Fairyfly

'' by John Curtis, c. 1840 The family Mymaridae was first established in 1833 by Irish entomologist Alexander Henry Haliday. Haliday and two close friends, John Curtis and Francis Walker, respected entomologists in their own right, were influential in the early studies of Hymenoptera in the 19th century. History Haliday originally described fairyflies as the tribe "Mymares" of the family "Chalcides". He based his descriptions on the type genus Mymar, described by John Curtis in 1829. "Mymares", as well as other "tribes", were elevated to the family rank (as Mymaridae) by Haliday in 1839. Haliday described fairyflies as "the very atoms of the order Hymenoptera" and remarked on the beauty of their wings when viewed under the microscope. These characteristics of fairyflies also made them popular to entomologists and microscopists of the late 19th and early 20th centuries. The beautifully mounted fairyfly specimens of the early 20th century English microscopist Fred Enock are possibly the most famous of the collections. Etymology The generic name Mymar (and by extension, Mymaridae) was derived by Curtis from the Greek word μΰμαρ (mymar), an Aeolian variant of the standard Greek μῶμος (mōmos, "spot" or "blot"). About 1,424 species of fairyflies are grouped in about 100 genera. The largest genera are Anagrus, Anaphes, Gonatocerus, and Polynema, which comprise around half of all known species. They are the most commonly encountered fairyflies, followed by Alaptus, Camptoptera, Erythmelus, Ooctonus, and Stethynium, which make up a further quarter of known species. The Mymaridae are considered to be monophyletic, but their exact relationships with other chalcidoids remain unclear. No commonly accepted subfamilies have been acknowledged, A fossil subfamily was also proposed for a genus recovered from Canadian amber. ==Description==

Fairyflies are very small insects. They have body lengths from , typically . They can be distinguished from other chalcidoids by having an H-shaped pattern of sutures, known as trabeculae or carinae, below the frontmost ocelli and the inner eye margins. Rarely, the sutures can also extend behind the ocelli. Fairyflies have long antennae, at least as long as the head and the mesosoma (middle part of the body). In females, the antennae are tipped with club-like segments known as clava. In males, the antennae are filiform (thread-like). Forewing curvature, such that it is distinctly convex or dome-shaped, is also exhibited by at least one species of the genera Cremnomymar, Mymarilla, Parapolynema, and Richteria. Most of these species inhabit particularly harsh and wind-swept environments, and the curvature may help in absorbing and retaining heat or prevent the fairyflies from being blown away. Wing reduction or absence is usually exhibited by at least one sex (usually the female) of species that search for host eggs in confined areas (like leaf litter, soil, or the tubules of bracket fungi). Wing reduction or absence is also exhibited by species that inhabit windy habitats like oceanic islands or high elevations, particularly endemic species which are found in isolated habitats or are located far from the nearest mainland. In these habitats, wings would only be a hindrance to the fairyflies, so are strongly selected against in evolution. For example, the three known species of fairyflies found in the far southern islands of Campbell and Auckland of the southwestern Pacific and South Georgia of the southern Atlantic, as well as 20% of the fairyfly fauna in the Juan Fernández Islands, Norfolk Island, and Lord Howe Island, are all wingless or short-winged. While wingless and short-winged species may also be found in islands near continents and in continental habitats, they usually constitute only a small percentage of the overall number of species. Because of their small sizes, fairyflies may sometimes be mistaken for members of the families Aphelinidae and Trichogrammatidae, but members of these other families can readily be distinguished by having much shorter antennae. ==Distribution and habitat==

Fairyflies are some of the most common chalcidoid wasps, but because of their minute sizes they are seldom noticed by humans. This apparent invisibility, their delicate bodies, and their hair-fringed wings have earned them their common name. Among these is Caraphractus cinctus, which uses its wings as paddles to swim. They can remain underwater for as long as 15 days. Because of their small sizes they have to exit the water by climbing up plant stems that jut through the surface, as they would not otherwise be able to break the surface tension of the water. ==Ecology==

