Crambus praefectellus
In 3 days ~10% in a week ~20%
Crambus praefectellus, the common grass-veneer or silver-striped webworm, is a moth of the family Crambidae described by Johann Leopold Theodor Friedrich Zincken in 1821. It is found in the United States and southern Canada east of the Rocky Mountains.
The wingspan is 18–25 mm. Adults are on wing from May to September in the north, from April to October in the mid latitudes and probably year round in southern Florida and Texas. The larvae feed on various grasses and cereal grains. Wikipedia →
| # | Park | Country | Daily sighting probability |
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Rare
Under 5% of wildlife watchers report a Common Grass-Veneer sighting in Portland on a given day, based on 17 verified sightings from GBIF citizen-science data. It is the 249th 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.
August and September
In those months about 10% of wildlife watchers report a Common Grass-Veneer in Portland on a given day, against under 5% in October to July, the lowest months. Those are among Portland's driest months, with about 40 mm of rain a month against 250 mm in December.
4th of 8
Of the 8 cities where we can rate Common Grass-Veneer sightings, Portland ranks 4th at under 5%. The best odds are in Boston (United States, about 10%), Montreal (Canada, under 5%) and Chicago (United States, under 5%).
Same family: Crambidae
The closest relatives of the Common Grass-Veneer that you can see in Portland (family Crambidae, Crambid Snout Moths) are Inornate Pyrausta Moth (about 10%), California Pyrausta Moth (about 10%) and Topiary Grass-Veneer (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Common Grass-Veneer is recorded against all the insects logged in Portland (17 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.
