The Isles of Scilly are an archipelago off Land's End, Cornwall. Little of the fauna on, above or in the seas surrounding the isles was described prior to the 19th century, when birds and fish started to be described. Most records of other animals date from the 20th century onwards.

Historical overview There are few pre-19th-century records for animals. William Borlase published The Natural History of Cornwall in 1758, commenting on the number of rabbits, and Jonathan Couch's A Cornish Fauna gave an account of some the animals known in mainland Cornwall and the Isles of Scilly. In the 19th century, following the fashion of the time, birds were shot and stuffed, especially by Augustus Smith and his predecessors on Tresco. Egg collecting was allowed and in the Natural History Museum there are, in the collection, forty-five eggs taken between 1880 and 1936 from Annett, even though it was a bird sanctuary.Robinson, P. (2003) The Birds of the Isles of Scilly. London: Christopher Helm. Newspapers recorded some of the fish caught but there was little recording of other groups of animals.

It was in the 20th century when regular accounts can be found for other animal groups following visits from naturalists who often published their observations in the scientific literature. For example, William Bristow visited the islands on three occasions from 1927 to 1934, recording spiders including on some of the uninhabited islands. The Cornwall Bird Watching and Preservation Society published bird reports from the 1930s onwards and the Isles of Scilly Bird Group (founded 2000) took over publishing their own annual reports – Isles of Scilly Bird and Natural History Review – which included other groups of animals such as the diptera.

Planarian (flatworms) Fourteen species of terrestrial flatworms have been recorded in Britain and Ireland with five found on the Isles of Scilly. Only three or four of the fourteen species are native with two recorded on Tresco.

The Australian flatworm (Australoplana sanguinea) – a flatworm from Australia and New Zealand and first found on Tresco in 1960. Now found in many parts of Britain. Feeds on earthworms. Australopacifica coxii – a flatworm from Australia and found on Tresco in 1975. Feeds on earthworms. Kontikia andersoni – found on Tresco in 1984; it is native to Australia and/or New Zealand. Microplana terrestris – recorded on Tresco (1982). Native Microplana scharffi – recorded on Tresco (1984) and St Mary's (1985). Native

Opiliones (harvestmen) Dicranopalpus ramosus Leiobunum blackwalli – found on all the inhabited islands, Annet and Great Innisvouls. Leiobunum rotundum – recorded on Tean, Tresco and St Martin's. Nelima gothica – found on St Mary's and Tresco. Nelima silvatica Opilio saxatilis Phalangium opilio – found on St Martin's, St Mary's, Samson and Tresco.

Odonata The Atlas of the Dragonflies of Britain and Ireland published in 1996 listed just three species; blue-tailed damselfly, common darter (both breeding residents) and the migrant hawker. The pools can be slightly brackish at times and only species that can tolerate these conditions can establish populations on the islands.

Steve Jones compiled a list which was published in the Cornwall Dragonfly Group Newsletter (numbers 6–8) and the list below is based on that information. In comparison, at that time, Cornwall had 23 breeding species and 28 species recorded. Common blue damselfly (Enallagma cyathigerum) – in 1994 an ovipositing female was at Lower Moors, St Mary's. Blue-tailed damselfly (Ischnura elegans) – can tolerate brackish conditions and breeds on St Agnes, St Mary's and Tresco. Migrant hawker (Aeshna mixta) – increased sightings since the mid-1990s on St Agnes, St Mary's and Tresco. Southern hawker (A. cyanea) – recorded on St Mary's in October 1992 and October 1996 and from Tresco also in October 1996. Common hawker (A. juncea) – Great Pool, Tresco in October 1992. Emperor dragonfly (Anax imperator) – individuals seen on St Mary's, September 1992 and August 1996. Green darner (A. junius) – At least two individuals (male and female) were found on St Agnes on 10 September 1998 (just one day after the first record for the Western Palaearctic in Cornwall, the previous day). There was a male on St Mary's during the following week and a female on Tresco on 30 September and the next day. Golden-ringed dragonfly (Cordulegaster boltonii) – October 1996 on Tresco. Red-veined darter (Sympetrum fonscolombii) – two males on Great Pool, Tresco, May 1992. Yellow-winged darter (S. flaveolum) – one seen on St Mary's during the ″Invasion Year″ of 1995. Common darter (S. striolatum) – breeding on St Agnes, St Mary's and Tresco.

