Thomas Hinsche / Eurasian Reed-Warbler (Acrocephalus scirpaceus) feeding Common Cuckoo (Cuculus canorus) chick, Saxony-Anhalt, Germany

Thomas Hinsche / Eurasian Reed-Warbler (Acrocephalus scirpaceus) feeding Common Cuckoo (Cuculus canorus) chick, Saxony-Anhalt, Germany

Richard Du Toit / Burchell's Zebra (Equus burchellii) reacting to parasitic Bot Fly (Oestridae) trying to lay eggs on it, KwaZulu-Natal, South Africa

Piotr Naskrecki / Tick, Gorongosa National Park, Mozambique

Piotr Naskrecki / Soft Scale Insect (Coccidae) group with parasitic wasps, Gorongosa National Park, Mozambique

Stephen Dalton / Ant infected by entomopathogenic fungus, which has taken over the brain of the ant, Florida, USA, February.

Stephen Dalton / Tachinid fly (Alophora hemiptera) parasitic species. Sussex, England, UK, August.

Bertie Gregory / Humpback whale (Megaptera novaeangliae) close up of barnacles on pectoral fin, Vancouver Island, British Columbia, Canada, July.

Doug Wechsler / Gall (Polystepha pilulae) on Pin Oak (Quercus palustris) Morris Arboretum, Philadelphia, Pennsylvania, USA, August.

Doug Wechsler / Dodder (Cuscuta) parasitic plant on Goldenrod (Solidago) Bloomfield Farm, Morris Arboretum, Philadelphia, Pennsylvania, USA, August.

David Tipling / Reed Warbler (Acrocephalus scirpaceus) feeding Cuckoo (Cuculus canorus) chick in reedbed nest, Norfolk, May.

Michael Durham / Female Phorid / Shuttle fly (Pseudacteon obtusus) in flight above Red imported fire ants (Solenopsis invicta) searching for an ant to implant with an egg, Texas, USA, March.

Michael Durham / Carrion beetle (Nicrophorus carolinensis) in flight with parasitic mites living on exoskeleton, Texas, USA, September.

Michael Durham / Bat bug (Heteroptera) ectoparasite feeding on part of the wing of a Big brown bat (Eptesicus fuscus) Arizona, USA, July.

Aflo / Great Reed Warbler (Acrocephalus arundinaceus) feeding Cuckoo (Cuculus sp) chick, Japan.

Aflo / Great Reed Warbler (Acrocephalus arundinaceus) feeding Cuckoo (Cuculus sp) chick, Japan.

Daniel Heuclin / Human botfly (Dermatobia hominis) larvae, on leaf, French Guiana.

Daniel Heuclin / Human botfly (Dermatobia hominis) larvae, on leaf, French Guiana.

Daniel Heuclin / Human botfly (Dermatobia hominis) larvae in dogs skin, showing breathing tube, French Guiana.

Daniel Heuclin / Human botfly (Dermatobia hominis) larvae in dogs skin, showing breathing tube, French Guiana.

Daniel Heuclin / Human botfly (Dermatobia hominis) larvae, on dog fur, French Guiana.

D. Parer & E. Parer-Cook / Common Wombat (Vombatus ursinus) with sarcoptic skin mange, which will eventually kill it, southeastern Australia

Suzi Eszterhas / Gray Whale (Eschrichtius robustus) skin covered with barnacles and whale lice, San Ignacio Lagoon, Baja California, Mexico

Adrian Davies / Bonnet mould (Spinellus fusiger) growing parasitically on a Saffrondrop bonnet (Mycena crocata), Sussex, England, UK, October.

Nature Production / Great Reed Warbler (Acrocephalus arundinaceus) removing cuckoo's egg from nest, Minamimaki village, Nagano Prefecture, Japan

D. Parer & E. Parer-Cook / Platypus (Ornithorhynchus anatinus) with Platypus Tick (Ixodesáornithorhynchi) females attached to its skin, native to Australia

Chien Lee / Tent Caterpillar Moth (Lasiocampidae) caterpillar covered with empty cocoons of parasitic wasps which have emerged after feeding on its body, Mount Kinabalu National Park, Borneo, Malaysia

Chien Lee / Rafflesia (Rafflesia keithii) pair flowering, largest flower in the world, Sabah, Borneo, Malaysia

Chien Lee / Rafflesia (Rafflesia keithii) pair flowering, largest flower in the world, Sabah, Borneo, Malaysia

Chien Lee / Fungus (Ophiocordyceps dipterigena) parasitic mushrooms emerging from robber fly after it has consumed its interior, Tangkoko Nature Reserve, Indonesia

Chien Lee / Cicada (Cicadidae) killed by a parasitic fungus, Kibale National Reserve, Uganda

Mark Moffett / Black Oak Acorn Weevil (Curculio rectus) grub emergening from acorn, Myles Standish State Forest, Massachusetts

Cyril Ruoso / Leaf infested by parasites, Barro Colorado Island, Panama

Duncan Usher / Sheep Tick (Ixodes ricinus) female engorged with blood, Lower Saxony, Germany

Juergen Freund / Dead ant (Formicidae sp) infected by Ophiocordyceps fungus. Tanjung Puting National Park, Borneo, Central Kalimantan, Indonesia

D. Parer & E. Parer-Cook / Little Blue Penguin (Eudyptula minor) chick with ticks during molt, Phillip Island, Australia

D. Parer & E. Parer-Cook / Leech, sucking blood from hand, Australia

Hiroya Minakuchi / Gray Whale (Eschrichtius robustus) skin covered in barnacles, San Ignacio Lagoon, Baja California, Mexico

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

Piotr Naskrecki / Parasitic Plant (Helosis cayennensis) pair in rainforest, 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

Nick Upton / Yellow dung fly (Scathophaga stercoraria) killed by pathogenic fungus of flies (Entomophthora muscae) clinging to a thistle leaf with wings spread, Wiltshire pastureland, UK, June.

