40 Fun Facts About Dobsonflies and Hellgrammites

Hellgrammites are prized by anglers as bait for which river fish in particular?

Smallmouth bass find the wriggling larvae hard to resist. Yet hellgrammites rarely turn up in fish stomachs, probably because they stay hidden where fish cannot reach them.

The white egg masses of the eastern dobsonfly, each about 2 cm across, are often mistaken for what?

Bird droppings are what the coin-sized masses resemble once their coating dries white. Each one holds about a thousand eggs stacked in three layers.

Locals along Virginia rivers say which weather event triggers mass 'hellgrammite crawlings'?

Thunderstorms are said to set off the exodus, perhaps because the larvae feel the vibrations. Full-grown hellgrammites along a stretch of river all leave within a few days of each other.

In New Zealand, the stream-dwelling larva of the local 'dobsonfly' goes by which alarming nickname?

Toe-biter is the common name for the larva, which Māori call puene. The insect is really a fishfly, the only one in New Zealand, and its young are among the country's biggest freshwater insects.

Why can't a male eastern dobsonfly give a painful bite with tusk-like jaws up to 4 cm long?

They lack leverage because they are so long, so the fearsome-looking male is harmless. The female's short, stout jaws are the ones that can draw blood.

Hellgrammite is also an insect-like supervillain who debuted in 1968 in which publisher's superhero universe?

DC Comics introduced Hellgrammite in The Brave and the Bold, where the mutated entomologist fought Batman. He later became a recurring foe of Superman.

Adult eastern dobsonflies have fearsome jaws, but what is believed to be true of their diet in the wild?

They do not feed in the wild, it is generally believed, running instead on nourishment stored up as larvae. In captivity, though, they will sip honey water.

Finding hellgrammites in a stream is generally taken as a sign of what about the water?

It is clean, or close to it: hellgrammites tend to live only in relatively unpolluted streams. That makes them handy for scientists who monitor river health.

With long, flat bodies and rows of leg-like side filaments, hellgrammites are often likened to what?

Centipedes are the usual comparison, but only six of those limbs are true legs. The eight pairs of side filaments work as feelers that help fend off small attackers.

After years underwater as a hellgrammite, roughly how long does a winged eastern dobsonfly live?

About a week is all the adult gets, and males may last only three days. That brief winged life is devoted entirely to mating and laying eggs.

What does Megaloptera, the Greek-derived name of the insect order that includes dobsonflies, mean?

Large wing is the meaning, from the Greek megas and pteron. For all that wing area, the adults are weak, clumsy fliers.

The order Megaloptera holds just three groups: dobsonflies, fishflies and which smaller, dark-winged relatives?

Alderflies complete the trio and are the little cousins, with bodies under an inch long. Their larvae end in a single tail-like filament, which hellgrammites lack.

The old Appalachian name 'grampus' was shared by dobsonfly larvae and which giant salamander of the same streams?

Hellbender, the largest salamander in North America, was also called a grampus in the southern Appalachians. The origin of the word hellgrammite itself is unknown.

In the dialect of the Ozarks, hellgrammites used as fishing bait go by which colourful name?

Devil scratchers is the Ozark term for the sharp-jawed larvae. An 1883 anglers' journal listed dozens of other local names, among them conniption bugs and molly-grubs.

Males of many fishflies lack a dobsonfly's giant jaws but sport which kind of antennae instead?

Feathery, comb-like antennae are the hallmark of many male fishflies. Dobsonflies and fishflies share one family, and anglers call the aquatic larvae of both hellgrammites.

Which naturalist gave the eastern dobsonfly its first scientific name, back in 1758?

Carl Linnaeus described the eastern dobsonfly, still the best-known member of its genus. Most of the other Corydalus species were named more than a century later.

Where do hellgrammites spend most of their time, which helps explain why fish seldom eat them?

Under rocks is where they hide, usually in the swiftest stretches of a river. Collectors catch them by disturbing the stones just upstream of a net.

Nocturnal adult dobsonflies hide in streamside vegetation by day, but what strongly attracts them after dark?

Bright lights pull the night-flying adults in from nearby streams. Entomologists exploit the habit with black-light and mercury-vapour traps.

In which country are stream insects, dobsonfly larvae among them, sold as an edible souvenir called zazamushi?

Japan is where zazamushi are gathered, along the upper Tenryu River in Nagano. The name also covers the larvae of stoneflies and caddisflies, usually simmered or fried.

Huge, drab and fluttery, adult dobsonflies are often mistaken for which insects that never have pincer jaws?

