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Cicada Killers

Occasionally, I’ve come across a cicada lying on the ground, motionless, but seemingly alive and wondered how it got that way. Earlier this summer, I found out.

Cicada Tibicen abandoned by Cicada Killer

Cicada–motionless, but still alive?

In late July, I was standing on my patio when I spotted a wasp-like insect that was about 1 ½ to 2 inches (38 to 51 mm) long. Its body was brownish-black with yellow markings, and it had shiny, rust-orange wings and legs. It flew slowly back and forth just above the patio’s surface and then entered what appeared to be a freshly excavated hole between two patio stones.

I did a Google search on “large burrowing wasp”, and the first hit was a Wikipedia entry on Sphecius speciosus, a large digger wasp commonly known as the Eastern Cicada Killer. The description and photos matched the insect that I had seen.

Cicada Killers, true to their name, hunt and capture annual cicadas to feed their larvae. I usually start to hear the loud, raspy songs of male cicadas in early July. I learned that Cicada Killers emerge soon after. After mating, female Cicada Killers excavate burrows that will hold both their larvae and the cicadas that the larvae will feed on. They locate their burrows in well-drained soils, often in patios and sidewalks, and always near large deciduous trees where cicadas feed on sap.

Although the Cicada Killers are large and somewhat frightening looking, they actually are docile around people. The males don’t have stingers, and the females will deliver a mild sting only if handled roughly.

Excavating the burrow

Cicada killer Sphecius speciosus excavating

Cicada Killer pushes soil with her rear legs

The next day, I watched a female Cicada Killer excavate a new burrow beneath the patio. She entered a hole in the sandy soil between the patio stones and, after several minutes, backed out of the hole, pushing the soil with her spurred rear legs. She looked like a mini bulldozer working in reverse, and she amassed a quantity of excavated soil many times larger than herself. I read that Cicada Killer burrows can be up to three feet long and extend two feet below the surface. I also confirmed what I had read about their docility—I approached the female closely but she was oblivious to my presence.

Cicada killer Sphecius speciosus excavation

That’s a lot of soil to move

The hunt for cicadas

When her burrow is complete, the female Cicada Killer begins hunting. She hunts by sight and, after capturing a cicada, she uses her stinger to inject it with venom that both paralyzes and preserves the cicada, but does not kill it. Keeping the cicada alive keeps it in a fresh, edible condition for longer than if it were dead. The Cicada Killer flies from the tree back to the burrow with her prey—no easy feat, since the cicada is about twice the weight of its killer. After the larvae hatch, they begin to feed upon the paralyzed, still living cicadas that their mother has provided.

Female cicada killer sphecius speciosus hovers

Female Cicada Killer hovers over burrow entrance

Mishaps happen

Cicada Killers sometimes accidentally drop their heavy prey when flying to the burrow. Cicada Killers aren’t strong enough to take flight from ground level with a cicada in tow, so they often abandon it. They also may abandon their prey if they mistakenly land too far from their burrow entrance. The motionless cicadas that I’ve found were likely abandoned by Cicada Killers. Unfortunately for them, the paralyzed cicadas are easy prey for ants and birds.

Looking forward to next year’s show

During the several days that I saw the female Cicada Killer flying about the patio, I never witnessed her toting a captured cicada back to her burrow. Hopefully, she did so unseen, so that I can have a better chance of watching these fascinating insects again next year.

For more information

Professor Chuck Holliday of Lafayette College in Pennsylvania has an excellent website on the biology of Cicada Killer Wasps.

This, my third post about the Giant Swallowtail butterfly (Papilio cresphontes), will focus on the larvae.

Papilio cresphontes giant swallowtail young larva Dictamnus albus

Larva or bird dropping?

The young larvae are a shiny dark brown with cream-colored patches–they look like warty bird droppings. As they get older, the larvae develop scale-like markings about their heads and look like tiny snakes when viewed from the front. These disguises help to protect the larvae from predators—young larvae appear unpalatable and older ones resemble frightening adversaries. The larvae also can ward off potential predators by thrusting out their osmeterium, a pair of bright red, retractable horn-like structures. In older larvae, the osmeterium emits an unpleasant stench that repels potential invertebrate predators like spiders and ants. The osmeterium’s likeness to a snake’s tongue may frighten larger predators like birds. The Dragonfly Woman has a nice video on her blog of a larva extending its osmeterium.

Eastern Garter Snake Thamnophis sirtalis sirtalis

Older larvae mimic snakes like this Garter Snake

After molting through five stages, the larvae ultimately reach a stout 2 to 2 1/2” (51 to 64 mm) long. They then seek out a nearby vertical stem or other surface on which to pupate. In northeastern North America, the Giant Swallowtail overwinters as a pupa.

