Psyllopsis fraxini
In 3 days ~10% in a week ~20%
Psyllopsis fraxini is a psyllid which lives within a gall on ash (Fraxinus excelsior). Eggs are laid in the autumn on dormant buds and the nymphs hatch in the spring and feed on the leaves. The host plant reacts by producing extra cells and the affected areas become swollen and rolls downwards and encloses the wax covered nymphs. Each gall may contain two or three generations and by the end of summer contain all stages of the insect. The galls are pale-coloured with violet or red markings. Wikipedia →
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Rare
Under 5% of wildlife watchers report an Ash Psyllid sighting in London on a given day, based on 24 verified sightings from GBIF citizen-science data. It is the 688th most-seen of the 1504 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
June and September–October
In those months about 10% of wildlife watchers report an Ash Psyllid in London on a given day, against under 5% in July–August and November–May, the lowest months.
2nd of 3
Of the 3 cities where we can rate Ash Psyllid sightings, London ranks 2nd at under 5%. The best odds are in Liverpool (United Kingdom, about 10%).
Same order: Hemiptera
The closest relatives of the Ash Psyllid that you can see in London (order Hemiptera, True Bugs, Hoppers, Aphids, and allies) are Green Shield Bug (about 30%), Trivial Plant Bug (about 30%) and Dock Bug (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Ash Psyllid is recorded against all the insects logged in London (24 verified sightings), 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.
