Alex Hyde / Human Head Louse (Pediculus humanus capitis) macro shot of claw, that allows the louse to grip onto the hairs of their human host, False-colour scanning electron micrograph (SEM).

Juergen Freund / Pink anemonefish (Amphiprion perideraion) hiding amongst the tentacles of its closed anemone host, Kimbe Bay, West New Britain, Papua New Guinea.

Alex Hyde / Giraffe necked weevil {Trachelophorus giraffa} male on leaf of host plant (Dichaetanthera cordifolia) tropical rainforest, Mantadia NP, Madagascar

Tim Laman / Strangler Fig (Ficus sp.) that has killed its host tree long ago. The host has rotted away, leaving a hollow center. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.

Wild Wonders of Europe / Benvie / Broomrape (Cistanche phelypaea) in flower, killing its host Glasswort (Salicornia sp) Huelva, Andalucia, Spain, April 2009

Hiroya Minakuchi / Pink Anemonefish (Amphiprion perideraion) in Magnificent Sea Anemone (Heteractis magnifica) host tentacles, Celebes Sea

Georgette Douwma / Pink anemonefish (Amphiprion perideraion) in host anemone. Papua New Guinea.

Pete Oxford / Madagascar Moon Moth (Argema mittrei) male on Jamun (Eugenia jambolana) leaves in the eastern highlands south of Antananarivo, Madagascar

Doug Perrine / Pink anemonefish {Amphiprion perideraion} on host sea anemone {Heteractis magnifica} Great Barrier Reef, Queensland, Australia

Fred Bavendam / Pink Anemonefish (Amphiprion perideraion) nestled among the tentacles of its Sea Anemone host, Great Barrier Reef, Queensland, Australia

Chris Newbert / Blackfinned Clownfish (Amphiprion percula) in bleached Magnificent Sea Anemone (Heteractis magnifica) host, Papua New Guinea

Fred Bavendam / Pink Anemonefish (Amphiprion perideraion) nestled among the tentacles of its Sea Anemone host, Coral Sea, Queensland, Australia

PREMAPHOTOS / Pupae of parasitic wasp {Braconidae family} on hawkmoth caterpillar host, Peru, South America

Birgitte Wilms / Pink Anemone fish (Amphiprion perideraion) in host Magnificent Sea Anemone

Birgitte Wilms / Blackfinned Clownfish (Amphiprion percula) in bleached Magnificent Sea Anemone (Heteractis magnifica) host, 30 feet deep, Papua New Guinea

Chris Newbert / Blackfinned Clownfish (Amphiprion percula) pair in Magnificent Sea Anemone (Heteractis magnifica) host, Solomon Islands

Birgitte Wilms / Blackfinned Clownfish (Amphiprion percula) in bleached Sea Anemone host, 30 feet deep, Solomon Islands

Chris Newbert / Blackfinned Clownfish (Amphiprion percula) in a Magnificent Sea Anemone (Heteractis magnifica) host, Solomon Islands

Norbert Wu / Blackfinned Clownfish (Amphiprion percula) pair, safe among stinging tentacles host Magnificent Anemone (Heteractis magnifica), Solomon Islands

Mark Moffett / Ant (Philidris sp) feeding on the oily orange spores of a host fern The ant lives in the fern's stem, where it drags nutrient rich debris to create compost for the fern, Borneo.

Fred Bavendam / Blackfinned Clownfish (Amphiprion percula) in Magnificent Sea Anemone (Heteractis magnifica) tentacles, Great Barrier Reef, Queensland, Australia

Fred Bavendam / Clown Anemonefish (Amphiprion ocellaris) among the tentacles of a Magnificent Sea Anemone (Heteractis magnifica), Bali, Indonesia

Mark Moffett / Ant (Pseudomyrmex sp) tends pupa, while larvae at right, eats carrot-like growth from host Acacia

Mark Moffett / Carpenter Ant (Camponotus schmtzi) on tendril of host Pitcher Plant (Nepenthes bicalcarata), Borneo, Malaysia

Fred Bavendam / Blackfinned Clownfish (Amphiprion percula) guarding eggs laid beside their Magnificent Sea Anemone (Heteractis magnifica) host, Kimbe Bay, Papua New Guinea

