Common Aerial Yellowjackets derive their common name from the fact that their nests are often aerially constructed, unlike the underground yellowjackets we’re more familiar with. Being in the same genus, it’s not surprising that Bald-faced Hornets and Common Aerial Yellowjackets build nests that are almost identical. The nests of both species have two to six horizontally-arranged layers of comb (for eggs and larvae) inside several layers of protective paper envelopes. The easiest way to tell which species made a nest is to see if there are yellow (yellowjacket) or white ( hornet) markings on the residents. The yellowjackets on the outside of the nest in the photograph are all busy making paper-mache out of wood fiber and applying it to their nest in order to enlarge it.
There are basically two groups of wasps: 1) social wasps, such as hornets, yellowjackets and paper wasps and 2) solitary wasps, species that live solitary lives and typically hunt prey for their larvae (the adults consume nectar). Mud daubers are a type of solitary wasp. Organ Pipe Mud Daubers builds cell out of mud in which they put prey (usually spiders) that they have stung and paralyzed, but not killed. They then lay an egg on top of the spiders, and seal the cell. After the egg hatches, the larval wasp consumes the still-fresh spiders, pupates, emerges as an adult wasp and chews its way out of the cell. In this picture a female Organ Pipe Mud Dauber wasp has collected a ball of mud and is applying it to the most recent cell she is making. The name “organ pipe” comes from the shape of the “pipes”, which consist of several cells, placed end-to-end, with the most recent cell at the bottom. (Notice the new, wet mud is darker in color.)
The European paper wasp (Polistes dominula) was introduced to the New Jersey Pine Barrens in 1968, and has since spread throughout most of the North America. Considered an invasive species by most entomologists, it looks more like a yellowjacket than the paper wasp that it is. The European paper wasp nests earlier in the spring, in a wider variety of nest sites, and feeds on a larger variety of insects than native species of wasps. In the photograph if you look closely you can see that it is scraping off a fine line of dead plant tissue on the underside of this leaf, assumedly for use in expanding its paper nest.