Lepidosaphes ulmi
In 3 days ~10% in a week ~20%
Lepidosaphes ulmi also known as apple mussel scale or oystershell scale is a widely invasive scale insect that is a pest of trees and woody plants. The small insects attach themselves to bark and cause injury by sucking the tree's sap; this metabolic drain on the plant may kill a branch or the entire tree.
The adult female oystershell scale is up to four millimetres long, elongated, tapering to a point at the posterior end and often slightly curved, somewhat resembling a mussel shell. The upper side is a banded, brown, waxy scale and the underside is cream coloured. There are no eyes or legs and the short antennae have only a single segment. The mandibles are lengthened into a stylet adapted for sucking sap. The female lays about one hundred oval white eggs, retaining them under her body, and then dies. Her scale darkens in colour and stays in place, protecting the eggs over the winter. They can survive temperatures as low as -32 °C. They hatch in the spring at about the time the host plant's buds are bursting. The crawlers are tiny and disperse on the host, each one looking for a suitable protected site with thin bark in which to settle, remaining in that place permanently... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Portland | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report an Oystershell Scale sighting in Portland on a given day, based on 7 verified sightings from GBIF citizen-science data. It is the 427th most-seen of the 507 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.
Any time of year
In every month with enough records, under 5% of wildlife watchers report an Oystershell Scale in Portland on a given day, so our monthly data shows no clear season.
Only Portland, in our data
Portland is the only city on Wallace's Line with enough records to rate Oystershell Scale sightings: under 5% of wildlife watchers there report one on a given day.
Same order: Hemiptera
The closest relatives of the Oystershell Scale that you can see in Portland (order Hemiptera, True Bugs, Hoppers, Aphids, and allies) are Western Boxelder Bug (about 30%), Western Conifer Seed Bug (about 20%) and Brown Marmorated Stink Bug (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Oystershell Scale is recorded against all the insects logged in Portland (7 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.
