Wednesday, August 25, 2010

Wasps and water

After a cool, foggy summer, northern California seems to have decided to make up for all the lost heat in two days. Yesterday it was 106 degrees F (41.1 C) here in Santa Rosa. After lunch I dragged myself outside to water our lettuce and carrot seedlings and noticed a lot of wasp activity in and around the bird bath. After the sun had moved to the other side of our house, I spent some time (in the shade) spying on the wasps in my garden.

Our front yard has plants that attract honey bees (Apis mellifera), California carpenter bees (Xylocopa sp.) and the paper wasps (Polistes dominula). On sunny afternoons they all buzz harmoniously about some sages and oregano, drinking nectar. I've also noticed that the wasps spend a good deal of time visiting our lettuce patch, landing on the leaves and moving about for a minute or less then leaving. During our heat wave the wasps, and only the wasps, have been drinking and lounging in the water in our little bird baths. There seem to be three approaches: 1) fly by, dip toes in water, then land on edge of container and drink, 2) drop onto the water and float for a bit while sipping, 3) hover above the water, dipping frequently to sip. The wasps appeared to be utterly unconcerned by my presence. I sketched some more this afternoon, as the coastal influence began to reestablish itself (the fog's returning!), and was interested to note that the wasps stopped drinking from the bath when the temperature dropped into the mid- or low 90s.

These wasps are recent immigrants to our continent. Natives of Europe, they somehow found their way to Massachusetts in 1981 and then spread across the country with great haste. In some areas of the northeast they appear to be replacing native paper wasps. Their long hind legs and slender bodies make it easy to distinguish them from the similar looking yellow jacket (Vespula sp.).

Oh, and as to why they hang out in our lettuce? We often water it at noon on warm days. I suspect that the wasps find the sheltered, shaded source of water appealing at that time of day.

For more information than you'll ever need about European paper wasps, check out these web sites:
Living with bugs
Penn State College of Agricultural Sciences
Michigan State University
Garden Friends & Foes
Bug of the month: Articles about Pacific Northwest Insects


  1. I have a lot of wasps visiting my water garden and acting just as you describe. Some land in the water with an audible plop and after floating for a while, swim over and climb onto a water lily leaf before flying off.

  2. Great observational sketches, Debbie. They drink from Dermott's bowl here. I'm always afraid he is going to swallow one. I have trouble keeping them away when he is having a bone outside too. And fighting them for my chicken when we dine outside.

  3. You mentioned the wasps were unconcerned by your presence. I'm glad you reciprocated the lack of concern and observed, drew and annotated all this fascinating activity. I could never hang around wasps long enough to observe anything at all.

  4. Lovely and educational as always. I hope you have a great weekend and Holiday.

  5. Next time we roast I need to put some water down low where I can watch it! My bird bath is to high to peer into. What a facinating post.