Ron Wilson

Ron Wilson

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Stranger Things in the Forest - Buggy Joe


The name “scorpionfly” sounds like a dangerous combination. Like some freakish creature buzzing out of the Upside Down or lurking in a Jurassic dominion. Of course, scorpionflies aren’t flies with scorpion stingers just like pineapples aren’t apples growing on pines. The contractions tell a story; pineapples were so named because they resemble pine cones.

 

Flies belong to the insect order Diptera (di=two; ptera=wing). Flies have two wings and their common names are written as two words: snipe fly, hover fly, house fly, horse fly, etc. The common names for insects that fly but are not Dipterans – they have four wings – are written as contractions: butterfly, whitefly, sawfly, etc., and of course, scorpionfly. I believe shoofly pie fits the rule but I need to do more hands-on investigating.

 

Scorpionflies belong to the order Mecoptera (meco=long). They have four long wings. Male scorpionflies have external genitalia at the end of their abdomen that resembles the stingers of scorpions. Scorpionfly adults feed on nectar and dead organic matter such as dead insects; however, some will also behave as predators by chowing down on living insects.  These unusual-looking insects commonly hang out on low-growing vegetation along the edges of woods often near streams.

 

 

 

The name “snipe” invokes a mythical forest creature that's only ever been seen by summer camp counselors and older siblings. However, I’m referring to an authentic creature known as the Golden-Backed Snipe Fly (Chrysopilus thoracicus, family Rhagionidae). You may be rewarded on your snip hunt by looking in the same locations where you find scorpionflies.

 

 

The "golden-backed" in the common name refers to the highly reflective golden hairs covering the top of the thorax. Its scientific name also describes this striking feature: "Chrysopilus" means "golden hair" and thoracicus refers to the thorax. The eye-catching spot-of-gold marking is framed by smoky wings with dark veins.

 

 

Little is known about this native fly's life cycle and lifestyle. Its most often observed in the forests of the eastern U.S. and appears to have one generation per season with peak numbers occurring in late May to early June.

 

The "snipe" in the common name is shared by all flies belonging to Rhagionidae family. It's not a large family with only 16 genera worldwide. The adults of most species are predators that use specialized piercing-sucking mouthparts to suck the life out of insect victims; they snipe other insects.

 

However, a predatory lifestyle has never been proven for Chrysopilus thoracicus.  In fact, adults have been observed visiting the flowers of several native plants, including elderberry, fueling the speculation that they are feeding on nectar and/or pollen. Of course, maybe they wash down their meat meals with a little nectar?

 

It is known that the larvae (maggots) live in the soil, but exactly what they do there isn't firmly known. Some observations suggest the maggots consume decaying organic matter while other reports indicate they opportunistically feed as predators on soft-bodied insects. Again, nothing has been proven.

 

The golden-backed snipe fly proves that snipe hunting is not a futile exercise; however, there is much about this fly that remains unknown. Paraphrasing Churchill, it's a riddle, wrapped in a mystery, inside an enigma. Not a bad description for the mythical nocturnal forest creature that shares its common name.

 

Photo: Joe Boggs

As you’re hiking on forest trails in Ohio, look down occasionally and you may spot an emerald-green Six-Spotted Tiger Beetle (Cicindela sexguttata, family Carabidae). The tigers have a curious affinity for zipping around on woodland trails; large numbers can certainly liven up a hike. 

 

 

Both the common and scientific names for six-spotted tiger beetles are very descriptive. "Cicindela" in Latin means "glowworm" and refers to flashes of sunlight bouncing off the beetle's highly reflective surfaces. The specific epithet "sexguttata" joins the Latin for six (as in sextuplets) with the Latin guttata which means spotted, or speckled. The spots on the six-spotted tiger beetle are arranged along the trailing edge of the wing covers, three spots per side.

 

 

Tiger beetles behave exactly like their larger feline namesake. They hunt, kill, and eat their arthropod prey. If you can get close enough, you'll see powerful sickle-shaped mandibles that are used to grab and dispatch luckless arthropod victims. A word of caution: these carnivores can also use their impressive mandibles to deliver a painful bite to the hand of the overly curious.

 

 

Six-spotted tiger beetles appear as temperatures warm in early spring and they remain active until early-to-mid summer. After that, you'd need to dig into forest soils to find the larvae which are also predators. However, instead of actively hunting their prey, they conceal themselves in vertical burrows in the soil to await hapless victims. When a meat item such as insects or spiders walks past, the tiger larva springs forth like a jack-in-the-box to grab dinner with their powerful mandibles.

 

The bottom line is that six-spotted tiger beetles are highly effective and important predators throughout their life cycle. So, keep your eyes peeled for and hands away from these tiny tigers prowling our woodland trails.