Orthopteroid The Orthopteroids have been recorded in Scilly since 1890 and specialists have visited the islands since 1989 to give, what is considered, complete coverage of these insects. The list below is taken from Orthopteroid Insects on Scilly (2001) with additional records referenced.

Orthoptera (crickets and grasshoppers) Oak bush-cricket (Meconema thalassinum) – one seen on Tresco in 1960. Great green bush-cricket (Tettigonia viridissima) – resident on St Mary's and Tresco and probably an Allerød pioneer. Dark bush-cricket (Pholidoptera griseoaptera) – one seen on Tresco in 1906. Grey bush-cricket (Platycleis albopunctata) – resident on Bryher and a probable Allerød pioneer. The numbers in the colony fluctuates. Long-winged cone-head (Conocephalus fuscus) – a recent resident, discovered in 1990 on St Martin's and St Mary's, on Gugh and St Agnes in 1994 and Tresco in 1996. Short-winged cone-head (Conocephalus dorsalis) – a recent resident, the first confirmed record was from St Agnes in 1992 and found on St Mary's in 1996 on Lower Moors. Three known populations including Lower Moors, St Mary's. Speckled bush-cricket (Leptophyes punctatissima) – a recent resident, one was found near the Garrison on St Mary's in 1991. In 2000 a small population was found. House cricket (Acheta domestica) – in 1992 found on St Mary's at Porthloo rubbish tip. Mole cricket – one found on St Mary's in 1932. The specimen was donated to the Royal Cornwall Museum in Truro and refound by Stella Turk in 1998. Common groundhopper (Tetrix undulata) – probably introduced on horticultural material and found in Tresco Abbey Gardens in circa 1960. Since found on Abbey Pool where there is a large population. Desert locust (Schistocerca gregaria) – there are records going back to the 19th century and one was found on St Mary's in the autumn of 1988. Migratory locust (Locusta migratoria) – one found on St Mary's in October 1998. Blue-winged grasshopper (Oedipoda caerulescens) – one recorded in the Victoria County History (1906) in 1903. Field grasshopper (Chorthippus brunneus) – a probable Allerød pioneer, resident, widespread and numerous on the Annet, Bryher, Great Arthur, Great Ganilly, Great Ganinick, Gugh, Little Arthur, Little Ganilly, Menawethan, Northwethel, Samson, St Agnes, St Helens, St Martin's, St Mary's, Tean and Tresco.

Dictyoptera (cockroaches) Oriental cockroach (Blatta orientalis) – an established introduction and until the early 20th century was a widespread indoor pest. Still found in some premises on St Martin's, St Mary's and Tresco. German cockroach (Blattella germanica) Lesser cockroach (Ectobius panzeri)

Phasmatodea (stick insects) Prickly stick insect (Acanthoxyla geisovii) Smooth stick insect (Clitarchus hookeri) Mediterranean stick insect (Bacillus rossius) – first found on Tresco in 2002. Laboratory stick insect (Carausius morosus) – first found on St Mary's in 2007and St Agnes in 2009.

Dermaptera (earwigs) Lesser earwig (Labia minor) Common earwig (Forficula auricularia) Lesne's earwig (Forficula lesnei)

Lepidoptera In 1992 Michael Hicks and John Hale began to regularly record the moths on St Agnes using a mercury vapour moth trap, initially in the central part of the island and later also on the coast and Gugh. Previously moths had been recorded by visitors on short stays. Their book recorded 213 species of macro moths, 171 species of micro moths and 28 species of butterflies. The list below is taken from Hicks and Hale (1998) with additional records referenced.

