Cicada killers on the prowl

A few days ago I noticed a fresh pile of dirt near one of my tomato plants. Looking closer I noticed a hole in the ground next to the pile. I recognized the excavation as that of a cicada killer wasp.

That’s a descriptive, but unimaginative, name for them since they really do kill cicadas. These wasps show up each year shortly after the cicadas arrive during the dog days of summer.

These are big wasps that make a lot of scary buzzing sounds when they fly. Entomologists tell us that they rarely sting even when provoked. Mine were certainly even tempered. But I’m not the one that is going to tell you that they won’t sting you. I seem to remember a few years back some experts telling us that stingrays in the ocean are harmless, but I digress.

I wanted to get a photo of the cicada killer when I first spotted it but it wouldn’t sit still long enough. As soon a I was able to get close enough to focus my phone camera, it would take off with the immobile cicada in tow. A few days later I forgot all about the wasp and was placing some straw around some of the tomato plants to keep the fruit off of the ground. Low and behold, there was a cicada killer, with a cicada, looking for a way to get into her tunnel. A shallow layer of straw slowed her down long enough for me to snap a couple of photos.

The straw slowed down the wasp enough for me to snap a photo of the wasp and her prey.
The straw slowed down the wasp enough for me to snap a photo of the wasp and her prey.
She found her way into the tunnel entrance.
She found her way into the tunnel entrance.

The female wasps are responsible for all the digging we see. They construct tunnels that are between six and 12 inches deep and can be three or four feet long, or even longer. That’s a lot of dirt for one insect to move all by herself. Often there are side rooms in these tunnels.  Not only does the female wasp dig the tunnels, she also does all the hunting for the cicadas. The male is unable to hunt even if he wanted to since he does’t have a stinger. He does help however by scaring away predators.

Once the female finds a likely victim, she plunges her stinger into the cicada, not to kill it mind you, but  just to paralyze it. She wants the cicada to be alive when her offspring eats it. Once the cicada is immobilized, the wasp flips it over so it is face to face with its prey. Even though the cicada can weight more than twice as much as the wasp, she is such a strong flier that she can lift it and fly with it to her tunnel. There she carries it down to one of the rooms and places it there as sustenance for her young. She then uses her stinger, which is actually an ovipositor , to lay an egg in just the right spot of the cicada.

The wasp grub hatches from the egg right away and quickly starts eating the cicada in such a way to keep it alive as long as possible. In a few days, there is nothing left but the hollowed out shell of the cicada. In the meantime, the grub has grown into a full size larva. If the grub is a female, she gets to eat a second cicada.

Once mature, the larva spin a cocoon and pupate underground until next summer when they emerge as an adult wasp. Like many insects, the adult wasp has a different diet than its larval stage eating only tree sap and nectar from flowers. They don’t even take a nibble from the cicadas they kill.

Cicada killers prefer sandy soil with sparse vegetation — that pretty much describes my weed-free tomato patch. Also there needs to be trees nearby with cicadas in them to provide hunting grounds.

Bob

 

Sphinx moth caterpillars

When you spend a lot of time outdoors in the garden, you’re bound to run across some interesting things from time to time.

This week I was working around some grapevines. In one area I was cleaning up neglected rose bush pulling out an assortment of weeds including a small wild grapevine. It was there I found the odd-looking, pink caterpillar of a Achemon sphinx moth munching on grape leaves.

The next day I was moving a few small grapevines from one location to another and found two more caterpillars, one orange and the other green. One was another Achemon the other looked to be a Virginia creeper sphinx moth. They are closely related to each other and both are related to tomato hornworms, as you could probably guess that by the horn on their posterior.

It’s been a few years since I’ve seen these even though there are a lot of grapes in our area. I usually have to travel to another area to see them and that was the cases this week.

A pink caterpillar this size really catches your eye. Here the caterpillar's "horn" has shrunk down to resemble an eye.
A pink caterpillar this size really catches your eye, over two inches long. Here the caterpillar’s “horn” has shrunk down to resemble an eye.

Because they are so big at this stage, they can eat quite a bit but not enough to do any real harm to the grapevines and harvest size is not affected by their feeding either. They will keep eating and get bigger. In a week or two when they are full size, they will burrow into the soil then form a pupa. There they will stay until next summer when they will emerge as a large moth.

The yellow caterpillar was feeding on concord grape leaves.
The second caterpillar was feeding on concord grape leaves.

If left alone they have the potential to overwhelm a vineyard but their numbers are kept in check by parasitic wasps. Those wasps deposit their eggs into the caterpillar’s body where the eggs hatch. The young wasp larvae then feed on the caterpillar and eventually complete their larval stage of life.

Like a lot of moths, they are only active at night sipping nectar from flowers. Although I’ve only seen a few at night, I occasionally have found them in the morning clinging to a walls near a flower garden. One time I even found one inside, it must have flown in when someone open the door.

I ended up moving the caterpillars to an old, well-established grape vine where I knew they couldn’t do any harm. Once they settled down from all the ruckus, they went back to happily munching  leaves as if nothing happened.

Bob

 

Join the International Monarch Monitoring Blitz

By now I’m sure you know we are in danger of losing the monarch butterfly migration in our lifetime. This critical situation was addressed in 2014 when President Obama met with President Pena Nieto of Mexico and Prime Minister Harper of Canada about it. At that meeting they agreed to “to establish a working group to ensure conservation of the monarch butterfly”. Since then much has been done to encourage research into the habits of monarch butterflies. One such result is the establishment of the annual International Monarch Monitoring Blitz.

This is an event that takes place all across the range of the monarch butterfly that spans large parts of  The United States, Mexico and Canada. The purpose is to try to get a count of the number of monarch butterflies during a small window of time. This year the count started July 28th and runs through August 5th.

Scientists are looking for help during the Blitz, they’re asking for “citizen scientists” to step forward and pitch in for the butterfly count.  It’s simple and fun to participate as a citizen scientist, anyone can do it. All you need to do is count the number of monarchs you see in all stages of the insect’s development; egg, larva, chrysalis and adult and make some observations about milkweed plants. Once you’re done, report your findings online at the Monarch Larva Monitoring Project website.

There’s another one! Add him to the tally.

This is only the second year of this international event, so now’s your chance to get started as an amateur researcher. Years from now as the Blitz expands and becomes more well known, you’ll be able to proudly tell your friends you were among the earliest participants.

We’re working on our part of the Blitz right now  and hope you find the time to join in too. It’s a great way to spend some time outdoors while knowing you’re doing something tangible to help save our beloved monarch butteries.

Bob and Judy