San Gabriel Valley residents are dealing with a dramatic increase in the number of black flies, a painful little insect known to bite around the eyes and neck of people and pets.
San Gabriel Valley Mosquito and Vector Control District issued a warning Residents are being advised of increased black fly activity this week in foothill communities including Altadena, Azusa, Bradbury, Duarte, Glendora, Monrovia, San Dimas and Sierra Madre. Flies develop rapidly in flowing water, where females lay 200 to 500 fertilized eggs at a time.
“Black flies are currently very active in the San Gabriel Valley, and many residents are feeling overwhelmed,” the district said in a statement. “Right now, the population is increasing due to favorable conditions, and blackflies can travel up to five miles from where they emerge, which is why they are being seen throughout the community.”
The district is treating river breeding sites to reduce the population, but has warned it could take several weeks to take effect.
In the meantime, residents are advised to take protective measures such as wearing long pants and long sleeves and using face protective gauze. According to the district, people should also consider using repellents containing DEET on exposed skin and turning off personal water features such as decorative fountains for 24 hours once a week.
Measuring two to three millimeters, the insects are so small that they can be difficult to see. Still, their bite can pack a painful punch.
Azusa resident Constance Yu described the persistent insects as “like little monsters but smaller” as she shot down the creatures during an interview. CBS News This week.
Although the flies cause discomfort, they are not known to transmit diseases in L.A. County, according to the Vector Control District.
Spikes in black fly activity are often caused by scheduled water releases from upstream dams, which are essential to the region’s water management but also create ideal breeding conditions for the pests.
The district monitors and sprays pesticides at breeding sites, including local rivers, streams and places like Morris Dam, and sets traps in foothill communities to track population size and minimize impacts to residents.
This time last year, there were single-digit counts of black flies in the monitoring nets. Now they’re catching more than 500 flies at a time, district spokeswoman Anais Medina Diaz told LAist.
Diaz also said it’s normal to see so much fly activity this time of year, noting that the increase is likely linked to the recent record-setting heat wave. Southern California is experiencing its warmest March temperatures on record, leading to an increase in snowmelt from the mountains.
“We’re experiencing them now because of the warm temperatures we’ve had,” Diaz said. “And of course, with all the water that’s going down through the river, we have a high flow of water that is not typical for this time of year.”
Black flies aren’t the only creatures causing trouble in unseasonably warm weather.
There have also been more rattlesnake sightings in the Southland, with two recent human deaths, as early summer attracts more snakes to hiking trails. A great white shark sighting off Newport Beach has sent sea temperatures soaring, leading to the temporary closure of the beach on Thursday.