Piotr Naskrecki / Fig (Ficus sp) tree strangling host tree, Suriname

Piotr Naskrecki / Biting Midge (Forcipomyia tettigonaris) parasite feeding on Katydid (Cycloptera speculata) hemolymph, Suriname

Piotr Naskrecki / Mantid (Liturgusa sp) female with parasitic nematode that has just emerged from her body, killing her in the process, Suriname

Andy Sands / Sand Wasp (Ammophila pubescens) carrying paralysed caterpillar of Common heath moth (Ematurga atomaria) back to burrow, Surrey, UK, August

Andy Sands / Sand Wasp (Ammophila pubescens) carrying paralysed caterpillar of Common heath moth (Ematurga atomaria) back to burrow, Surrey, UK, August

Andy Sands / Sand Wasp (Ammophila pubescens) stinging caterpillar of Beautiful Yellow Underwing moth (Anarta myrtilli), Surrey, UK, August

Andy Sands / Sand Wasp (Ammophila pubescens) carrying paralysed caterpillar of Beautiful Yellow Underwing moth (Anarta myrtilli) back to burrow, Surrey, UK, August

Andy Sands / Sand Wasp (Ammophila pubescens) carrying paralysed caterpillar of Beautiful Yellow Underwing moth (Anarta myrtilli) back to burrow, Surrey, UK, August

Jabruson / 'Ngoumou' strangler Fig tree (Ficus sp) wrapped around host tree, which it will eventually kill. The latex (Idjoro) is used for killing birds by local people, hunters roll the latex onto sticks which...

Jabruson / 'Ngoumou' strangler Fig tree (Ficus sp) wrapped around host tree, which it will eventually kill. The latex (Idjoro) is used for killing birds by local people, hunters roll the latex onto sticks which...

Andy Sands / Ichneumen wasp (Ichneumen sp.) ovipositing into Bulrush head, probable host Bulrush Wainscot moth, East Sussex, England UK, August

Andy Sands / Ichneumen wasp (Ichneumen sp.) ovipositing into Bulrush head, probable host Bulrush Wainscot moth, East Sussex, England UK, August

Andy Sands / Cuckoo bee (Melecta albifrons) parasite of (Anthophora plumipes) on old wall where host species nests, Hertfordshire, England, UK, April

Andy Sands / Cuckoo bee (Melecta albifrons) parasite of (Anthophora plumipes) on old wall where host species nests, Hertfordshire, England, UK, April

MYN / Seth Patterson / Pale Red Bug (Dysdercus concinnus) nymph on Turk's cap (Malvaviscus drummondii) host plant, Sabal Palm Sanctuary, Lower Rio Grande Valley, Texas, USA, September. meetyourneighbours.net project

MYN / Seth Patterson / Pale Red Bug (Dysdercus concinnus) nymph on Turk's cap (Malvaviscus drummondii) host plant, Sabal Palm Sanctuary, Lower Rio Grande Valley, Texas, USA, September. meetyourneighbours.net project

MYN / Seth Patterson / Pale Red Bug (Dysdercus concinnus) nymph on Turk's cap (Malvaviscus drummondii) host plant, Sabal Palm Sanctuary, Lower Rio Grande Valley, Texas, USA, September. meetyourneighbours.net project

MYN / Seth Patterson / Pale Red Bug (Dysdercus concinnus) nymph on Turk's cap (Malvaviscus drummondii) host plant, Sabal Palm Sanctuary, Lower Rio Grande Valley, Texas, USA, September. meetyourneighbours.net project

MYN / Seth Patterson / Pale Red Bug (Dysdercus concinnus) nymph on Turk's cap (Malvaviscus drummondii) host plant, Sabal Palm Sanctuary, Lower Rio Grande Valley, Texas, USA, September. meetyourneighbours.net project

Alex Hyde / Traditional flower-rich hay meadow including Yellow Rattle (Rhinanthus minor), Buttercup (Ranunculus acris), Red Clover (Trifolium pratense) and host of different grasses. Peak District National Park,...

