I think I found the answer myself. As has been suggested, the Xenomorph life cycle is loosely based on the life cycles of parasitoid insects.
When Dan O’Bannon started conceptualising his alien creature he turned to two key influences: the creatures depicted in the comic books he devoured as a child, and the insect world. “Works of fiction weren’t my only sources,” he explained in his essay Something Perfectly Disgusting. “I also patterned the Alien’s life cycle on real-life parasites … Parasitic wasps treat caterpillars in an altogether revolting manner, the study of which I commend to anyone who is tired of having good dreams.”...
The insect world, O’Bannon knew, was one of sheer brutality, where even acts of copulation routinely result in murder. ...Insects are also notoriously cruel to other species of insect – the relationship between flies and spiders is an obvious horror, but varieties of wasp also use the bodies of other insects as the host for their young. A genus of the Phoridae fly, the Pseudacteon, also known as the ant decapitating fly, is infamous for its violent use of ant bodies: eggs are laid in the ant’s thorax, and the larvae migrates to the brain, where it feeds on the hemolymph and muscle and nerve tissue. “After about two to four weeks, they cause the ant’s head to fall off by releasing an enzyme that dissolves the membrane attaching the ant’s head to its body. The fly pupates in the detached head capsule, requiring a further two weeks before emerging.”
"It was our idea,” explained Ron Shusett to Cinefantastique, “that it would be the life-cycle of an insect. The way a wasp will sting a spider, paralyze it, and lay its eggs in the spider. Its eggs grow off the living spider, like a surrogate mother. That we did want it to be.”
Ridley Scott added: “There’s a fundamental connection in nature because we actually watched, in preparation for this [movie], Oxford Scientific, [which] had this interesting piece of footage where they’d watched a slice of bark, and there’s a grub underneath the bark … Across the top of the bark was this insect, which passes over the grub, stops, backs up, and ‘feels’ the grub is there, let’s say, the equivalent of 8 feet below you. It goes up on its hind legs, produces a needle from between its legs, and drills through the bark and bulls-eyes right into the grub and lays its seed, so that the grub becomes the host of the insect.”
At first, O’Bannon was stuck on the point of getting the Alien on board the spaceship. Having it simply sneak aboard seemed too banal. But if the creature could stow away within the body of a space-man… Dan, fascinated and repulsed by the horrific life cycle of parasitoid wasps, incorporated the concept into his alien monster. It would gestate inside a living host and explode from their body. The Alien could get on the ship, and excitingly, not without spilling blood.
“The Alien franchise bases its Xenomorph life cycle on parasitic wasps on Earth,” Terry Johnson, a bio-engineering researcher at the University of California, told Popular Mechanics. “It’s a pleasure to see a film that acknowledges just how weird life can be.” But despite the blatant insectile nature of the Alien (specifically its four-staged life cycle and cocooning) and despite O’Bannon, Ron Cobb, Ron Shusett, HR Giger, and Ridley Scott being clear on the issue, fans have been reluctant to admit the insect influence on the original creature, instead brushing it off as an addition made by James Cameron in the 1986 sequel. However, in light of the evidence pointing to the original Alien makers being heavily and happily influenced by insects, attributing this to Cameron is akin to blaming wet streets for rain.
The connection between the Alien and insect reproductive cycles was so crucial that O’Bannon identified it as of “core psychological significance” before quoting biology and science journalist Carl Zimmer: “when an alien bursts out of a movie actor’s chest … it is nature itself that is bursting through, and it terrifies us.”
“I modelled [the Alien] after microscopic parasites that moved from one animal to the next and have complex life-cycles,” Dan explained. “I just enlarged the parasite. I was interested in the biology of aliens, so I wasn’t interested in streamlining the thing below interest level just for the sake of economy.” Ron Shusett, Alien‘s executive producer and friend to O’Bannon, told Cinefantastique: “It was our idea that it would be the life cycle of an insect. The way a wasp will sting a spider, paralyse it, and lay its eggs in the spider … that we did want it to be …. We thought people might pick up on it and say, ‘yeah, an alien life cycle can be an insect life cycle.'”
Alien and Aliens conceptual artist Ron Cobb further explained the origins of the chestburster scene: “He got that from the paralysing wasp … it paralyses the spider and lays its eggs on the spider, then buries it in the ground so that the living spider serves as food for the wasp larva and you know, he always was so horrified at that idea.”
In the 1999 DVD commentary, Ridley Scott explains: “The whole notion of this [creature] was taken off a certain kind of insect that will find a host, lay its eggs, and then in that host it will bury its eggs, and then of course the eggs will grow and consume the host. So that’s the logic of it all. Probably what makes a lot of nature go around.”
“I wanted him [the Alien] to be insect-like. Like an ant. Because if you examine an ant under a microscope they’re kind of elegant, and I wanted him to be very elegant and dangerous.”
- Ridley Scott, The Alien Saga, 2002 (archival interview from 1991)
“We decided to make a very elegant creature: quick, and like an insect.”
- HR Giger, Cinefex, 1979.
Egg silo by HR Giger, embedded into the underbelly of the derelict spacecraft like, in Giger’s words, a termite nest. Originally, the eggs were to be housed inside a pyramid structure, but budget and time forced the filmmakers to economise. “[W]e had to combine the derelict ship and the hatchery silo,” said Giger. “I thought we could place the egg silo under the ship, a bit like termites do.” He concluded, “we decided it would be a good idea to have these eggs inside the derelict like termites inside the walls of a house.” Image copyright HR Giger.
