Do you fancy a challenge leading up to Christmas? Can you help us put more dots on the map and biological records in the database by taking a closer look at Holly plants when you are out and about? Phytomyza ilicis is a small species of fly (~3mm) that lays its eggs in Holly leaves. The larva develop in the leaf and leave tell tale signs that are easy to spot. As Holly leaves are very tough the female fly lays eggs in leaves in April-May when they are new and soft. The larva initially tunnels along the midrib and later feeds on the leaf blade where it produces a distinctive blotch that is easy to see with the naked eye. Even though the larvae are only 1.5mm they are still susceptible to parasitic wasps and predation by birds, particularly Blue Tits.