Canada Thistle (Cirsium arvense) is not Canadian. It’s native to southeastern Europe. Exactly how it got to North America is not known but our friends up north got blamed even though there’s evidence it arrived in the U.S. and Canada at around the same time. Thankfully, Ohioans weren’t involved in the name game; it could have been called “Michigan thistle.”

 

 

Canada thistle remains a stubborn invasive weed despite having so many things working against it from ghostly bleached-out foliage to holey leaves to flower heads invaded by a weevil. Why is this? The answer, my friend, is blowin' in the wind.

 

Canada thistle can reproduce and spread via underground stems called rhizomes; however, it’s also a prolific seed producer. Various online university and government-based resources report that seed production ranges from around 1,500 to over 5,000 seeds per plant with seeds remaining viable for over 20 years. So, thistle's ability to re-seed can overcome just about any thistle calamity.

 

 

 

 

 

Ghosts in the Mist

The bacterium Pseudomonas syringae pv. tagetis (PST) is causing the tops of infected plants in southwest Ohio to look like they were dipped in bleach.  PST produces a chemical called tagetitoxin which is an RNA polymerase III inhibitor that blocks the production of chloroplasts.

 

 

PST infections will not only produce chlorotic stems and foliage, but they will also reduce seedhead production and can occasionally cause plant mortality. The bacterium received a great deal of research attention in the early 2000s as a possible biocontrol agent for Canada thistle.

 

 

Unfortunately, PST has defied being cultured in a laboratory; all testing thus far has been done using extracts from infected plants. Also, even though flower head production was reduced by as much as 87% in research trials, Canada thistle is such a prolific seed producer researchers concluded that PST would not be able to overcome re-seeding by surviving plants.

 

 

Photo: Joe Boggs

Holey Thistles

The annual holey-handiwork of the Thistle Tortoise Beetle (Cassida rubiginosa, family Chrysomelidae) is also appearing on Canada thistle plant in southwest Ohio. Both the adults and larvae chew multiple holes in leaves to produce see-through leaves. 

 

 

The beetles are pale green or yellowish-green which allows them to blend with their host's leaves. Like other tortoise beetles, the adults have a body shaped like a flattened pith helmet. The head and legs of the adults are typically hidden under the flares of their helmet-like bodies. The antennae can be hidden or extended out from underneath the front of the beetle.

 

 

The oval-shaped larvae have a ring of spines arranged crown-like around the edge of their bodies. The larvae sport a pair of spike-like appendages (cerci) at the tip of their abdomen which they use to spear and carry an odious collection of feces and shed exoskeletons in an umbrella-like fashion over their bodies, presumably for protection against predators.

 

 

 

This weed-whacking beetle was intentionally imported from Europe and northern Asia into North America as a biological control for thistle. The beetle is also known as the "thistle defoliating beetle" and it feeds on other non-native thistle-nasties including musk thistle (Carduus nutans) and plumeless thistle (Carduus acanthoides) thistles. Unfortunately, the efforts of the beetles to eliminate Canada thistle are commonly thwarted by the weed’s reproductive capacity.

 

 

A Thistle Headache

I recently took pictures of another non-native beetle imported into the U.S. in an effort put the kibosh on non-native thistles. The so-called Thistle Head Weevil (Rhinocyllus conicus, family Curculionidae) is native to southern and central Europe, North Africa, and western Asia. It was first released in Canada in 1968 (uh-oh!) followed by releases in several U.S. states in 1969. The primary target was musk thistle, but it also has a liking for Canada thistle.

 

 

The females lay eggs in the bracts of thistle flower buds and the resulting weevil larvae bore into the flower head where they feed on the flower parts. The damage stimulates thistles to produce a gall-like structure that surrounds the weevil larvae and provides more weevil fodder.

 

The initial results after the first round of weevils were released looked promising with musk thistle stands reduced by 80 – 90% where the weevils became established. The data was used to justify more weevil releases in North America.

 

 

Unfortunately, it was eventually discovered that the thistle head weevil had taken a fancy to a wide range of native thistles including some species that were already rare and struggling. We commonly lump thistles into the “malevolent weed” category; however, our native thistles provide significant ecological services. Their loss would impact birds to bees. The saga of Rhinocyllus conicus in the North America has become a cautionary tale illustrating the possible unintended consequences of releasing non-native enemies of non-native invasive plants no matter how noble the cause.  

 

 

On a final note, the weevil does not have an Entomological Society of America (ESA) approved common name. “Thistle Head Weevil” is just one of several names applied to the weevil. This means anyone can propose a common name. Given that the weevil was first introduced into Canada …

Photo: Joe Boggs


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