Micro moths Nepticulidae Stigmella aurella – a common leaf miner on bramble

Psychidae Psyche casta – the larvae feed on elm (Ulmus sp.)

Tineidae

Psychoides filicivora – larvae feed on the sori of ferns, including lanceolate spleenwort (Asplenium obovatum) on Bryher Infurcitinea argentimaculella Monophis laevigella M. crocicapitella Tinea pallescentella T. trinotella Yellow v moth (Oinophila v-flava) – in Britain and Ireland the moth is found usually indoors in, for example, wine cellars and warehouses, where the larva feeds on wine corks and fungus. Larvae were found under the flaking bark of Pittosporum crassifolium by Robert Heckford in 1986 at Old Town Bay, St Mary's.

Gracillariidae

Gracillaria syringella Aspilapteryx tringipennella Calybites phasianipennella – larval cones can be found on common sorrel (Rumex acetosa) Phyllonorycter messaniella

Sesiidae Thrift clearwing (Pyropteron muscaeforme) – recorded around the coast on thrift (Armeria arenaria)

Choreutidae Nettle-tap moth (Anthophila fabriciana) Tebenna micalis – first Isles of Scilly record from St Agnes on 19 June 1998

Glyphipterigidae Cocksfoot moth (Glyphipterix simpliciella) – also found on Gugh

Yponomeutidae Orchard ermine (Yponomeuta padella) Apple ermine (Y. malinellus) Spindle ermine (Y. cagnagella) – recorded, on St Agnes, at light in August 1994. The food plant, European spindle (Euonymus europaeus), is not found on the islands. Swammerdamia pyrella

Plutellidae Diamond-back moth (Plutella xylostella) – can be abundant and numbers reinforced by migration. When walking among crops can have hundreds flying ahead of each footfall. Rhigognostis annulatella – the larva food plant is common scurvygrass (Cochlearia officinalis), a common plant on Scilly.

Epermeniidae Epermenia chaerophyllella – recorded as "not common", the larvae and larval feeding signs are easily found on hogweed (Heracleum sphondylium). E. aequidentellus – larvae and larval feeding signs can be found on wild carrot. (Daucus carota).

Schreckensteiniidae Schreckensteinia festaliella

Coleophoridae

Coleophora serratella C. frischella C. deauratella C. laricella – the only record for this larch miner is by the bibliographer, Francis Jenkinson on St Agnes before 1894. Larch has not been recorded on the islands. C. discordella C. argentula – the larvae can be found feeding in a case on the seedheads of Achillea millefolium. C. vestianella

Elachistidae Elachista argentella E. consortella

Oecophoridae

Batia lambdella – one trapped on Gugh on 9 July 1995, the first for the Isles of Scilly. Brown house moth (Hofmannophila pseudospretella) White-shouldered house moth (Endrosis sarcitrella) Esperia sulphurella – frequently seen, on St Agnes, flying around gorse (Ulex europaeus).

Depressariidae

Parsnip moth (Depressaria radiella) D. badiella Agonopterix heracliana A. alstromeriana A. umbellana A. nervosa A. yeatiana A. rotundella – to light on St Mary's, 13 October 2018

Gelechiidae

Monochroa cytisella – the larva forms a gall on bracken (Pteridium aquilinum). Teleiopsis diffinis Bryotropha desertella Mirificarma mulinella Scrobipalpa samadensis S. ocellatella S. costella Caryocolum viscariella Nothris congressariella – common and widespread on the islands, the larvae feed between spun leaves of balm-leaved figwort (Scrophularia scorodonia) and was first recorded on Tresco in 1957. At that time it was not known from anywhere else in Britain and Ireland. Has since been found on the Channel Islands (1982), near Newquay (1987) and Lundy Island 1995. Anarsia spartiella Brachmia blandella

Autostichidae Oegoconia caradjai

Blastobasidae