All known fairyflies are parasitoids of eggs of other insects. These eggs are commonly laid in concealed locations, such as in plant tissues or underground. but this might be because these groups are simply better studied. Other important host orders include Coleoptera (beetles), Diptera (true flies), Odonata (dragonflies and allies), Psocoptera (booklice and allies), and Thysanoptera (thrips). Hosts are known definitely for only a quarter of known genera. Fairyflies include the smallest known insect, Dicopomorpha echmepterygis from Illinois, whose males are only long. They do not have wings or eyes, their mouths are mere holes, and their antennae are simply spherical blobs. The ends of their legs form suction cups with which they hold on to females long enough to fertilize them. Four males, lined up end-to-end, would just about encompass the width of a period at the end of a typical printed sentence. The smallest flying insect is also a mymarid, Kikiki huna from Hawaii, which is long. Life history '' sp. (female) from Thailand Very little is known of the life histories of fairyflies, as only a few species have been observed extensively. Adult lifespans of fairyflies are very short. '' (female) After emerging, females search rapidly for suitable host eggs by tapping their antennae over stems or barks of plants. When a telltale scar left by egg-laying insects is found, a female will insert her antennae into the recess and check to see if the eggs are suitable. If they are, she will thrust her ovipositor into all of the eggs and lay her own eggs inside in quick succession. She retains contact with each of the eggs with her antennae while doing this. Metamorphosis occurs completely within the host egg. They are peculiar for insects which exhibit complete metamorphosis (holometabolism) in that they produce two distinct kinds of larval instars before pupation. In some fairyflies, such as Anaphes, the first instar is a highly mobile "mymmariform" larva. The second instar, however, is a completely immobile, sac-like larva without discernible segments, spines, or setae. In other fairyflies, such as Anagrus, this is reversed. The first instar is immobile, while the second instar is a very distinctive, highly active "hystriobdellid" larva. At least one instar of the larvae is capable of overwintering when laid in colder seasons. ==Economic importance==

Fairyflies have been used for the biological pest control of various crop pests. They have also been shown to be capable of overwintering in prune leafhoppers (Edwardsiana prunicola). Gonatocerus triguttatus, Gonatocerus tuberculifemur, and Anagrus epos (which is probably a species complex) were also studied for possible use in controlling glassy-winged sharpshooters (Homalodisca vitripennis) in California. Gonatocerus triguttatus and Gonatocerus ashmeadi were eventually introduced in California in 2000. It proved to be very successful, causing about a 90% decline in populations of glassy-winged sharpshooters. In 2005, Gonatocerus ashmeadi was used against invasive glassy-winged sharpshooters in Tahiti and Moorea of the French Polynesia. Again, it was very effective, bringing down the pest density by about 95% in just a year after introduction. It was subsequently also released in the rest of the Society Islands, in the Marquesas, and the Austral Islands, where similar results were obtained against glassy-winged sharpshooters. In South Africa, Anaphes nitens was introduced very successfully to control an undescribed species of eucalyptus snout beetle (Gonipterus sp.). ==Fossil record==

of Gonatocerus greenwalti from Montana Fairyflies are well represented in fossil amber inclusions, copal, and compression fossils. Their fossils have been found from the Early Cretaceous up to the Miocene epoch. It is, in fact, the only family of chalcidoids definitely known to date back to the Cretaceous period. '' from the Burmese amber Cretaceous fairyflies are much rarer. In 1975, Carl M. Yoshimoto described four genera of fairyflies from the Cretaceous of Canada. In 2011, John T. Huber and George Poinar Jr. described the genus Myanmymar from Burmese amber. Dating back to the Lower Cenomanian age (about 100 mya) of the Late Cretaceous, it is the oldest known fairyfly (and chalcidoid). They are surprisingly very similar to modern genera, though with a greater number of flagellar segments and longer forewing veins. The characteristics of the fossil (taking into account Yoshimoto's earlier discoveries) led them to conclude fairyflies either may have existed much earlier than Myanmymar, or they may have diversified rapidly during that time period. ==Genera==

