5E: Monstrous Arthropods for Fifth Edition

[Cleon]

is fine without parentheses (which are often redundant)

Yeah, I've vacillated again and now prefer it with the commas.

Will change it in the next update, which'll happen once my first draft of a Description is finished.

Also realized the parenthesized version was slightly ungrammatical and works better as "On a failure, the target cannot use Dodging Flight or Evasive Flight (or a similar defensive ability) to avoid attacks by the giant odonatid until the start of its next turn."

EDIT: Besides, all those parentheses make for a very cluttered paragraph. It was giving me flashbacks to programming in LISP (aka Lots of Irritating Silly Parentheses).

 

[Cleon]

Okay, how's this for a Description?

A giant dragonfly looks identical to its tiny sized cousins except for being about 8 feet long: a long tubular abdomen, a short sturdy thorax with four wings and six spindly legs, and an oval head that's mostly two enormous compound eyes with compact slicing mandibles tucked underneath and a pair of short antennae above. Its body is brilliantly colored in stripes and spots, most often in metallic greens, blues and golds. Dragonflies have translucent, dark-veined wings with a short strip of color on the leading edge near each wingtip (the pterostigmata). The rest of the wing is generally clear and colorless but it may be pigmented. Most normal dragonflies have clear wings, but almost all giant dragonflies have colored wings; the majority are pale amber but some have stripes or patches of color, most commonly russet, scarlet or peacock blue. The most colorful giant dragonfly wings can rival the beauty of a stained glass window.
 Giant dragonfly skin can be transformed into gorgeous leather and is highly prized by some societies for use in magnificent apparel, accessories and decorations. The wings are sometimes used as window panes or fans.
 Aerial Hunters. A dragonfly is an amazingly fast and agile flier, able to move in any direction–including backwards–and can hover as if it's nailed to the air. Their six legs are not built to move quickly on land, but are used for perching and to form a "basket" for catching prey. Natural dragonflies hunt on the wing, preying upon flying insects smaller than themselves. The dragonfly snatches their prey in its leg basket and bites then either devours them in the air or lands on a perch to feed (most often when its meal is inconveniently heavy). The monstrous giant variety preys on creatures up to its own size, and unlike normal dragonflies it will hunt creatures on the ground as well as in the air. The commonest prey are smaller creatures (e.g. a baboon, giant fire beetle, rat, or an unlucky halfling), and it particularly focuses on flying prey (e.g. a bat, eagle or NAME OF GIANT INSECT?).
 Like most giant insects, a giant dragonfly operates entirely on instinct. If the prey looks small and light enough to carry through the air, the giant dragonfly instinctively uses the snatch-and-bite tactic. If the target looks too big and heavy for this tactic, a giant dragonfly repeatedly darts in to bite and then flies out of its victim's reach until it prey falls or the insect receives a significant injury. It automatically flees if approached by any creature bigger than itself, being "programmed" to identify such as potential predators. While a natural dragonfly is exclusively a solitary predator, small groups of giant dragonflies will sometimes attack together and share the kill. This behavior mainly occurs among dragonflies that live in areas with abundant Medium prey. The attacking flight of dragonflies numbers up to a half-dozen or so and does use coordinated tactics like a pack of wolves or lions. Their cooperation is limited to not eating each other.
 Flyers of Lakes and Marshes. Like their normal kin, giant dragonflies congregate over freshwater and spend most of their time hunting for food and breeding. Most giant dragonflies prefer water that's still or slow flowing with abundant aquatic vegetation; typically a lake, pond, marsh or sluggish river. They are only active during the day, sleeping on perches at night. A giant dragonfly often has favorite perches that overlook a good hunting and/or breeding area, which they will defend vigorously from rival dragonflies. Males are way more territorial than females. Dragonflies sometimes fly great distances in search of new bodies of water to claim as their own.
 Like their normal kin, a giant dragonfly larva is an aquatic creature called a nymph or naiad (see Giant Dragonfly Nymph for details). Each species of giant dragonfly can be extremely fussy about what type of water they breed in. The temperature, chemistry, depth, vegetation and current must match the female's exacting standards. The dragonflies mate in midair, often after ferocious aerial jousts between rival males, then the female finds a suitable section of water to deposit her eggs. A female giant dragonfly lays her eggs in multiple clutches, sometimes as few as a couple of eggs at a time, which she will scatter around as many good breeding spots as she can find. Some giant dragonflies will lay eggs in surprisingly small bodies of water that are barely large enough for a single full-grown nymph. If the food supply and other conditions are right, some giant nymphs can mature in a large barrel of water (e.g. a tun barrel of 210 to 252 gallons) or a pool with similar dimensions.
​

 

[Cleon]

and it particularly focuses on flying prey (e.g. a bat, eagle or NAME OF GIANT INSECT?).

