Creature Feature

The Four-Toothed Mason Wasp 

I have a favorite camera lens, a 60mm macro. It was the first one that I purchased along with my first digital SLR camera. The camera is long gone but I still have the lens. A macro lens encourages me to see details that I would normally look past. 

Today, I was taking a walk around Jug Bay’s Glendening area and spotted a wasp that seemed ready to attack a bumble bee. The bee was in a nesting chamber and was blocking its home with its head and thorax. That wasp was an interesting one: a four-toothed mason wasp. 

The four-toothed mason wasp is a solitary wasp. They meet up twice a year with the opposite sex for less than an hour. Other than that procreative time, they are on their own.  

The insects are all black except for two collars of white. The female wasp has a painfully poisonous stinger but the male has no poison. Adults are vegetarians, living on nectar and pollen. Only the young, the pupa, are insectivores.  

The care of the pupa is interesting. This type of mason wasp prefer the unused nesting chambers built by bumble bees and other species of mason wasp to making their own. If they cannot find an unused chamber, they will remove the current residents by force— which is what appeared to be happening with the wasp I saw today.  

When the gravid female finds an adequate nesting chamber she will lay one egg and then fill the chamber with paralyzed caterpillars. A mud wall is added to block the tube-like structure and a space is left which is then capped with a second wall. The female lays about 20 eggs twice a year. The male wasps emerge from the chamber before females. The gravid female can tell the sex of the egg and will chamber the males separately. The offspring that are laid in the early summer mature and lay their own eggs in the fall. The pupa in those chambers don’t emerge until the next spring. The extra chamber may help with fending off the cold.  

I do not know how the four-toothed mason wasp got their name, except its mandibles have pointed projections. The mason wasp is not aggressive and rarely stings but resembles the white-faced hornet which lives in a colony and will swarm to attack when disturbed.