Q: On the new leaves of our curassavica that are rooting there are “herds” of what I might call “ticks” (on the bottom side). They appear to have the same yellow-gold fluid when crushed as the aphids that we are used to. The body is about 2 mm across, six legs, segmented antennae, two “horns” protruding from rear: three large scale photos (~50 KB each) at: http://asclepias.homestead.com/mar2002.html They do not move that we can tell.
A: It’s the oleander aphid Aphis nerii. These are parasitized by a small wasp – Aphidius colemani. Keep the leaves in a closed container and the wasps will emerge in a few days. The wasp larva has pupated inside the body of the aphid and when the adult wasp emerges it will cut a circular flap toward the rear of the abdomen of the aphid and will pull itself upward out of the whole. The wasps are extremely small and are sold commercially to control aphids in greenhouses. Unfortunately, these parasites do not control the aphids well outdoors.
(My apologies, but I received this second-hand and don’t know the names of the contributors. If they would care to let me know, I would be happy to credit them.)