Bromeliads: 200 mozzies per day

A friend of mine has a beautiful garden – he and his partner are very talented gardeners. Outside their property along the road is a 6 foot wide bed of plants about 100 feet long, many of them bromeliads. So, I went over there today with a turkey baster and did some sampling. In one small bromeliad, I found just over a dozen larvae. In another, I found a similar number. To get these larvae, I sucked up as much water as I could from the center, and a few of the leaf wells. So it’s reasonable to assume that I got maybe half of them – the small larvae were probably hiding deeper than I could reach, and the pupae are fast and so could escape the suction. (With the turkey baster, you never get all the water).

So let’s just say for the sake of argument there are 25 mosquitoes in larval or pupal form in each plant. Along the road, I estimate there are at least 100 bromeliads of this type. So, that of course means there are something like 2500 mosquito larvae and pupae there. Since on average it takes about 12 days to go from egg to adult, this means at least 200 adult mosquitoes per day are hatching from that one bed of bromeliads. And even though we’ve had little rain recently, the leaf wells had lots of water in them. So these bromeliads are going to keep producing mosquitoes even when it’s dry.

Food for thought.  I’d encourage everyone to grab a turkey baster, and maybe a fat straw to stick on the end, and go out to your nearest bromeliad and see if you can find larvae.


So what can you do?

Assuming you don’t want to pull all the bromeliads out, you can sprinkle them with BT (Mosquito Bits, lasts 14 days). There are also
liquid forms of BT that you can spray that might be more effective at reaching the hard to get broms.  Be aware that BT is harmful to caterpillars (larval stages) of both good and bad insects, so it might be best to use the Bits.

Personally, I would pull 99% of the bromeliads out.  Keep a few choice specimens that would be easy to treat and monitor.  We have so many beautiful plants here, we can choose some that are not mosquito factories and still have a fabulous garden.

What about soapy water or bleach water?

These don’t work.  The DOH was telling people to use soapy water until the CDC told them to stop saying that.  Now, they are telling us to use bleach water, but research shows the concentration of bleach required to kill larvae is really, really high.  So it isn’t going to work!  Just use BT.


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