Portevinia maculata is one such species. Its larvae live in the bulbs of Allium ursinum (Ramsons or Wild Garlic) where they exist from late May through to early April. Adults emerge after a brief spell as a puparium and males (see photo) can be very abundant sitting on the Ramsons leaves for a short spell between late April and early June. We can therefore make use of this species biology to test the reliability of records and can also see how recording efforts have changes as people have become more interested in hoverflies.
|Portevinia maculata - male (photo by John Bridges)|
|Figure 1. Trend in frequency of records|
|Figure 2. Current distribution of Portevinia maculata (to 2017)|
|Figure 3. Phenology histogram for Portevinia maculata|