I wanted to include a Small flying insect in the list of common prey, but had a ridiculous time finding any.

Most of the Small insects I checked were flightless, and many that I thought would be Small or perhaps even Tiny, like Giant Bluebottles or Giant Mosquitos, were Medium or Large in size.

I gave up after finding one definite and a couple of unsatisfactory maybes:

Firstly: The "Unusually Large Cockroaches" in the Third Edition D&D adventure DD2 Sinister Spire (2007) are sized Small and have a 40 ft. (average) flight speed. What's unusual about them is regular Giant Cockroaches are Medium! DD2 includes Giant Cockroaches and a Cockroach Swarm in the same encounter, so I can't help wondering whether the the "Unusually Large" ones are juveniles and the Giants are their big siblings?

Giant Cockroaches also appear in the 3E Underdark (2003) and in the 4E Dungeon #164 (2009) as part of the Infested Tower encounter in the adventure "Worse than Death" by Robert J. Schwalb.

Secondly: While the 1E AD&D Giant Praying Mantis from Monster Manual II (1983) is Large like the 3E version, the 2E in the Monstrous Manual (1993), the Gargantuan Praying Mantis, is based on the one in SJR2 - Realmspace (1991). While the Monstrous Manual version is just a single-line entry in its "Insect" section, the SJR2 version has a full Monstrous Compendium style writeup which gives them a size of Small to Medium.

Unfortunately, the 2E version is flightless, unlike the 1E and 3E versions. Also, it's literally an Alien Space Insect because SJR2 is a Spelljammer sourcebook!

Third and Finally: Third Edition Dungeons & Dragons has not one, but two varieties of Small maggots, the Dire Maggot from Libris Mortis (2004) and the Giant Maggot from Underdark (2003).

Now maggots are fly larvae, and if the maggot is Small than the fly it pupates into is most likely Small too.

Unfortunately, neither monster specifies what adults these maggots pupate into, and make clear that are Maggots In Name Only that may hatch into other sorts of insect. The dire version describes them as "the worm-shaped larva of a fly, but a dire maggot is the larva of similarly monstrous flying vermin" while the giant one has "larval forms of various giant insects" and "resembles a white or gray worm. Occasionally one has tiny legs that make it look like a pale caterpillar. Some types of maggots are aquatic or amphibious."

So they could be moth or mosquito larva as easily as flies going by that.

Incidentally, the Libris Mortis Dire Maggot is ridiculously nasty: AC 16, Speed 40 ft., climb 40 ft.; HD 6 with advancement to HD 12 while remaining Small, plus a 1d8+2 damage bite with paralyzing venom.

It's the speed I find the most egregious. It's a maggot!

Long story short, now I fancy writing up a Small giant flying insect to have something to list as the Giant Dragonfly's favourite flying meal.

 

[Cleon]

Okay, I've decided to upgrade the Legs capture size to match the size of the Giant Dragonfly since real life dragonflies will hunt flying insect that are almost as big as them.

For proof, see the paper "Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack" by Tharaka Sudesh Priyadarshana from Volume 13 of Threatened Taxa (2021).

I found the paper more easy to read on Research Gate [PDF].

Note the ratio between the mean lengths of an odonate and the smaller odonates they hunt:

Dragonfly vs Dragonfly	Dragonfly vs Damselfly	Damselfly vs Damselfly
46.000mm Dragonfly​	45.749mm Dragonfly​	32.984mm Damselfly​
39.992mm Dragonfly​	32.808mm Damselfly​	28.387mm Damselfly​
0.8694 length ratio​	0.7171 size ratio​	0.8606 size ratio​

So an odonate is willing and able to attack another odonate about 85% of its body length, so I'm allowing the Giant Dragonfly to catch Medium opponents with its Legs, although its Multiattack is still limited to Small targets.

Maybe I should make the Giant Damselfly a Small beast with Hit Points 14 (4d6) and keep it 6 feet long?

The carrying capacity will be an important factor for our giant odonates.

