Predation of overwintering larvae of codling moth (Cydia pomonella (L.)) by birds.
In investigations in cider-apple orchards in southern England in winter 1971-73, groups of up to 30 larvae of Cydia pomonella (L.) were allowed to spin cocoons under the bark of apple logs which were then tied into trees. Some logs were caged in wire netting to exclude birds. The losses of larvae from exposed logs were 94.7, 94.9 and 95.6%, respectively, in the 3 winters, as compared with few or no losses from caged logs. Most larvae disappeared in the first few weeks, and losses were higher from logs bearing 14-30 larvae than from those with 7 or fewer. The only bark-hunting birds seen in the orchards were blue tits (Parus caeruleus) and great tits (P. major). They were seen working the bark, and left identifiable marks and holes there, and the remains of cocoons.