For example, species of Taphrina seen on the ostrich fern, the common tormentil, or the downy birch. For example, nematodes in hares and rabbits. In extreme conditions, certain species of waterbears. Head or body lice which, according to Heraclitus,  were fateful for Homer: small boys killing off lice deceived him by saying: 'What we see and catch we leave behind; what we neither see nor catch, we carry away.'"
If Homer is the first poet and Heraclitus the first philosopher, the original written or historical tie between these two experiences of language and being is formed by a parasite. An invisible and non-human internal enemy creates a bridge between poetry and thinking by making the death of a poet and its corporeality the object of Heraclitus' thinking. (Perhaps the 'invisible bond stronger than the visible' in Heraclitus signifies the persistence of a parasite.)
The Greek para-sitos (para: at or to one side of, beside, side by side, sitos: grain, wheat, food) eats the same wheaten bread as its host. This is one form of parasitism: eating the same grain or food so that the host gets less than was intended. But in addition to parasitism on the same grain there exists the "parasitism on a different grain", where the parasite waits until the host has eaten the grain and then feeds on him. A different-grain parasite knows how to use its host to adapt the world to its own purposes. Let the host cultivate and consume the grain as successfully as possible, in order to be as succulent as possible.
An example are people without land or property who are housed by their employers and work for their board -- itinerant agricultural labourers, who were actually called 'parasites' in some regions of Scandinavia.
Such a parasite lived in the house of another and paid for his or her lodgings by either money or work; all they owned was themselves.
In agrarian Scandinavia the class of people termed parasites were related to beggars and were sometimes considered identical with them. Just as biological endoparasites, the "parasites" at a farm did not remain outside, but were organic and essential parts of the household, as endoparasites would be of the human body. These social outcasts or their families did not necessarily own one single thing. They were outside the social class system and the then society, despite residing at its core. In towns, their counterpart was the rabble proletariat, Marx's Lumpenproletariat.
In all their misery, in their unremitting idleness and absolute marginalisation, these not-quite-humans are an accurate image of a position which it would be meaningful for experiential language to try to colonise more persistently than so far -- if, that is, it wants to separate itself from the structurally élitist vanguard position of historical avant-garde.
As a prefix, 'para-' can infest several words, almost always distorting the meaning of its host word to something different, though rarely to its direct opposite: paradigm, para-dox, para-site. 'Para-' bends the meaning but does not break it: it is not a negation, and that is why its dialectic is residual, unexpected and asymmetrical.
'Paralanguage' is a part of the materiality of language, which anticipates, exceeds, overflows, confuses and suggests -- rhythm, accent, filler sounds. In the materiality of language, paralanguage is the most vague, ego-less, unique and untranslatable part. At the same time, this materiality stoops to slips of the tongue, reveals tensions and premonitions of body and mind. The parasite of speech inhabits its living tissue. The corpus of language needs, yearns for and hates its parasites. They only feel at home in unrefined and mixed language. 
'Para-' could be a life-size rupture in the mutilated existence that is travelling from one storage site to the next (from natural resources to the dump), a rupture that causes matter and energy to circulate and breathe. The garbage chutes of supermarkets contain an inexhaustible supply of edible food almost every day of the week.
The gift of the parasites is radical variation; they modify the genetics of their host bodies by forcing them to mutations, exceptions and surprises. These metamorphoses may be lethal, but never unnatural. The nature of parasites cannot be returned to survival. By finding unexpected places to settle on, they test their own viability as well as the limits of their host bodies.
The process of mutation supports experimental biology. The experimental must allow itself to be experimented on by admitting that it is in the process of becoming something that it does not know. By admitting this -- in the midst of everything, permeated by the ordinary and surrounded by the typical.
A parasite is a mascot animal for materialism, of which a narrowly understood, scientific physics and idealistic human-centeredness have been weeded out. It is a form of life of a language which no longer gives priority to the busyness of denotations, to communicative reason and the usefulness of words. Instead, it is mutterings and slips of the tongue, pre-conceptual lack of intentionality, rude grunt. Let language descend into its night and rest in that which has no words. Let it be composted, eaten in the dark, transformed into soil. Let it be decomposed into something else.
The unconscious in language that encounters an experience like this does not reside in the individual or in the inter-individual. Its place is in soil circulation, with nameless forms of life. Parasites favour this soil and are of it, they are living parts of the soil.
The skill of the parasites is to live in the inalienably experiential nowhere, for nothing, from nothing. A parasite has no foundation or guarantee, but precisely because of that it has the bareness of its existence. Between liberal irony and cynical neo-conservatism, there is a narrow pathway to bare existence and its language, which is based neither on the refining nature of languish nor on mystical bliss: the existence of non-existence is what is there: which might be called itself and nothing else.
