Fern mirid - Felisacus elegantulus

By N A Martin (2015, revised 2017)

Caption:

Classification

Phylum

Arthropoda

Class

Insecta

Order

Hemiptera

Family

Miridae

Scientific name

Felisacus elegantulus (Reuter, 1904)

Common names

Fern mirid

Synonyms

Hyaloscytus elegantulus Reuter, 1904

Biostatus and distribution

This native mirid is widespread in the North Island, while it is found only in the Marlborough Sounds and Nelson in the South Island. It is also present in Australia. It occurs on its fern host plants in city gardens and parks as well as native ecosystems.

Conservation status: Widespread, not threatened.

Life stages and annual cycle

Adults and nymphs of this insect can be found at all times of the year in Auckland.

Adults tend to be found on host ferns that have sporangia (groups of spores) present. The female has a pointed end to her abdomen that houses the ovipositor, while the male genitalia are contained in a bulbous structure, called the genital capsule, at the end of the abdomen. The female uses her ovipositor to insert eggs into fern fronds.

Nymphs hatch from the eggs. There are five nymphal stages, each called an instar. Nymphs go from one stage to the next by moulting. During moulting, the skin on the dorsal side splits and the next stage pulls itself out of the old skin. First instar nymphs are like small, green, wingless adults. Later instars have red marks on their body, and the last two instars have wing buds. Nymphs have a pointed anal tube at the end of the abdomen that is particularly obvious in the later instars. Adults emerge from fifth instar nymphs.

Walking and flying

The nymphs and adults have three pairs of legs. The adults have two pairs of wings held over their body. The wings are transparent with dark veins.

Feeding

Like other Hemiptera, the fern mirid has piercing and sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. When it wishes to feed, the bug moves the tip of the rostrum to a suitable part of the plant. The stylets are then gradually pushed into the plant. The stylets form two tubes, one through which saliva is injected into the plant and a second through which plants juices are sucked up into the insect. Feeding of the fern mirid has not been studied, but it probably can use its saliva to digest the tissues of the plant.

An adult female fern mirid, Felisacus elegantulus (Hemiptera: Miridae) from above. Creator: Tim Holmes. © Plant & Food Research. [Image: 15K8]

An adult fern mirid, Felisacus elegantulus (Hemiptera: Miridae) in part frontal view with the rostrum extended. Creator: Tim Holmes. © Plant & Food Research. [Image: 15KA]

Side view of an adult female fern mirid, Felisacus elegantulus (Hemiptera: Miridae), note the rostrum extending backwards and the bulky abdomen, sloping upwards at the rear. Creator: Tim Holmes. © Plant & Food Research. [Image: 15KB]

Side view of an adult male fern mirid, Felisacus elegantulus (Hemiptera: Miridae), note the bulbous genital capsule at the end of the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 15KC]

An early instar nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K6]

A nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K5]

A nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K4]

Nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K2]

Side view of a nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of leather-leaf fern, Pyrrosia eleagnifolia (Polypodiaceae); note the upturned pointed end to the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 15K1]

Recognition

The fern mirid is the only mirid that breeds on New Zealand ferns. The only other hemipterans (sucking bug) that breed on New Zealand ferns are aphids. The fern aphid, Idiopterus nephrelepidis Davis, 1909 (Hemiptera: Aphididae) is black. Two of the other aphid species are green and may be confused with the fern mirid, especially when they may occur on the same species of fern. The adult mirid looks quite different, being long and thin with wings held horizontally over the body, while aphids are more globular and the winged aphids hold their wings vertically above their body. The fern mirid nymphs are also quite different in appearance to fern aphids, the mirid being long and thin with antennae held out front while wingless aphids tend to be shorter and have two siphuncles at the back.

Adult fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K7]

Nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K2]

Wingless female green fern aphid Micromyzella filicis (van der Goot, 1917) (Hemiptera: Aphididae). Creator: Tim Holmes. © Plant & Food Research. [Image: 3EQ]

Nymphs of the green fern aphid Micromyzella filicis (van der Goot, 1917) (Hemiptera: Aphididae) that lives on ferns. Creator: Tim Holmes. © Plant & Food Research. [Image: 3ER]

Winged green fern aphid Micromyzella filicis (van der Goot, 1917) (Hemiptera: Aphididae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 1WTH]

Nymphs and wingless female of the lily aphid, Neomyzus circumflexus (Hemiptera: Aphididae) on young frond of Single crepe fern, Leptopteris hymenophylloides (Osmundaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1HYU]

Winged female of the lily aphid, Neomyzus circumflexus (Hemiptera: Aphididae) on young frond of Single crepe fern, Leptopteris hymenophylloides (Osmundaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1HYV]

Winged female black fern aphid Idiopterus nephrelepidis Davis, 1909 (Hemiptera: Aphididae). The large forewings have black veins and the smaller hind wings are pale. Creator: Tim Holmes. © Plant & Food Research. [Image: 15JT]

Nymphs and a wingless female black fern aphid Idiopterus nephrelepidis Davis, 1909 (Hemiptera: Aphididae); the arrows point to one of the two cornicles and the cauda. Creator: Tim Holmes. © Plant & Food Research. [Image: 15JL]

Natural enemies

There are no reports of natural enemies of the fern mirid, but it is likely that they are preyed on by birds, insect predators, and spiders.