With our current figures, their carrying capacities are:

Small Giant Damselfly	Giant Damselfly	Giant Dragonfly	Imperial Dragonfly	Tropical Damselfly
STR 10​	STR 10​	STR 15​	STR 18​	STR 20​
carry 75 lbs.​	carry 150 lbs.​	carry 225 lbs.​	carry 540 lbs.​	carry 1,200 lbs.​

Let's make up some guesstimates for length/wingspan and weight:

Size​	Damselfly	Dragonfly
Huge​	30/50 ft. 4,500 lb?​	20/35 ft. 4,500 lb?​
Large​	18/30 ft. 1,000 lb?​	12/20 ft. 1,000 lb?​
Medium​	10/18 ft. 175 lb?​	8/12 ft. 250 lb?​
Small​	6/10 ft. 40 lb?​	4½/7 ft. 50 lb?​

At those weights, each size of monstrous Odonatid can catch any smaller Odonatid in the air (as their carrying capacities are higher than the smaller size's estimated body weights), a Giant Dragonfly can catch a Giant Damselfly (as it's light enough to carry) but not another Giant Dragonfly (which is a bit too heavy), but if we extrapolate to a Small Giant Damselfly and Small Giant Dragonfly, they're both strong enough to prey on each other.

Hmm, I think I'd rather fiddle the figures and make the Giant Damselfly around 6 feet long and a bit heavier than the above. Real life tropical giant damselflies are skinnier than the smaller ones, so I feel justified in fiddling the numbers.

Currently thinking of going for:

Giant Damselfly (Small beast) 6 foot long, 10 foot wingspan, weight 50 pounds.
Giant Dragonfly (Medium beast) 8 foot long, 12 foot wingspan, weight 250 pounds.
Giant Emperor Dragonfly (Large beast) 12 foot long, 20 foot wingspan, weight 1,000 pounds.
Giant Tropical Damselfly (Huge beast) 30 foot long, 50 foot wingspan, weight 5,000 pounds.

 

[Cleon]

Have revised the Description slightly and added a Damselfly underbar, then added the result to the Giant Dragonfly Working Draft as follows:

Description

A giant dragonfly looks identical to its tiny sized cousins except for being about 8 feet long and 250 pounds, with a 12 foot wingspan. It has a long tubular abdomen, a short sturdy thorax with four wings and six spindly legs, and an oval head that's mostly two enormous compound eyes with compact slicing mandibles tucked underneath and a pair of short antennae on its brow. The body is brilliantly colored in stripes and spots, most often in metallic greens, blues and golds. Dragonflies have translucent, dark-veined wings with a short strip of color on the leading edge near each wingtip (the pterostigmata). The rest of the wing is generally clear and colorless but it may be pigmented. Most normal dragonflies have clear wings, but almost all giant dragonflies have colored wings; the majority are uniform pale amber but some have stripes or patches of bright color, most commonly russet, scarlet or peacock blue. The most colorful giant dragonfly's wings rival the beauty of a stained glass window.
 Giant dragonfly skin can be transformed into gorgeous leather and is prized by some societies for use in apparel, accessories and decorations. The wings are sometimes used as window panes or fans.
 Aerial Hunters. A dragonfly is an amazingly fast and agile flier, able to move in any direction–including backwards–and can hover as if it's nailed to the air. Their six legs are not built to move quickly on land, but are used for perching and to form a "basket" for catching prey. Natural dragonflies hunt on the wing, preying upon flying insects smaller than themselves. The dragonfly snatches their prey in its leg basket and bites then either devours them in the air or lands on a perch to feed (most often when its meal is inconveniently heavy). The monstrous giant variety preys on creatures up to its own size, and unlike normal dragonflies it will hunt creatures on the ground as well as in the air. The commonest prey are smaller creatures (e.g. a baboon, giant fire beetle, rat, or an unlucky halfling), and it particularly focuses on flying prey (e.g. a bat, eagle or giant grasshopper).
 Like most giant insects, a giant dragonfly operates entirely on instinct. If the prey looks small and light enough to carry through the air, the giant dragonfly instinctively uses the snatch-and-bite tactic. If the target looks too big and heavy for this tactic, a giant dragonfly repeatedly darts in to bite and then flies out of its victim's reach until it prey falls or the insect receives a significant injury. It automatically flees if approached by any creature bigger than itself, being "programmed" to identify such as potential predators. While a natural dragonfly is exclusively a solitary predator, small groups of giant dragonflies will sometimes attack together and share the kill. This behavior mainly occurs among dragonflies that live in areas with abundant Medium prey. The attacking flight of dragonflies numbers up to a half-dozen or so and does use coordinated tactics like a pack of wolves or lions. Their cooperation is limited to not eating each other.
 Flyers of Lakes and Marshes. Like their normal kin, giant dragonflies congregate over freshwater and spend most of their time hunting for food and breeding. Most giant dragonflies prefer water that's still or slow flowing with abundant aquatic vegetation; typically a lake, pond, marsh or sluggish river. They are only active during the day, sleeping on perches at night. A giant dragonfly often has favorite perches that overlook a good hunting and/or breeding area, which they will defend vigorously from rival dragonflies. Males are way more territorial than females. Dragonflies sometimes fly great distances in search of new bodies of water to claim as their own.
 Like their normal kin, a giant dragonfly larva is an aquatic creature called a nymph or naiad (see Giant Dragonfly Nymph for details). Each species of giant dragonfly can be extremely fussy about what type of water they breed in. The temperature, chemistry, depth, vegetation and current must match the female's exacting standards. The dragonflies mate in midair, often after ferocious aerial jousts between rival males, then the female finds a suitable section of water to deposit her eggs. A female giant dragonfly lays her eggs in multiple clutches, sometimes as few as a couple of eggs at a time, which she will scatter around as many good breeding spots as she can find. Some giant dragonflies will lay eggs in surprisingly small bodies of water that are barely large enough for a single full-grown nymph. If the food supply and other conditions are right, some giant nymphs can mature in a large barrel of water (e.g. a tun barrel of 210 to 252 gallons) or a pool with similar dimensions.

