Aphids, "Mummies" and an Ant
There are many different sizes of aphids in this photo. By going through asexual reproduction (called "parthenogenesis") an adult aphid can produce up to 80 nymphs in a week! Ants often "milk" aphids by stroking them with their antennae. The aphids give off honeydew, a sweet liquid obtained from the plant juices, which the ants like to eat.
I had seen several of these strange-looking, brown aphids on my milkweed leaves. While researching about a parasitic wasp, I came across a photo like this, I was amazed to learn that it is an "Aphid Mummy", an aphid that had been parasitized by a tiny Brachonid wasp. If the exoskeleton of the aphid was opened, a small wasp larva would be revealed. Sometimes truth is stranger than fiction!
The little black "tubes" protruding from the back end of the aphids are called cornicles, which are used for releasing a fluid used in defense (see previous photo).