Sue Daly / Female Cuckoo Wrasse (Labrus mixtus) with parasites (Anilocra frontalis). Guillaumesse, Sark, British Channel Islands, July.

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

Sumio Harada / Gray Wolf (Canis lupus) diseased with scabies, Yellowstone National Park, Wyoming

Yukihiro Fukuda / Close up of the mouth and nose of a Japanese giant salamander (Andrias japonicus) with two Leeches (Hirudinea) attached, Japan, March

Pete Oxford / Chalcid Wasp (Chalcididae) group parasitizing butterfly pupa, Tiputini Biodiversity Station, adjacent to Yasuni National Park, Amazon Rainforest, Ecuador

Tony Phelps / Broadleaf sugarbush (Protea eximia) infected with bacterial parasite (Phtoplasma sp) causing Witch's broom, a growth deformity. Swartberg Mountains, western Cape, South Africa.

Konrad Wothe / Leech on skin in rainforest, West Papua, Indonesia

Mark Moffett / Green Tree Ant (Oecophylla smaragdina) in defensive posture as parasitic wasps attempt to lay eggs on colony members, Daintree, Queensland, Australia

Pete Oxford / Sac Fungus (Cordyceps sp) parasitizing spider, Yasuni National Park, Amazon, Ecuador

Pete Oxford / Sac Fungus (Cordyceps sp) parasitizing moth, Yasuni National Park, Amazon, Ecuador

Martin Willis / Atherton Scrubwren (Sericornis keri) feeding Fan-tailed Cuckoo (Cacomantis flabelliformis) chick at its nest, Atherton Tableland, Queensland, Australia

Andy Sands / Ruby Tailed Wasp (Hedychrum niemelai / rutilans) approaching the burrow of Cerceris arenaria which it will parasitise with its larvae. London, England, UK, July.

Konrad Wothe / Sheep Tick (Ixodes ricinus) engorged with blood on skin, Bavaria, Germany

Hiroya Minakuchi / Gray Whale (Eschrichtius robustus) with barnacles and whale lice, Baja California, Mexico

Piotr Naskrecki / Chalcid Wasp (Chalcididae) parasite newly emerged from butterfly chrysalis, Sipaliwini, Surinam

Piotr Naskrecki / Vampire Bat (Desmodus rotundus) with parasitic Louse Flies (Trichobius parasiticus) behind its ear, Sipaliwini, Surinam

Piotr Naskrecki / Carpenter Ant (Camponotus sp) parasitized and killed by Sac Fungus (Cordyceps sp), Sipaliwini, Surinam

Piotr Naskrecki / Chalcid Wasp (Chalcididae) parasite emerging from butterfly chrysalis, Sipaliwini, Surinam

Piotr Naskrecki / Parasitic Plant (Helosis cayennensis) obtains nutrients from roots of other plants, Sipaliwini, Surinam

Piotr Naskrecki / Sac Fungus (Cordyceps sp) mycelium covering cricket that was parasitized and killed by the fungus, Sipaliwini, Surinam

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

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...

Steve Gettle / Magnificent Frigatebird (Fregata magnificens) male stealing food from Red-billed Tropicbird (Phaethon aethereus), Galapagos Islands, Ecuador

Alex Hyde / Sand wasp (Ammophila sp) female with a caterpillar that has been stung and paralysed, Midi-Pyrenees, France, August.

John Abbott / Blueberry / Mason bee (Osmia ribifloris) on old nest of Trypoxylon mud dauber wasp with Sapygid wasp (Sapyga nevadica) flying in to parasitize the bee, Texas, USA, March

Piotr Naskrecki / Bed Bug (Cimex lectularius) filled with blood, Estabrook Woods, Concord, Massachusetts

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

Christian Ziegler / Harlequin Beetle (Acrocinus longimanus) with pseudoscorpion and an abundance of red mites, Barro Colorado Island, Panama

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

James Christensen / Tarantula (Theraphosidae) carcass with the parasitic fly larvae that killed it, Mindo, western slope of Andes, Ecuador

Piotr Naskrecki / Wingless Bat Fly (Nycteribiidae) parasite on bat wing membrane, Papua New Guinea

Piotr Naskrecki / Biologist Ingi Agnarsson collecting kleptoparasitic spiders that live as squatters in the web of the giant orb weaver, Papua New Guinea

Piotr Naskrecki / One-flower Indian-pipe (Monotropa uniflora) flowers, Estabrook Woods, Massachusetts

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus) on Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus) on Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus) with Reed warbler on Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Reed Warbler (Acrocephalus scirpaceus) returns to nest to feed 12 day Cuckoo chick (Cuculus canorus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Reed Warbler (Acrocephalus scirpaceus) on nest with 12 day chick Cuckoo (Cuculus canorus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), warbler brings insect prey to nest to feed chick, Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Reed Warbler (Acrocephalus scirpaceus) pair at nest feeding 12 day Cuckoo chick (Cuculus canorus), Fenland, Norfolk, UK, May

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

Christian Ziegler / Bat Fly (Streblidae) ecto parasite on the wing of Great Fruit-eating Bat (Artibeus lituratus), Smithsonian Tropical Research Station, Barro Colorado Island, Panama

Christian Ziegler / Parasitic mite on millipede, Lambir Hills National Park, Sarawak, Malaysia

David Tipling / 2020VISION / Reed warbler (Acrocephalus scirpaceus) feeding 12 day chick of European cuckoo (Cuculus canorus) in its nest, East Anglian Fens, Norfolk, May