In Florida’s warm climate, where Giant Swallowtail butterflies are common, there are two or three generations each year. There, the larvae often feed on citrus trees like sweet orange and are called Orange Dogs. They’re considered pests because they can defoliate young trees.

Update on the larvae in my garden

Papilio cresphontes giant swallowtail larvae eating Dictamnus albus

Bulking up on Gas Plant

In my August 19 post, I wrote that I had found three Giant Swallowtail eggs on the Gas Plant (Dictamnus albus) in my garden, followed by two larvae about a week later. As of today, I’ve counted six larvae scattered on the leaves of the Gas Plant. Five larvae are about the same size—5/8” (16 mm) long. The sixth larva, which I discovered yesterday, is smaller, only about 1/4” (6 mm)  long. I suspect that the small larva may be the offspring of an adult female that visited my garden unseen several days to a week after the adult I saw on August 3.

The larvae often sit on the tops of the Gas Plant leaves, clearly visible bird-dropping imitators. Occasionally, one will appear restless, and will travel back and forth over the leaves for several minutes before settling down again. I’ve read that they feed mostly at night, but I occasionally have seen a larva munching on the Gas Plant leaves during the day. If I touch them with a twig, they arch their backs and thrust out their bright red osmeterium.

Papilio cresphontes giant swallowtail larvae red osmeterium

Red osmeterium deters predators

I’ll continue to monitor the larvae on my Gas Plant and hope to post occasional updates on their development.

Giant Swallowtails moving north  

I first thought the Giant Swallowtail butterfly that visited my garden on August 3 was a rare sight. Since then, I’ve learned that lots of people in my area and farther north have seen Giant Swallowtails this year and that sightings in the north have been increasing for about five years. This northward movement may be due to changing weather patterns, decreased pesticide spraying, or some other as yet unknown reason. Whatever the reason, we northerners have had the treat of seeing these large, beautiful butterflies close to home.

In my previous post, I wrote about a Giant Swallowtail butterfly that visited my backyard in early August, an unusual sight for my area. I sought to learn more about this butterfly species.

Adult butterflies seek out areas that contain their larval host plants, those specific plant species that females lay their eggs on and that their caterpillar larvae feed on. Per butterfly field guides, various members of the Rue (Rutaceae) family are the host plants of the Giant Swallowtail. The better known members of this family are citrus trees like sweet orange (Citrus × sinensis). That’s why the Giant Swallowtail is so common in Florida. Farther north, native members of the Rue family include Prickly Ash (Zanthoxylum americanum) and Common Hop Tree (Ptelea trifoliata). Continue Reading »

It’s always exciting to see a new species of plant or animal, especially one that’s considered rare in your area. This happened to me earlier this month, when a Giant Swallowtail butterfly (Papilio cresphontes) visited my northern New Jersey backyard. This large, attractive butterfly is common in Florida, but becomes less abundant farther north.

Giant swallowtail or Papilio cresphontes dorsal

Giant Swallowtail

Continue Reading »

Sometimes, nature comes to you when you’re least expecting it. This is the story of my chance, up-close encounter with a Tinkling Ground Cricket, a charming denizen of the woodlands of the eastern United States.

Discovering singing insects

Last year, I decided to learn more about the singing insects of my area—the crickets, katydids, and cicadas. There are several good resources (see the end of this post) guiding me in this enjoyable journey.

Common true katydid Pterophylla camellifolia

Common true katydid, a singing insect

To get warmed up for this year’s singing insect season, I read Cricket Radio by John Himmelman several weeks ago. It’s an entertaining and educational book that combines natural history and personal observations on crickets and katydids. I highly recommend it.

 

Continue Reading »

Milkweed (members of the genus Asclepias) flowers are unique and fascinating structures that attract a myriad of insect pollinators. The insects are rewarded with sweet nectar that milkweed flowers produce in copious amounts. Yet, insects sometimes cannot pull free from the nectar trough and perish in the grips of the milkweed flower.

Asclepias tuberosa butterfly weed w spicebush swallowtail

Butterfly weed, true to its name, with a spicebush swallowtail butterfly

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Alypia octomaculata eight spotted forester moth

Attractive insect in my garden

I first encountered the attractive insect in the above photo about 15 years ago, feeding on the flowers of swamp milkweed (Asclepias incarnata) growing in my garden. Here’s what I recorded in my notes—“black with two pale yellow spots on front wings and two white spots on rear wings; orange blobs on legs; about 1 ¼” wide; no large knobs on ends of antennae; beautiful!” I consulted several butterfly field guides but was unable to identify it.

 

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