Alex Hyde / Traditional flower-rich hay meadow including Yellow Rattle (Rhinanthus minor), Buttercup (Ranunculus acris), Red Clover (Trifolium pratense) and host of different grasses. Peak District National Park,...

Colin Varndell / Nettle weevil (Phyllobius pomaceus) on Stinging nettle leaf (Urtica dioica), Dorset, UK May 2012

Alex Mustard / Red clingfish (Arcos rubiginosus) pair blend in with their host, a deepwater sea fan (Iciligorgia nodulifera) East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Piotr Naskrecki / Solom Katydid (Salomona bispinosa) parasitized by horsehair worm, New Britain, Papua New Guinea

Nick Upton / Gall fly / Greater fruit fly (Terellia colon) female on flowerbud of host plant, Greater knapweed (Centaurea scabiosa), chalk grassland, Wiltshire, UK, June.

Nick Upton / Female Ichneumon wasp (Stilbops ruficornis) inserting its ovipositor into Field scabious (Knautia arvensis) flowerhead to parasitise eggs of the longhorn moth (Nemophora metallica) as a moth of this s...

Nick Upton / Gall fly / Greater fruit fly (Terellia colon) male on flowerbud of host plant, Greater knapweed (Centaurea scabiosa), chalk grassland, Wiltshire, UK, June.

Nick Upton / Gall fly / Greater fruit fly (Terellia colon) female extending and flexing long ovipositor after mating in preparation for laying eggs in flowerbud of host plant, Greater knapweed (Centaurea scabiosa)...

Linda Pitkin / 2020VISION / Dahlia anemone (Urticina felina / Tealia felina), on bed of Common brittlestars (Ophiothrix fragilis), St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, August 2011. Did...

Nick Garbutt / Egg case made by a female Giraffe-necked weevil (Trachelophorus giraffa) from the leaf of favourite host tree (Dichaetanthera cordifolia), a single egg is laid inside, Ranomafana National Park, easter...

Nick Garbutt / Egg cases made by a female Giraffe-necked weevil (Trachelophorus giraffa) from the leaf of favourite host tree (Dichaetanthera cordifolia), a single egg is laid inside, Ranomafana National Park, easte...

Nick Garbutt / Egg of Giraffe-necked weevil (Trachelophorus giraffa) laid inside the leaf of favourite host tree (Dichaetanthera cordifolia), Ranomafana National Park, eastern Madagascar, November

Christian Ziegler / Fig (Ficus sp) root pattern on host tree, Barro Colorado Island, Panama

Kevin Schafer / Fig (Ficus sp) parasitizing host tree, Tompotike Peninsula, central Sulawesi, Indonesia

Georgette Douwma / Spinecheek Anemonefish (Premnas biaculeatus) in host anemone in coral (Goniopora sp). Bunaken National Park, North Sulawesi, Indonesia.

Georgette Douwma / Red and Black Anemonefish (Amphiprion melanopus) with bleached host anemone. The tentacles of the anemone are usually a dull brown, but this anemone is bleached and has lost most of its endosymbiotic...

Georgette Douwma / Pink Anemonefish (Amphiprion perideraion) in bleached anemone. Anemone (and coral) bleaching results when the symbiotic zooxanthellae (single-celled algae) are released from the original host coral or...

Nature Production / Pink Anemonefish (Amphiprion perideraion) amongst tentacles of host anemone (Heteractis crispa) Okinawa, Japan

Nature Production / Cuckoo's egg (Cuculus canorus) in Stonechat's nest with three host eggs, Nagano, Japan, June

Nature Production / Cuckoo's egg (Cuculus canorus) in Bunting's nest with three host eggs, Nagano, Japan, June

Nature Production / Lesser Cuckoo's egg (Cuculus poliocephalus) in host nest of Black faced bunting (Emberiza spodocephala), Japan

Nature Production / Cuckoo's egg (Cuculus canorus) in Brown shrike's nest with two host eggs, Nagano, Japan, June

Nature Production / Hodgson's Hawk-cuckoo egg (Cuculus fugax) top left with two host eggs in nest, Nagano, Japan

Nature Production / Common Cuckoo chick (Cuculus canorus) pushing Reed-warbler chick (Acrocephalus sp) out of host nest, Japan

Juergen Freund / Ovulid egg cowrie (Pseudosimnia punctata) on its soft coral host, West New Britain, Papua New Guinea.

