Wasp Nursery Constructors

     Two interesting and attractive kinds of wasps, including paper wasps and organ pipe mud dauber wasps, build nurseries for their young here in southeastern Pennsylvania, as well as in much of eastern North America.  These wasps have characteristics in common, including having thin "waists" where their thoraxes meet their abdomens and building nurseries that are common and fairly obvious in sheltering, human-made constructions.  Adults of each kind can sting, but are not usually aggressive.  Adults of each species sip flower nectar in open, sunny habitats, while their larvae are carnivorous.  But the wingless youngsters consume different prey, thus eliminating competition for food between them.   
     Paper wasps are three-quarters of an inch long and reddish-brown, with yellow rings of color on their thoraxes and abdomens.  In spring, cooperative groups of several fertile females work together to make nests of chewed wood pulp and their own saliva.  Each of these paper-like nurseries of several cells per nest is open underneath where adult wasps feed the young, but covered on top and hangs by a thin strand of paper from the ceiling of an over-hanging boulder, or a porch roof, a pavilion, a bridge or some other human-made construction.  These hanging nests protect the larvae from rain and wind.  
     One female paper wasp of each group becomes queen and lays an egg in each paper cell.  The first couple of generations of larvae, per summer, are all females, cared for by unmated female workers of each colony.  Adults feed young wasps insects they caught and pre-chewed.  Young wasps get lots of protein that they will grow on.  Adult wasps and their progeny do not compete for the same food. 
     Fertilized eggs become females and unfertilized eggs become fertile males. At the end of each summer, only mated young queens overwinter in the ground under leaf litter, or in stone walls.  They start new colonies of paper wasps the next spring and summer.  Old queens, female workers and males die in the frosts of autumn.
     Organ pipe mud dauber wasps are about an inch long and iridescent-black.  Each solitary female wasp of this species builds a few long tubes of mud on a smooth, vertical surface under a boulder or roof that will protect her offspring from rain. 
     Each mud dauber female rolls mud into balls and carries each one separately in her mouth to her chosen location to build her nursery.  Mud ball after mud ball is added to each tube and those tubes are plastered vertically together, making them look like joined pipes on a tiny organ, hence this wasp's common name.      
     Each dried tube has a few cells in it, and each cell will harbor a wasp larvae.  After making those mud tubes, each mother pipe organ wasp places a spider she paralyzed into each cell and lays an egg on it.  Then she closes the cell with mud.  The hatched youngster feeds on the spider, pupates in the mud cell and later emerges as a mature wasp ready to carry on the species another generation. 
     Paper wasps and organ pipe mud dauber wasps have intriguing life histories, as all life does.  And when readers find their nests under sheltering, human-made objects, admire their works, and the wasps themselves; but there is no reason to be afraid of them.  Just leave them alone.