Insects never have boring lives. Mud daubers set a great example. These busy wasps build their nest chambers out of mud. Here in two separate videos you can see the two stages of nest construction:  Gathering mud by Sceliphron caementarium filmed in Athens, GA, USA.  Construction of the nest chambers by Sceliphron destillatorium from Canary Islands.
The genus Sceliphron is found in all of the temperate and tropical continental areas of the world and on many islands (some have been introduced by humans). Thirty species are known. Most occur in the Old World. Females build their mud nests in a quite diverse sheltered and dry sites including human dwellings. Construction starts with a single chamber. Once the chamber is complete the female wasp provisions it with orb weaving spiders (see the short video at the very bottom for an orb weaver Araneus diadematus). After sealing the chamber work begins on another cell. In the end an aggregated nest is formed. Cells that have not been fully stocked in one day may be temporarily sealed at night.
It is a wasp eat wasp world and S. caementarium has her own natural enemies. It has been documented that about half of the mud-dauber nests are parasitized by an ichneumonid wasp Acroricnus seductor.
The following video is an excellent summary from Sceliphron destillatorium. Using still frames the entire nest building process is condensed into a 15 minute sequence:
Wasps can produce quite potent chemical defense compounds. Some solitary species have been the focus of research exploring for new antifungals and antibiotics.
Solitary wasps are also known for their unusually large brains. Brain structures called mushroom bodies were first noticed in Hymenopterans (ants, bees, wasps and sawflies) by Felix Dujardin in 1850. Mushroom bodies are now suspected to have the same ancestral origin with the cerebral cortex of the mammalian brain responsible from higher cognitive abilities.
According to the social brain hypothesis size of the social group also determines the size of the brain. This applies to primates. However in the world of wasps being solitary seems like the major driver of brain size. Indeed if you look at the evolutionary tree of Hymenopterans a very large fraction of the branches consists of solitary living parasitoids (social life evolved at least ten times). These are parasitic wasps that lay their eggs into the bodies of other insects and arthropods. It seems transition into a parasitic way of life throughout the evolution made their brains larger. This transition probably happened about 90 million years ago at the very start of the Jurassic period.
Brain is a very expensive organ. Just to give an idea, brain of a sleeping human baby consumes 60 percent of the total energy budget of the body. Then what might be the selective advantage of having a bigger brain for a parasitoid wasp? Wasps need a good memory for places and locations to find homes, food and mates. Solving such spatial problems requires a cognitive map.
Being a predator/parasitoid poses some challenges. A great majority of wasps are visual predators therefore finding prey requires formation of a search image. Studies have shown that even fruit flies with much smaller mushroom body can perform cognitive abilities such as context generalization (filtering background noise in order to pay particular attention to an object) and positional invariance (recognizing same object no matter how far). Clearly a wasp requires a much larger capacity for prolonged attention in order to track and ambush prey. For instance, if the prey is hiding inside the crack of a log it needs to use other clues like sound and smell in addition to visual.
Heavy predation pressure from wasps has forced spiders to evolve predator avoidance measures such as defensive structures on their webs. In a different species of spider researchers have observed that decorations weaved on the web decreases accidental damages caused by birds flying through. On the other hand same decorations increased the predation rate from wasps.