Moths are the usual mix-up, since both are big, soft-winged and active at night. A resting dobsonfly folds its wings flat over its back, where they reach well past its abdomen.

Besides their underwater breathing organs, hellgrammites have which openings for taking in air directly?

Spiracles let a hellgrammite breathe out of the water as well as in it. That matters at the end of larval life, when it leaves the stream for good to pupate.

During courtship, a male eastern dobsonfly rests his long jaws across which part of the female?

Her wings are where he lays them, at right angles, and he holds the pose until she accepts him. Older accounts wrongly claimed that males gripped the female with their jaws.

Hellgrammites, active mostly at night, catch the young of mayflies and midges using which hunting style?

Ambush is the method: a hellgrammite stays put and seizes whatever the current sweeps past. It ranks among the top invertebrate predators of its stream.

Lacking silk glands, a full-grown hellgrammite pupates inside which kind of shelter?

A cell dug in soil does the job: the larva excavates it with its legs and mouthparts, then smooths the walls with its body. It may walk 15 metres from the stream to find a moist spot.

Inside the pupal skin, a male eastern dobsonfly's long jaws are packed away like which instrument?

Accordion is the image an entomologist used in 1952 for the folded jaws. The packing explains why male and female pupae look much alike although the adults differ so sharply.

What is the type of insect development that takes a dobsonfly through egg, hellgrammite, pupa and adult called?

Complete metamorphosis is the term, though megalopterans have its most rudimentary form. Their young and adults differ less than in any other insect order with a pupal stage.

Unlike most insect pupae, which lie helpless, a dobsonfly pupa can do what if it is disturbed?

Bite an attacker is exactly what it can do: the pupa stays mobile and has working jaws. Its legs and wing buds hang free of the body instead of being sealed in a hard case.

Megalopterans such as dobsonflies were once classed in Neuroptera with snakeflies and which delicate insects?

Lacewings now keep the name Neuroptera for themselves and their kin. The three groups remain close relatives, and their nearest living cousins beyond that include the beetles.

Why do some US states regulate the sale of hellgrammites collected from streams?

They can be overharvested for bait, since the larvae are laborious to collect and fetch high prices. Some anglers use hellgrammite-shaped lures instead.

The world's largest aquatic insect by wingspan, a dobsonfly spanning 21.6 cm, is native to which continent?

Asia is home to the record holder, Acanthacorydalis fruhstorferi. The biggest dobsonflies of its genus have bodies over 10 cm long, and its name honours the entomologist Hans Fruhstorfer.

The long jaws of a male eastern dobsonfly, up to 4 cm, are usually described as shaped like which tool?

A sickle is the standard comparison for the male's curving jaws. He wields them to joust with rival males and in courtship.

Most of the forty or so species of Corydalus dobsonflies are found in which part of the world?

South America holds most of them, with many known only from Venezuela. Just four species, the eastern dobsonfly among them, reach the United States.

The oldest fossils confidently identified as megalopterans, the dobsonfly order, date from which period?

Jurassic deposits from early in that period hold the oldest certain megalopterans. Several older fossil families once assigned to the order are now disputed.

Newly hatched hellgrammites often drift off to find a home in the stream buoyed up by what?

An air bubble often keeps the tiny hatchling afloat until it reaches a swift stretch of the stream. The eggs hatch one to two weeks after they are laid.

The chalky white coating a female dobsonfly brushes over her egg mass helps shield the eggs from what?

Overheating is the threat a 1992 study pointed to. The female applies the coating as a clear fluid with the tip of her abdomen, and it turns white as it dries.

Rival male eastern dobsonflies joust by sliding their long jaws under an opponent to do what?

Flip him over is the aim: each male tries to lever his rival into the air. The winner then approaches a female and touches her with his antennae.

Where are anglers advised to grasp a live hellgrammite so that it cannot bite them?

Behind the head is the safe grip, out of reach of jaws that can give a painful nip. Their toughness and ferocious temperament are part of why anglers rate the larvae so highly.

Female eastern dobsonflies glue their egg masses to which kind of surface near a stream?

Surfaces overhanging the water, such as leaves, branches and bridge abutments, are her choice. The masses cluster in patches, hinting that a scent left by one female draws in others.

In an 1878 report, Mississippi fishermen used the name 'Dobson' for which stage of the dobsonfly?

The larva was the original Dobson, prized by river fishermen, while the winged adult was called the hellgrammite fly. The two names have since traded places.

What do hellgrammites use to hold fast to the stream bed against a swift current?

Hooked hind prolegs do it: each of the two stubby limbs at the tip of the abdomen ends in a pair of hooks that grip the bottom. The fast water they favour would otherwise sweep them away.