Controlling the scourge of black flies

Added: 2026-05-12

[00:00:01]The Greater Los Angeles County Vector Control District promotes the health of the residents of the cities we serve by combating mosquito and vectorbor diseases. We do this through direct service to our residents uh by performing surveillance of different mosquito and vector species providing control and also educational outreach events.

[00:00:22]>> Today we're doing an an a survey or an assessment of the Auroro Seiko to determine the blackfly risk. In other words, how much blackfly could hatch off as an adults and whether or not we should uh consider this for a laridal treatment. So, we are looking for blackfly larve, blackfly pupé, and blackfly adults. We're going to be looking at substrates in the Aurora Seiko right here. So, we're going to look at um hair algae, trailing vegetation, the bottom of the creek itself, and uh uh rocks past flowing water.

[00:00:53]Blackfly like nutrientrich flowing water. The larve hang out these little fans that that collect particles in the water and they feed on that. So they need a high flowing water. Uh and that's exactly what we have here. And we have had history of uh large plumes of uh blackfly coming off these if we do leave it untreated. Uh and so it's part of our mandate that we we do this control for the city.

[00:01:15]And if we allow uh large number of numbers of adults to um to hatch off, it can create quite a nuisance for uh residents in this densely populated area. Uh I mentioned it's in the LA River that cuts through downtown LA. Uh so you can just imagine the number of people millions maybe that would affect if these adults come off. These blackfly can vector um disease. So ankos psoriasis or African river blindness is a is a possibility. You know uh we're not really so concerned with it here.

[00:01:41]But we do have the blackflies here. So it is always a possibility. Blackfly uh they bite. They they are they can be very uh piferous or they're a nuisance to people. uh and they they like to bite around our face, our eyes, and and they have a very painful bite. We've noticed a large population of of larve. Uh so we're going to recommend to our operations department to do a laride treatment here. Uh and we choose specifically do a larverside instead of a delta side uh because it's more targeted. It uses a bioactive that um pretty much only targets uh mosquitoes and and blackfly. So the mayflies in the river and some other insects will be safe. This did go untreated. we could see uh some large adult populations uh come off of this.

[00:02:25]So uh we've come back from the LA River or actually the Aurora Seiko which is a tributary of the LA River. Uh we've collected some blackfly. Uh we have uh some eggs that I have collected yesterday. Uh and some of the blackfly that we larvy that we collected today and we're looking at just the different uh morphological features on on the uh the larve to to do the identification.

[00:02:45]The same with the pupil casing. Uh we'll look at things like the gill, the number of gil filaments, uh different morphologies or or the different physical characteristics of the of the uh larve or the pupy and we use that to identify it down to species. Today was a good day. That was the most blackfly I've seen in the Aurora Seiko. And with that warmer weather also, the metabolism of the insects speed up so their life cycle will shorten.