Labourer-parasites were the most flexible, submissive and therefore the most usable pre-precarious section of the rural labour force. As seasonal workers forced to be happy with minimum subsistence, they certainly did not leech the landowners; on the contrary, the economy of a large farm leeched their vitality.
Modernity did not change this situation significantly. Now, the productivist planetary economy is a parasite of its parasites, arrogantly hiding its own immortal, nihilistic dependence in the bodies of its destitute as chemical residues, sense of meaninglessness, lifestyle diseases and the increasing loneliness of individuals. Perhaps the most effective way of turning against this industrialised parasitism is to over-identify with it, to feed on the parasite that feeds on us. To begin by refusing the burden that has been placed on individual consciences and cannot be resolved. To begin to be of no use to the host. To become half invisible. To pilfer resiliently and direct all one's strength to forms of life which are alien to the host body and will stealthily grow inside it. ("Has that lump been there long?" "Who planted potatoes under those trees?" "Why are there lights on in the garden shed?")
A parasite is not a groom or slave, it or he/she is not under a service contract. It is threatened with extinction and without a contract. Towards its host, it has a sporadic dialectic. A parasite and its host are not necessarily aware of each other at all, they do not necessarily meet, but they can feel each other when they are -- not in the same body -- but the same body, a co-body divided into two wills.
There are not only different ways of existing. There are different existences. What the parasite calls existence is significantly different from the existence of the host body, and the best evidence of this is the inalienable intertwining of these two existences in the same flesh. The parasite is not attached to its host, or the host to its parasite, by their absolute difference, but by the non-symbiotic and yet indivisible connection between their orders of life. The parasite absorbs vitality only from the perspective of the restricted economy of the host body. Understood in a transindividual and deep-ecological way, it absorbs transsubstantiated sun consumed and filtered by its host. In terms of its own power, it is nothing but life-as-a-being that asks so little that, with good reason, everything belongs to it.
The parasite and the host body are never in a symmetrical relationship; they are both pushed to an underdog position and are residual to the lives of each other. This being so, a parasite does not strive towards anything, it cannot rise higher in the food chain. It strives to live. And if, by living, it kills its host, that simply happens.
Where the parasite of nothing lives life pure and simple, then a hyper-parasite, a parasitoid of nature and a powerful class of parasites (eg. demanding consumer) lives the death of its peers and nature. Sometimes it may be difficult to distinguish between these two, because these days it is becoming increasingly difficult to distinguish between lifestyle diseases and lifestyles. However, the decisive battle between one life and another does not take place between the host and the parasite, but between the parasite and the epiparasite. You can learn to distinguish between these two by the fact that an epiparasite tries to convince you of its independence and individuality. In contrast, a parasite admits that it has no opposite or natural enemy, but precisely for that reason it must attach itself with all its might.
If we are wise and capable enough to make this distinction, it may later turn out that the principles and conditions of a parasitic economy are more durable, life-like and natural than the extremely complex and meaning-hygienic edifice of the host economy. In fact, the birth-through-death of the Alien films is iconic because it is possible to discern in it a superior, non-human strategy to destroy all organisational principles and closed systems.
The most natural thing in nature is its basic brokenness, its Ur-conflicting character, its non-symbiotic harmony or undisturbed balance. This continual and creative conflict is well described by the multiplicity of parasitic phenomena. This does not necessarily have anything to do with evolution or, more especially, the 'survival of the fittest', and parasitic phenomena are a good example. Instead of saying that a being is attempting to survive or procreate, the same evolutive arguments may be used to claim that it simply wants to live and multiply itself or be destroyed and destroy. Therefore, even though a parasite does not in itself have a purpose or a meaning, it may be understood as the vanishing point of the vital power, but in contrast to disease, it does not remove power from circulation, but returns it there. Exceptional courage: always being in the position of underdog, living of it but never giving in.
In the same way, a parasite never rises up in opposition, but adheres with its whole life to something that is alien to it. If a parasite had anything to say, it might be this: the only true revolution is a revolution of life, and the only true revolution of life is made from the inside, with patient suddenness in the flesh of the experience of night.
To be a parasite is to hide oneself in the corners of the centre, in the nooks of the house, in the scalp, as a prefix to a word. No more fleeing to the periphery, positioning in the prescribed margin, but persistent sticking to an inner enmity, an open conspiracy.
Let thinking form a union with the non-human invisible and bare life, or let it be eaten up.
And so they laid their eggs in the eyes of the monster.
 Kahn, Charles K. The Art and Thought of Heraclitus: An Edition of the Fragments with Translation and Commentary. Cambridge: Cambridge University Press 111-112.
 Paralanguage comes under the discipline of paralinguistics. It includes all nonlinguistic vocal expression, including such things as laughter, intonation and crying.