Yellow Aphids On Milkweed. The plump yellow orange sapsuckers known as milkweed aphids don t specialize in milkweed but seem to be skilled at finding it. They damage the plant by sucking liquid from the plant eventually stressing the plant and killing it when infestation is high.
Oleander aphids are bright yellow with black legs antennae and cornicles tail pipes figure 2. Aphids come in a variety of colors yellow red black etc. Just how do aphids build up their populations so quickly.
In these cases they may weaken the plant even further and greatly decrease the nutritional value for your caterpillars.
They won t spread to your other plants. Milkweed aphids now are well established in the u s. We have had larger caterpillars eat the plant aphids and all. The ants collect honeydew from aphids like we collect milk from cows.