Dog Day Cicada Time

 

Dog day or annual cicadas are starting to get noisy outside. Males are singing to attract mates. There's more than one kind of annual cicada, with different species singing different songs and at different times of day or night. They sing with an organ called a timbal which is made of ribbed membranes that change shape with a click when pulled on by muscles. The clicks are amplified by hollow chambers in the insect. Click to enlarge. 

Here's a periodical cicada for comparison -- not what's singing now. These are the famous red-eyed ones that emerge in spring and early summer in 13 and 17 year cycles.

Some annual cicadas appear every year, but life cycles of individuals take from 2 to 5 years. They begin as eggs laid in slits on tree branches. (After the singing and mating is done.) The eggs hatch, nymphs fall to the ground and burrow down. They suck juices from plant roots, and eventually reach their last nymphal stage. Then they dig their way back up above ground, climb onto something and shed their skin and emerge as adults.

But here's a problem for dog day cicadas -- a big wasp known commonly as the "cicada killer."At about an inch and a half long, the cicada killer is one of our largest wasps. The huge size makes them look dangerous, but they are not aggressive -- except to cicadas.

When a female cicada killer is ready to lay eggs she digs a nest in the ground. (Lawns, planting beds, and the edges of concrete slabs are favorite sites.) Then she hunts for a cicada. She will sting it to paralyze it and then carry it to her nest. She'll push the cicada in and may go back to find another. After the nest is provisioned to her satisfaction she lays eggs on the paralyzed prey and seals the nest.

The eggs hatch into larvae that feed on the fresh cicadas their mother left for them. Then, plump and satisfied, the larvae become pupae and spend the winter underground. They dig upward to emerge from the nest the following summer. They fly around sipping flower nectar until the time comes to breed -- and to hunt cicadas. 

Cicada Killer

Here's an interesting insect from the summer of 2015 -- a big wasp I passed on a hot day in August. It's Specius specious, commonly called the eastern cicada killer or cicada hawk. 

At about an inch and a half long, the cicada killer is one of our larges wasps. Their huge size makes them look dangerous, but they are usually not aggressive and do not often sting us. They are solitary wasps that live alone; they lack the hive-defending sting-whatever-comes-close attitude of the yellowjackets they are sometimes mistaken for.

I saw this cicada the same day. It is also a really big insect, up to about two inches long.  Click on the photos to enlarge. 

It was not accident that I saw both of these on the same day; they are intimately associated. When a female cicada killer is ready to lay eggs she digs a nest in the ground. (Lawns, planting beds, and the edges of concrete slabs are favorite sites.) Then she goes out hunting cicadas.

She stings a cicada to paralyze it and then carries to her nest. The flight is laborious because the cicada is so big and heavy. The wasp will sometimes land along the way or stop to rest, holding onto the prey. Back at the nest, she pushes the cicada in and may go back to find more. After the nest is provisioned to her satisfaction she lays eggs on the paralyzed prey and seals the nest.

The eggs hatch into larvae that eat the fresh cicadas. Then, plump and satisfied, the larvae become pupae and spend the winter underground. They emerge from the nest the following summer, digging upward, and fly about eating flower nectar and plant sap until the time comes to breed, and hunt cicadas.

Check out how this wasp is resting with its front legs folded up to its shoulders. Maybe wasps do that all the time and I never noticed until I watched a giant.