These flies were found mating outside my house in Savannah, GA in July 2009. They were oblivious to the fact I was taking a photo of them with my camera phone just inches away from where they were doing their business. haha.
These are a mating pair of Oleander moths, also called Polka-dot Wasp Moth.
The caterpillars are orange with long black tufts of hair. They can reach 2″ long. They do tend to stay in clusters. While the caterpillars eat oleanders and Devil’s Potato (Echites umbellata), the adult moths feed on nectar of flowers especially asters.
Since you have a mating pair you might be interested in an unusual thing about this moth. Most moths find each other using sex phermone chemicals. In this species, female moths emit an ultrasonic acoustic signal which we can not hear, but attracts male moths from great distances. When male and female moths are within a few meters of each other, they begin a courtship of calls which continues until mating occurs two or three hours before dawn.
This insect is only found in the southeastern states, tho a few have been found in Texas.
As anonymous indicated this caterpillar can be a pest in Florida and coastal Alabama. Not sure if you have that big of a problem with them in GA.
In light to moderate caterpillar infestations, damage to leaves is seen as small holes chewed between leaf veins. In severe cases this caterpillar can strip the shrub of leaves and small stems in a short time period. However, this shrub is very sturdy, so shrubs rebounded after being mostly defoliated. Severity of damage to your shrubs and frequency of oleander caterpillar infestations will determine which methods of control to take.
If you only have few caterpillars, pick them off and put in soapy water. If there are many, you can prune the branch where they cluster and put it in a bag then tied shut and disposed of. If you have a lot of caterpillars you can treat with BT. It may have to be applied several times to kill each generation. You might also check the label of Spinosad another organic bacterial insecticide.