Bagrada hilaris
In 3 days ~10% in a week ~20%
Bagrada hilaris is a species of shield bug known by the common names bagrada bug and painted bug. It could be mistaken for or erroneously referred to as harlequin bug. It is native to southeastern Africa. It is known elsewhere as an introduced species, including California and Arizona, where it was first reported in 2008. It is a major pest insect of Brassica oleracea crops (including cabbage, kale, cauliflower, Brussels sprouts, and broccoli), and related crucifers such as turnips, rape, and mustard. The adult and nymph of the species suck sap from the leaves of the plants, causing wilting, yellowing, and stunting of growth. Besides crucifers, the bugs are known on papaya, sorghum, maize, potato, cotton, caper, pearl millet, and some legumes. Large numbers of the bug congregate on the plants and cause extensive damage.
The adult bug is 5 to 7 millimeters in length, shield-shaped, and black with white and orange markings. The female, which is larger than the male, lays up to 100 oval or barrel-shaped eggs on leaves or in soil beneath plants. The eggs are white when freshly deposited and turn orange over time. Within 8 days the first-instar nymph emerges. It is bright orange-red and turns darker as it develops, becoming black by the last instar.
The bug made a sudden appearance in Los Angeles in June, 2008, its first sighting in the Western Hemisphere. It then moved into the cropland of the heavily agricultural Coachella and Imperial Valleys of California, doing damage to cole crops there, especially those grown organically. By September 2014 it had reached as far north as San Mateo, Santa Cruz, Merced and Inyo counties, and all California counties to the south except Tulare County. As of 2020, it was found as far north as Yolo County.
Past infestations have been reported in India. It was found for the first time in Chile in 2016, where it rapidly established and began generating economic loss as well as invading homes in several Chilean localities. A 2019 study found the eggs of invasive B. hilaris in Mexico being parasitized by a new species of parasitoid wasp, Idris elba (named after the actor of the same name). I. elba has thus been identified as a potential control agent for B. hilaris, which may benefit the broccoli crops that B. hilaris infests. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Channel Islands National Park | 🇺🇸 United States | |
| 2 | Garden Route National Park | 🇿🇦 South Africa | |
| 3 | Cumbres de Monterrey National Park | 🇲🇽 Mexico | |
| 4 | Table Mountain National Park | 🇿🇦 South Africa |
Rare
Under 5% of wildlife watchers report a Bagrada Bug sighting in San Francisco on a given day, based on 114 verified sightings from GBIF citizen-science data. It is the 162nd most-seen of the 737 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.
July and August
In those months about 10% of wildlife watchers report a Bagrada Bug in San Francisco on a given day, against under 5% in September to June, the lowest months. Those are among San Francisco's driest months, with almost no rain against 110 mm in December.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Bagrada Bug sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
15th of 17
Of the 17 cities where we can rate Bagrada Bug sightings, San Francisco ranks 15th at under 5%. The best odds are in Kanpur (India, about 20%), Santiago (Chile, about 10%) and Prayagraj (India, about 10%).
GBIF citizen-science records
It is estimated from how often the Bagrada Bug is recorded against all the insects logged in San Francisco (114 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.
