Compost Fly

Compost Fly

Ptecticus trivittatus

Daily sighting probability ~10% · With luck
at Boston

In 3 days ~20% in a week ~40%

81 Verified sightings at Boston
17 In all 2 parks From 2019 to 2026
August Best month
☀️ Diurnal When it's spotted

About the Compost Fly

Ptecticus trivittatus is a species of soldier fly in the family Stratiomyidae. Wikipedia →

Global Distribution

Parks Where Found

# Park Country Daily sighting probability
1 Shenandoah National Park 🇺🇸 United States
~10%
2 Great Smoky Mountains National Park 🇺🇸 United States
<5%

Cities Where Found

# City Country Daily sighting probability
1 Detroit 🇺🇸 United States
~10%
2 Minneapolis [Saint Paul] 🇺🇸 United States
~10%
3 Boston 🇺🇸 United States
~10%
4 Montreal 🇨🇦 Canada
~10%
5 Philadelphia 🇺🇸 United States
~10%
6 Toronto 🇨🇦 Canada
~10%
7 Baltimore 🇺🇸 United States
<5%
8 Washington 🇺🇸 United States
<5%
9 New York City 🇺🇸 United States
<5%
10 Chicago 🇺🇸 United States
<5%

Before you go

What are the chances of seeing a Compost Fly in Boston?

With luck

About 10% of wildlife watchers report a Compost Fly sighting in Boston on a given day, based on 81 verified sightings from GBIF citizen-science data. It is the 177th most-seen of the 1200 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.

When is the best time to see a Compost Fly in Boston?

June to September

In those months about 10% of wildlife watchers report a Compost Fly in Boston on a given day, against under 5% in October to May, the lowest months.

What time of day is best to see a Compost Fly?

Between 1 and 4 pm

Across all the parks we cover, that three-hour window holds the most Compost Fly sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is a daytime animal.

Is Boston the best place to see a Compost Fly?

Among the best

Of the 11 cities where we can rate Compost Fly sightings, Boston ranks 3rd at about 10%, level with the leaders once rounded. The best odds are in Detroit (United States, about 10%) and Minneapolis [Saint Paul] (United States, about 10%).

Where does the Compost Fly sighting chance come from?

GBIF citizen-science records

It is estimated from how often the Compost Fly is recorded against all the insects logged in Boston (81 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.

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