White flies...a real and pernicious pest on our lotties here, but what are they? How do you recognize them? Finally, what can be done? White fly sorts fall under three groups: Aleyrodinae, Aleurodicinae and Udamoselinae. These sorts get onto a number of different plants, but they are very interested in brassicas...and the type known as Aleyrodes proletella is the white fly type with which I will focus on here today. For those who do not know this pest—it is a small flying insect about 1.5 mm long. Its wings are covered with a white, waxy powder. It is larger than the white fly that one finds in greenhouses. Its wings have four light grey, almost imperceptible spots on them. The Pest The larvae of the white fly are laid in a circle, (usually) on the underside of the brassica leaves. It is important to note here that the Aleyrodes proletella almost exclusively infest three specific sorts of brassica—the Brussels Sprouts, Savoy Cabbage and Kale. The larvae and pupae have a thick layer wax over them. It is common to see the insect in all three stages. Damage The white flies expel honeydew which makes the leaves sticky and dirty. Fungi can colonize and under this condition. The flies bore into the phloem for nourishment. Their saliva is mixed-in and the plants react to this toxic substance whereby the leaves loose their turgor and become flaccid. The leaves will eventually; one for one, turn yellow and fall off the plant. Life Cycle The female adults lay technically living larvae (some folks refer to these as ‘eggs’). They can lay up to 200 at a time. At any rate, the larvae eventually come out of this stage and sort of wander over the leaf for a couple of hours, looking for a place where they can begin sucking phloem. When they shed their first skin, they anchor themselves and will serious feeding. At one point, it will be time to pupate in this same place. An entire cycle will last from twenty to forty days, depending on the temp. The bad news here is that white flies over-winter on living green plants. It is such a shame for those of us who want to harvest veg throughout the winter months. Well, it is what is is, and so we must take steps to protect our crops. What To Do --Obviously, you want to get rid of as many green plants as possible in your garden to limit the overwintering possibilities for the flies. Sadly there are other plants like, strawberries, azalia’s and rodi’s where they will set up shop. --Pyrethrum is widely used and is effective. It does kill other types of insects though. --Green soap with or without spiritus. --Check the tops of the plants frequently and remove leaves with colonies. --Use a very fine gauze over your plants. --Use white flies’ natural enemies such as the Encarsia formosa. One can order these commercially. --You can use those rolls sticky of flypaper like you use for flies in your home, which will attract and stick them. --I have even heard of folks using a Hoover/ vacuum cleaner or a small one like you suck up ashes or cookie crumbs off the salon table. --One can also simply use water that spurts hard out of a hose or sprayer to irrigate them off the plants. I have done this as well as used soapy water. --I also go to the lottie on a cold and windy winters' day and shake each plant...they fly up and the wind blows them away. The key to success is to keep treating them. You have to do this because unlike aphids they have various stages of development, and if you spray; for example, you may kill those present at that moment, but later pupae and larvae will hatch out of their old stage and emerge unscathed to continue their life cycle. Now, a few images: To begin with let me introduce my chalky friend: You should check your brassica's frequently, especially the leaves in the top of the plant. You can see on this picture and others, the white area in contrast to the dark green of the leaf perimeter/tip. That is the web "blanket" that goes over and protects the larvae. The top or bottom of the leaves is where they can be found in their communities. In this foto you can see the beasts in the three stages of their life cycle. Again the protective white net is visible. Finally, after spouting them with a hard stream of plain water you can see these peculiar balls of water mystically coated with the tiny particles of the white waxy powder of the wings of the white flies. Amazing stuff. I couldn't believe my eyes the first time I saw this phenomenon. It looks like some kind of bizarre, if not harmful chemical. I hope that you guys do not get this pest, but if you do--something can be done. Just don't give up.