VARIANT: BIG GIANT DAMSELFLY
While a standard giant damselfly is a Small beast some tropical species grow much bigger (see Giant Damselfly for details). A Medium giant damselfly uses a giant dragonfly's statistics but averages 10 feet in length, with a wingspan of roughly 16 to 18 feet. Their nymphs are also as big and dangerous as a giant dragonfly nymph.

I think that'll do.

In the end I used the Giant Grasshopper as the flying insect prey item. It may still be a Working Draft, but the conversion is basically finished and is just waiting for the D&D Beyond version to work.

 

[Cleon]

Just revised the Giant Damselfly to Small and added a Description I'd whipped up.

Odonatid, Giant (Giant Damselfly)
Small beast, unaligned
Armor Class 14
Hit Points 14 (4d6)

Description

A giant damselfly resembles its relative the giant dragonfly (see Giant Dragonfly for details), but is smaller and more slender, with an abdomen that's proportionally longer and thinner and eyes that cover less of the face. The two insects are easy to distinguish when perched, for a damselfly folds its wings back vertically above its body when resting while a dragonfly spreads its wings wide and holds them flat. A standard giant damselfly is about 6 feet long, has a 10 foot wingspan, and weighs 50 pounds; shorter and much lighter than an average giant dragonfly. However, a few species of giant damselfly are much bigger and have statistics that compare to a giant dragonfly or imperial giant dragonfly and the largest, the tropical giant damselfly, is so enormous they dwarf all other giant odonatids (see Giant Dragonfly, Imperial Giant Dragonfly and Tropical Giant Damselfly for details).
 Flying Predators. Giant damselflies are generally similar to dragonflies in habits. Unlike giant dragonflies, most giant damselfly take after their normal-sized relatives and only hunt in the air, so pose little threat to creatures on the ground even if they're small and weak enough to be easy prey. A giant damselfly will eat any flying creature it can catch, most often Tiny creatures such as bats, birds (including hawks, owls and ravens), flying snakes or giant fruit flies. Some areas welcome giant damselflies because they eat serious pests such as stirges and giant mosquitoes, which are also a favorite food for giant damselfly nymphs (see Giant Mosquito for details).
 Shimmers of Damselflies. Giant damselflies tend to prefer faster-flowing water than dragonflies, although there is great variation between species with some that thrive in stagnant or brackish water and even one whose young live in seawater. Like dragonfly larvae, damselfly nymphs are voracious aquatic predators (see Giant Damselfly Nymph for details).

VARIANT: SMALL GIANT DRAGONFLY
Some varieties of giant dragonfly are the same size as an average giant damselfly, although most are longer and far heavier. A giant dragonfly of Small size would use a giant damselfly's statistics but be 4½ feet long, with a wingspan or around 7 feet.

EDIT:Just noticed that I had pasted VARIANT: BIG GIANT DAMSELFLY in during my edit instead of the VARIANT: SMALL GIANT DRAGONFLY it should have been.

Gaah!

It's fixed now.[/EDIT]

 

[Cleon]

Have revised the Description slightly and added a Damselfly underbar, then added the result to the Giant Dragonfly Working Draft as follows:


I think that'll do.

In the end I used the Giant Grasshopper as the flying insect prey item. It may still be a Working Draft, but the conversion is basically finished and is just waiting for the D&D Beyond version to work.

Upon reflection, I prefer "7 or 8 feet" for the length.

Updated the Giant Dragonfly Working Draft.