Host plants

Host plants are native fern species from five families. Adults and juveniles feed by inserting their stylets into the plant. It is assumed that they inject saliva into plant cells and then suck out partly digested cell contents. They may also feed on unripe spores.

Top side of a nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of leather-leaf fern, Pyrrosia eleagnifolia (Polypodiaceae); note the upturned pointed end to the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 15JY]

A nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K4]

Nymph of the fern mirid, Felisacus elegantulus (Hemiptera: Miridae) on the underside of Shaking brake, Pteris tremula (Pteridaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15K2]

Table: Host plants of the Fern mirid, *Felisacus elegantulus* (Hemiptera: Miridae) from Plant-SyNZ database (24 July 2017). The reliability score shows the quality of evidence for the host association (1-10, 10=high).
Common Name(s)	Scientific Name	Family	Reliability Index	Biostatus
Shining spleenwort, Huruhuruwhenua, Parenako, Paretao, Pānako, Paranako, Paretao, Urūru whenua	Asplenium oblongifolium Colenso	Aspleniaceae	10	endemic
Sickle spleenwort, Petako, Peretao	Asplenium polyodon G.Forst.	Aspleniaceae	10	indigenous, non-endemic
Rasp fern, Pukupuku	Blechnum parrisiae Christenh.	Blechnaceae	10	indigenous, non-endemic
Japanese lady fern	Deparia petersenii (Kunze) M.Kato	Dryopteridaceae	9	indigenous, non-endemic
	Diplazium australe (R.Br.) N.A.Wakef.	Dryopteridaceae	10	indigenous, non-endemic
Water fern, Histiopteris, Mātā, Mātātā	Histiopteris incisa (Thunb.) J.Sm.	Dennstaedtiaceae	10	indigenous, non-endemic
	Hypolepis ambigua (A.Rich.) Brownsey & Chinnock	Dennstaedtiaceae	10	endemic
Giant hypolepis	Hypolepis dicksonionioides (Endl.) Hook.	Dennstaedtiaceae	10	indigenous, non-endemic
Hounds tongue, Hound's tongue fern, Strap fern, kōwaowao, pāraharaha, kōwaowao, Maratata, Pāraha, pāraharaha, Raumanga	Microsorum pustulatum (G.Forst.) Copel.	Polypodiaceae	10	indigenous, non-endemic
Coastal brake, Netted brake	Pteris comans G.Forst.	Pteridaceae	10	indigenous, non-endemic
Sweet fern	Pteris macilenta A. Rich.	Pteridaceae	10	indigenous, non-endemic
	Pteris saxatilis (Carse) Carse	Pteridaceae	10	endemic
Shaking brake, Tender brake, Australian bracken, Tarawera, Turawera	Pteris tremula R.Br.	Pteridaceae	10	indigenous, non-endemic
Leather-leaf fern, Pyrrosia	Pyrrosia eleagnifolia (Bory) Hovenkamp	Polypodiaceae	10	endemic

Control

Fern mirids may be found on ferns in gardens. Ferns are not known to exhibit feeding damage so control is not necessary.

Additional information

Mirid opportunists

Mirids are opportunists (Wheeler 2001) and it is possible that the fern mirid will prey on fern aphids and other small insects on ferns.

Information sources

Eyles AC, Schuh RT 2003. Revision of New Zealand Bryocorinae and Phylinae (Insecta: Hemiptera: Miridae). New Zealand Journal of Zoology 30: 263-325.

Lariviere M-C, Larochelle A 2004. Heteroptera (Insecta: Hemiptera): catalogue. Fauna of New Zealand 50: 1-326.

Plant-SyNZ: Invertebrate herbivore-host plant association database. plant-synz.landcareresearch.co.nz/.

Wheeler AG 2001. Biology of the plant bugs (Hemiptera: Miridae): pests, predators, opportunists. New York, Cornell University Press. 506 p.

Acknowledgements

The New Zealand Plant & Food Research Institute Limited (Plant & Food Research) for permission to use photographs.

Update history

1 August 2017. NA Martin. Host plant table updated.

INTERESTING INSECTS

and other invertebrates