To sum up the insectile traits of the Alien:
-The parasitic life cycle: The Alien is a parasitoid, needing a host in order to reproduce, like parasitic wasps. Ron Cobb identified the paralysing wasp as influencing O’Bannon. These wasps paralyse potential hosts and implant their seed along with a virus that suppresses the immune system which allows the larvae to grow undetected by the host. The large, formidable looking ovipositor of the Ichneumon wasp is not used to sting and wound, but to sting and impregnate.
The Alien can be more accurately described as a protolean being, defined by Wikipedia as creatures “that begin the growing phase of their lives as parasites, and in particular, typically as internal parasites. As a rule they end that phase of their lives parasitoidally by killing or consuming the host, and then they emerge as free-living adults.”
-Larval, pupal, and adult life-stages: From the egg comes the facehugger, the first stage of the Alien life-cycle. The facehugger’s function is to locate, subdue, and impregnate a host via its proboscis. The impregnated host is the pupae stage. Once the Alien violently emerges from the host it must shed its skin and grow in order to become an adult. Butterflies go through a growing process known as Complete Metamorphosis – meaning its adult stage is completely different to its larval stage, as is the adult Alien from its infanthood as a chestburster. Once the chestburster has shed its skin (as most insects do, usually shedding exoskeletons numerously into adulthood) it leaves behind the instar stage of its life and becomes an adult.
-Cocooning: The Cicada Killer Wasp cocoons its prey near the eggs of its young so that the newly hatched wasps have a food source. In Alien, the Alien cocoons Dallas and Brett not to feed on them, but for reproduction (though in early scripts, the Alien did eat parts of its cocooned hosts – it even ate Lambert whole in one version.) In Aliens, the colonists are abducted, subdued, and embedded into the walls of the hive to await death. In scripted, but unfilmed, portions of Alien 3, the prisoners were to come across the Alien’s nest, where they discover a cocooned Superintendent Andrews along with other half-eaten bodies. The characters identify the nest as a “meat locker”, presumably where the Alien stores hosts and food for its inbound Queen.
All of these elements bar the cocooning were present in the theatrical release of Alien. We see the Alien progress through the various stages of its life, getting a glimpse of some shedded skin along the way and even hints of the creature’s limited lifespan – “I wanted a sense of a timeless, slightly decaying creature that, maybe, only has a limited life cycle of, maybe, four days like an insect,” said Ridley Scott, adding: “the Alien lifeform lived to reproduce … [Ripley] killed it, but it would have died soon anyway. It’s like a butterfly.”
Insectile additions to the Alien life-cycle in the sequel:
-The hive: like ants and most wasps (not all are eusocial), the Aliens adopt a functionalist, hierarchical social system. Contrary to popular belief, this does not consist of drones and warriors. Cameron scripted Alien drones in his 1983 treatment but cut them in the next draft. When JamesCameronOnline asked John Rosengrant if the drones even reached any preliminary design stages, he answered: “Not really, as far as I remember.” Cameron himself explained that the term ‘Alien Warrior’ was not to denote two different kinds of Alien (as is often mistaken) but was merely “my term for the single adult seen in Alien.” The expanded universe and fanon generated the idea that domed and ribbed head Aliens represent two different castes, but this has no basis in the release version of Aliens and perhaps belongs and owes its popularisation more to the comic books and games.
-The Alien Queen: The Alien society within the hive consists of adult Aliens and their mother, the Queen. Unlike ants or termites, the Alien Queen does not have a need for a male counterpart (ants employ drones, and termites have kings to impregnate the queen). Like the creature in Alien, the Queen is ambi-sextrous, a hermaphrodite, capable of reproducing without the seed of a male. “There are insects like that [androgynous, asexual]” Ridley Scott said of his Alien, “so we based that on a little bit of good old Mother Nature.” The original creature was at first envisioned as a female, before becoming thought of as a hermaphrodite by Scott once Bolaji Badejo was cast (initial efforts to cast a tall, thin woman failed). The Queen likely carries a feminine title (just as the first Alien was dubbed “Kane’s Son”) for clarity and because we tend to struggle without gender-specific labels (though it should be noted that Cameron referred to the Aliens in a male/female capacity – though he also noted that they can change gender if a Queen is present or absent).
It’s usually thought that the insect elements began and ended with Cameron, but in fact not only did they begin with Dan O’Bannon, but they were continued and pursued even by David Fincher for Alien 3.
From the fears and morbid interests of Dan O’Bannon, through Ridley Scott’s research into insects, and Ron Shusset’s declaration that an insect life-cycle was the intention, it cannot be denied that the Alien is an amalgamation of horrific insectoid sexual aesthetics and traits, which contributed not only to the nightmare inducing nature of the creature, be its abilities, its visage, its growth cycle, but to its integrity as a space dwelling avatar of death as well. Strip the monster of all insectile traits and nothing reminiscent of the series’ Alien is left. Alien, Aliens, and Alien 3 managed to equilibrate the sexual and insectile overtones to create a startling, original beast, an equilibrium upset in the expanded universe and spin-offs, which saw a dilution of the creature’s sexual elements and subsequent diminishing returns.