Juergen Freund / Sacoglossan sea slug / Sap sucker (Elysia sp) a herbivore that feeds, mates and lays eggs on one type of host algae, Batangas, Philippines

Juergen Freund / Clarke anemonefish (Amphiprion clarkii) eggs on rock near host anemone, Bali, Indonesia.

Juergen Freund / Clarke Anemonefish (Amphiprion clarkii) fanning her eggs beside host anemone, Bali, Indonesia.

Juergen Freund / Spinecheek anemonefish (Premnas biaculeatus) in bleached anemone host, Kimbe Bay, West New Britain, Papua New Guinea.

Juergen Freund / Pink anemonefish (Amphiprion perideraion) hiding amongst the tentacles of its closed anemone host, Kimbe Bay, West New Britain, Papua New Guinea.

Birgitte Wilms / Anemonefish (Amphiprion sp) in host Anemone (Heteractis sp), Papua New Guinea

Juergen Freund / True clownfish / Clown anemonefish (Amphiprion percula) tending their eggs, half-concealed in the tentacles of their host anemone. Misool, Raja Ampat, West Papua, Indonesia.

Juergen Freund / Allied Cowrie (Diminovula culmen) camouflaged on Soft coral host (Dendronephthya sp). Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Spindle cowry (Pellasimnia sp) camouflaged on gorgonian coral host, New Ireland, Papua New Guinea.

Juergen Freund / Allied / false cowry sea snail (Ovulidae) camouflaged on fan coral host, New Ireland, Papua New Guinea.

Daniel Heuclin / Sheep Tick (Ixodes ricinus) embedded in skin. Vector for Lyme disease and tick-borne meningoencephalitis. Poitou, France, October.

Nick Upton / Ivy bee (Colletes hederae) a European solitary mining bee that only reached the UK in 2001 which is now spreading from the south coast to the midlands, heavily dusted with pollen from visiting flower...

GEORGETTE DOUWMA / Pink anemonefish (Amphiprion perideraion) with host anemone, Indonesia, October

Konrad Wothe / Fig (Ficus sp) tree that has killed its host in rainforest, Daintree National Park, North Queensland, Queensland, Australia

Murray Cooper / Strangler Fig (Ficus guianensis) after it has finished parasatizing host plant, Yasuni National Park, Ecuador

Nick Upton / Cuckoo bee (Melecta albifrons) a parasite of Hairy-Footed Flower Bees (Anthophora plumipes) and other masonry bees, searching an old wall for host nests. Brandenburg, Germany, April.

Nick Upton / Cuckoo Bee (Melecta albifrons) a parasite of Hairy-footed flower bees (Anthophora plumipes) emerging from host nest in an old wall. Brandenburg, Germany, April.

Alex Hyde / Giraffe necked weevil {Trachelophorus giraffa} male on leaf of host plant (Dichaetanthera cordifolia) tropical rainforest, Mantadia NP, Madagascar

Alex Hyde / Entomopathogenic fungus covering its deceased host, a tropical grasshopper {Acrididae}, which is still clinging to the plant stem on which it died. tropical rainforest, Andasibe-Mantadia NP, Madagasca...

Alex Hyde / Giraffe necked weevil {Trachelophorus giraffa} female on leaf of host plant (Dichaetanthera cordifolia) tropical rainforest, Mantadia NP, Madagascar

Tim Laman / Close up of Strangler Fig (Ficus sp.) roots wrap around a host tree. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.

Tim Laman / Close up of Strangler Fig (Ficus sp.) roots wrap around a host tree. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.

Tim Laman / Strangler Fig (Ficus sp.) roots wrap around a host tree. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.

Tim Laman / Strangler Fig (Ficus sp.) tree with decomposing host tree visible in the center. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.

Tim Laman / Strangler Fig (Ficus sp.) roots descend a host tree. Lowland rainforest in Borneo. Gunung Palung National Park, Indonesia.