They're back!

They've returned ... unfortunately ... for the third summer in a row.  While walking through our yard a few days ago I first saw them buzzing around our lawn.  Then I saw the piles of dirt from the new tunnels.  Our dreaded cicada killers have returned to mess up our lawn once again.  By the end of August our backyard will look like a battle zone with piles of dirt from tunnels all over.  Then when the activity ceases I will once again try to dig the areas up and plant grass seed once again.  If I am fortunate, by next June it will look nice again - at least until they hatch for the fourth year.  Last year I wrote a blog about these unusual wasps.  But in case you missed it or have never seen them in action, here are a few facts for you to ponder. Adult eastern cicada killer wasps are large, 0.6 to 2 inches long.  They are robust wasps with hairy, reddish and black areas on the thorax (middle part), and are black to reddish brown marked with light yellow stripes on the abdominal (rear) segments. The females are somewhat larger than the males, and both are among the largest wasps seen in the Eastern United States, their unusual size giving them a uniquely fearsome appearance.  Cicada killer females use their sting to paralyze their prey (cicadas)   Adults emerge in summer, typically beginning around late June or early July and die off in September or October. They are present in a given area for 60 to 75 days, usually until mid-September. The large females are commonly seen skimming around lawns seeking good sites to dig burrows and searching for cicadas in trees and taller shrubs. Females may share a burrow, digging their own nest cells off the main tunnel. A typical burrow is 10–20 in deep and about 0.6 in. wide. As much as 100 cubic inches of soil may be brought to the surface as tunnels are formed. In digging a burrow, the female dislodges the soil with her jaws and, using her hind legs, pushes loose soil behind her as she backs out of the burrow. Her hind legs are equipped with special spines that help her push the dirt behind her. The excess soil pushed out of the burrow forms a mound with a trench through it at the burrow entrance. After digging a nest chamber in the burrow, female cicada killers capture cicadas, paralyzing them with a sting. After paralyzing a cicada, the female wasp holds it upside down beneath her and takes off toward her burrow; this return flight to the burrow is difficult for the wasp because the cicada is often more than twice her weight. After putting one or more cicadas in her nest cell, the female deposits an egg on a cicada and closes the cell with dirt.  New nest cells are dug as necessary off of the main burrow tunnel and a single burrow may eventually have 10 or more nest cells. The egg hatches in one or two days, and the cicadas serve as food for the grub. The larvae complete their development in about 2 weeks. Overwintering occurs as a mature larva within an earth-coated cocoon. Pupation occurs in the nest cell in the spring and lasts 25 to 30 days.  Large aggregations of cicada killers can build up over time. An estimated 40% of the developing larvae (a dozen or more per tunnel) may emerge as adults the following year so numbers can increase rapidly.  These wasps will stay and thrive where their basic needs are met. Even if aggressive control measures kill the inhabitants, the site will remain attractive to new settlers in ensuing years.  I guess that is why we can't beat them - we've tried sprays, a wiffle ball bat and even an electrified tennis racket - yes, you've read that correctly.  But nothing has been successful.  I just have one question.  Why did they choose our lawn to infest?  Neighboring areas have been left to clover and dandelion and other weeds.  Why don't they nest there?  Maybe they just like areas that were once attractive and well kept.  Ok, that's enough writing for today - guess I'll go out back and swing my racket for awhile.