Phytomyza ilicis
In 3 days ~10% in a week ~30%
Phytomyza ilicis, the holly leaf miner, is a leaf mining fly in the family Agromyzidae, whose larvae burrow into leaves of the holly tree (Ilex aquifolium) leaving characteristic pale trails or leaf mines. Adults of P. ilicis are small with a wing length measuring 2.5–3 millimetres (0.098–0.118 in). They have red eyes and 6–8 pairs of acrostichal bristles on the thorax.
Larvae are pale, leg-less maggots lacking a head capsule and thoracic and abdominal legs like most fly larvae. The dark-brown coloured puparium is formed from the hardened last larval skin. The holly leaf miner is found throughout the holarctic on its host Ilex aquifolium. It is common and widespread in Europe and has been introduced into western Canada and north west USA. Its distribution is probably dependent upon average temperatures; Peterkin and Lloyd found it absent from areas where the mean temperatures of the coldest months of the year falls below −0.5 °C (31.1 °F).
Female Agromyzidae insert an egg in the leaf tissue using an ovipositor. In the case of P. ilicis this poses a problem, because the leaf of the hostplant is unusually tough. Only during the annual... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 2 | Wadden Sea National Park | 🇩🇪 Germany | |
| 3 | Great Bear Rainforest | 🇨🇦 Canada |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Liverpool | 🇬🇧 United Kingdom | |
| 2 | Birmingham | 🇬🇧 United Kingdom | |
| 3 | London | 🇬🇧 United Kingdom | |
| 4 | Manchester | 🇬🇧 United Kingdom | |
| 5 | Vancouver | 🇨🇦 Canada | |
| 6 | Berlin | 🇩🇪 Germany | |
| 7 | Brussels | 🇧🇪 Belgium | |
| 8 | Leeds | 🇬🇧 United Kingdom | |
| 9 | Dublin | 🇮🇪 Ireland | |
| 10 | Rotterdam [The Hague] | 🇳🇱 Netherlands |
Rare
Under 5% of wildlife watchers report a European Holly Leafminer sighting in Great Bear Rainforest on a given day, based on 7 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 159th most-seen of the 235 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
March and April
In those months about 20% of wildlife watchers report a European Holly Leafminer in Great Bear Rainforest on a given day, against under 5% in May to February, the lowest months.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most European Holly Leafminer sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
3rd of 3
Of the 3 parks where we can rate European Holly Leafminer sightings, Great Bear Rainforest ranks 3rd at under 5%. The best odds are in Snowdonia National Park (United Kingdom, about 10%) and Wadden Sea National Park (Germany, about 10%).
GBIF citizen-science records
It is estimated from how often the European Holly Leafminer is recorded against all the insects logged in Great Bear Rainforest (7 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