 

[Cleon]

Okay, fixed a couple of very minor typos in the Giant Dragonfly and Giant Damselfly, namely a "Giant Giant", an "average" that should be "averages" and a superfluous "sized".

Updating the Imperial Giant Dragonfly with the following:

Description

Apart from its size an imperial giant dragonfly is little different from a standard giant dragonfly. These insects are about 12 feet long and 1,000 pounds, with a 20 foot wingspan. Many species live in hot climates, but quite a few prefer temperate climes.
 Lions of the Sky. Imperial giant dragonflies are aggressive aerial predators who preferentially target Small and Medium flying creatures, particularly monstrous insects such as giant grasshoppers, giant wasps, and smaller giant odonates. Their fondness for eating regular giant damselflies and giant dragonflies probably explains why those are rare around the tropical rivers and lakes where the imperials thrive. Imperial giant dragonflies inhabiting the tropics tend to be extremely colorful, and the swirling brilliant of a flight of these odonatids has earned them the collective name "a kaleidoscope of dragonflies."

VARIANT: IMPERIAL GIANT DAMSELFLY
While a standard giant damselfly is a Small beast some tropical species grow much bigger (see Giant Damselfly for details). A Large giant damselfly uses an imperial giant dragonfly's statistics and averages 18 feet long, with a 30 foot wingspan. Their nymphs are as dangerous as an imperial giant dragonfly nymph.
​

That just leaves the Tropical Damselfly of the adult Giant Odonatics to finish.

That might take a bit longer, since I keep on coming up with ideas for it.

EDIT: Going by some tropical giant damselfly proportions, an 18-footer Imperial Damsel has shorter wings than implied above, so I'm reducing the span from 30 to 24 feet.

Might reduce the wingspans of the other damselflies too.

 

[Casimir Liber]

I have no problem with bitey munchey larvae - they could do significant munching damage. All other stuff looks good.

 

[Cleon]

EDIT: Going by some tropical giant damselfly proportions, an 18-footer Imperial Damsel has shorter wings than implied above, so I'm reducing the span from 30 to 24 feet.

Might reduce the wingspans of the other damselflies too.

Okay, I've been checking my proportions and I've definitely got some of the wingspans off.

The damselflies tend to have proportionally shorter wings than dragonflies as their abdomens are so elongated, and some tropical damselflies have even thinner bodies in proportion to their length.

Obviously there's a great deal of variation from species to species.

The beautiful demoiselle Calopteryx virgo is a decent model for my Giant Damselfly. The latter are 49–54mm long with 31–37mm hindwings, which ought to give it a wingspan of perhaps 65–77mm [ratio 1.327–1.426].

The swift forktail damselfly Ischnura_erratica has proportionally shorter wings, being 30–35mm long with a 35–40mm wingspan [ratio 1.116–1.143].

The Persian damselfly Ischnura intermedia is 27–30mm long but its wings only span 18mm [ratio 0.6–0.666].

The most extreme examples I could find were the blue-winged helicopter damselfly Megaloprepus caerulatus, which has the longest wings of any known odonatid and maxes out at 130mm long with a 190mm wingspan [ratio 1:46](I also found measurements of a specimen 115mm long with a 173mm wingspan [ratio 1.504) and Mecistogaster lucretia which has the longest body, reaching 150mm with a 125mm wingspan [ratio 0.833].

Remember, Megaloprepus caerulatus served as the inspiration for my Tropical Giant Damselfly.

Dragonflies tend to be built stockier than damselflies so often have higher wing-to-body ratios and/or broader wings to support their weight. The most extreme cases I could find were the giant petaltail Petalura ingentissima, which may be the largest overall, 125mm long and 158–162mm [ratio 1.296–1.264]; the heaviest might be the gigantic riverhawker Tetracanthagyna plagiata which gets up to about 100mm length and 163mm wingspan [ratio 1.63], while the one with the greatest wing area might be Petalura ingentissima, which has been measured at 101mm long with a ~130mm wingspan [ratio 1,287] and a maximum wing breadth up to 34 mm.

Going by those figures, I've been setting the body-to-wing ratios of my Odonatids too high.

It also occurs to me that it might make more sense to give the variants the same or similar wingspans as the base odonate since they have the same power and weight, presumably they would need similar sized wings to support them assuming the wing loading and wing proportions are similar.

Also, the biggest dragonflies may be shorter than the biggest damselflies but they're considerably heavier and more powerfully built.

If a giant tropical damselfly is 4,000 pounds as a Huge monster, a Huge dragonfly might scale to be about 6,000 pounds and would likely have STR 22 or higher.

Might stat up a separate "Tropical Titanic Dragonfly" to represent them.