimes parasitised by small wasps, while overwintering beetles and those feeding in spring are eaten by insectivorous birds, especially tits — it is worth supporting them with nest boxes and caring for the orchard's biodiversity. Winter reduction of shelters also helps: removing lifting bark and tidying up the litter at the base of the trees. If chemical intervention proves necessary, it is carried out with a contact insecticide (e.g. from the pyrethroid group) at the green-bud stage, still before flowering — the target is the adult beetles before egg-laying, because once the larva has closed itself inside the bud no product will reach it. Treatments are never carried out during flowering, in order to protect bees and other pollinators.

How to tell it apart from look-alikes

Control — organic and chemical methods

We give active-ingredient groups and modes of action, not brand names — specific products and their approval vary by country and are sometimes withdrawn. Always check and follow the current label.