Fern mirid - Felisacus elegantulus
By N A Martin (2015)
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.
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.
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.
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 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.
|Common Name(s)||Scientific Name||Family||Reliability Index||Biostatus|
|Shining spleenwort, Huruhuruwhenua, Parenako, Paretao, Panako, Paranako, Paretao, Ururu whenua||Asplenium oblongifolium Colenso||Aspleniaceae||10||endemic|
|Sickle spleenwort, Petako, Peretao||Asplenium polyodon G.Forst.||Aspleniaceae||10||non-endemic|
|Japanese lady fern||Deparia petersenii (Kunze) M.Kato||Dryopteridaceae||9||non-endemic|
|Diplazium australe (R.Br.) N.A.Wakef.||Dryopteridaceae||9||non-endemic|
|Rasp fern, Pukupuku||Doodia australis (Parris) Parris||Blechnaceae||10||non-endemic|
|Hypolepis ambigua (A.Rich.) Brownsey & Chinnock||Dennstaedtiaceae||10||endemic|
|Giant hypolepis||Hypolepis dicksonionioides (Endl.) Hook.||Dennstaedtiaceae||10||non-endemic|
|Hounds tongue, Hound's tongue fern, Strap fern, kowaowao, paraharaha, kowaowao, Maratata, Paraha, paraharaha, Raumanga||Microsorum pustulatum (G.Forst.) Copel.||Polypodiaceae||10||non-endemic|
|Pteris saxatilis (Carse) Carse||Pteridaceae||10||endemic|
|Shaking brake, Tender brake, Australian bracken, Tarawera, Turawera||Pteris tremula R.Br.||Pteridaceae||10||non-endemic|
|Leather-leaf fern, Pyrrosia||Pyrrosia eleagnifolia (Bory) Hovenkamp||Polypodiaceae||10||endemic|
Fern mirids may be found on ferns in gardens. Ferns are not known to exhibit feeding damage so control is not necessary.
Mirids are opportunists (Wheeler 2001) and it is possible that the fern mirid will prey on fern aphids and other small insects on ferns.
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.
The New Zealand Plant & Food Research Institute Limited (Plant & Food Research) for permission to use photographs.