Mymaridae includes the genera listed below. Allomymar and Metanthemus have been transferred to the family Aphelinidae. The fossil genus Protooctonus has been transferred to the family Mymarommatidae, and is now considered to be a synonym of Archaeromma. Nesopolynema, Oncomymar, and Scolopsopteron were synonymized with the genus Cremnomymar in 2013, and their species are now classified under the latter. Genera marked with † are extinct. Extant genera • Acanthomymar Subba Rao, 1970 • Acmopolynema Ogloblin, 1946 • Acmotemnus Noyes & Valentine, 1989 • Agalmopolynema Ogloblin, 1960 • Alaptus Ferrière, 1930 • Allanagrus Noyes & Valentine, 1989 • Allarescon Noyes & Valentine, 1989 • Anagroidea Girault, 1915 • Anagrus Haliday, 1833 • Anaphes Haliday, 1833 • Anneckia Subba Rao, 1970 • Apoxypteron Noyes & Valentine, 1989 • Arescon Walker, 1846 • Australomymar Girault, 1929 • Baburia Hedqvist, 2004 • Bakkendorfia Mathot, 1966 • Boccacciomymar Triapitysn & Berezovskiy, 2007 • Borneomymar Huber, 2002 • Boudiennyia Girault, 1937 • Bruchomymar Ogloblin, 1939 • Caenomymar Yoshimoto, 1990 • Callodicopus Ogloblin, 1955 • Camptoptera Förster, 1856 • Camptopteroides Viggiani, 1974 • Caraphractus Walker, 1846 • Ceratanaphes Noyes & Valentine, 1989 • Chaetomymar Ogloblin, 1946 • Chrysoctonus Mathot, 1966 • Cleruchoides Lin & Huber, 2007 • Cleruchus Enock, 1909 • Cnecomymar Ogloblin, 1963 • Cremnomymar Ogloblin, 1952 • Cybomymar Noyes & Valentine, 1989 • Dicopomorpha Ogloblin, 1955 • Dicopus Enock, 1909 • Dorya Noyes & Valentine, 1989 • Entrichopteris Yoshimoto, 1990 • Eofoersteria Mathot, 1966 • Erdosiella Soyka, 1956 • Erythmelus Enock, 1909 • Eubroncus Yoshimoto, Kozlov & Trjapitzin, 1972 • Eucleruchus Ogloblin, 1940 • Eustochomorpha Girault, 1915 • Eustochus Haliday, 1833 • Formicomymar Yoshimoto, 1990 • Gahanopsis Ogloblin, 1946 • Ganomymar De Santis, 1972 • Gonatocerus Nees, 1834 • Haplochaeta Noyes & Valentine, 1989 • Himopolynema Taguchi, 1977 • Idiocentrus Gahan, 1927 • Ischiodasys Noyes & Valentine, 1989 • Kalopolynema Ogloblin, 1960 • Kikiki Huber & Beardsley, 2000 • Kompsomymar Lin & Huber, 2007 • Krokella Huber, 1993 • Kubja Subba Rao, 1984 • Litus Haliday, 1833 • Macrocamptoptera Girault, 1910 • Malfattia Meunier, 1901 • Mimalaptus Noyes & Valentine, 1989 • Mymar Curtis, 1829 • Mymarilla Westwood, 1879 • Myrmecomymar Yoshimoto, 1990 • Narayanella Subba Rao, 1976 • Neolitus Ogloblin, 1935 • Neomymar Crawford, 1913 • Neostethynium Ogloblin, 1964 • Neserythmelus Noyes & Valentine, 1989 • Nesomymar Valentine, 1971 • Nesopatasson Valentine, 1971 • Notomymar Doutt & Yoshimoto, 1970 • Omyomymar Schauff, 1983 • Ooctonus Haliday, 1833 • Palaeoneura Waterhouse, 1915 • Palaeopatasson Witsack, 1986 • Paracmotemnus Noyes & Valentine, 1989 • Paranaphoidea Girault, 1913 • Parapolynema Fidalgo, 1982 • Parastethynium Lin & Huber, 2007 • Platyfrons Yoshimoto, 1990 • Platypolynema Ogloblin, 1960 • Platystethynium Ogloblin, 1946 • Polynema Haliday, 1833 • Polynemoidea Girault, 1913 • Polynemula Ogloblin, 1967 • Prionaphes Hincks, 1961 • Pseudanaphes Noyes & Valentine, 1989 • Pseudocleruchus Donev & Huber, 2002 • Ptilomymar Annecke & Doutt, 1961 • Restisoma Yoshimoto, 1990 • Richteria Girault, 1920 • Schizophragma Ogloblin, 1949 • Scleromymar Noyes & Valentine, 1989 • Steganogaster Noyes & Valentine, 1989 • Stephanocampta Mathot, 1966 • Stephanodes Enock, 1909 • Stethynium Enock, 1909 • Tanyostethium Yoshimoto, 1990 • Tetrapolynema Ogloblin, 1946 • Tinkerbella Huber & Noyes, 2013 • Zelanaphes Noyes & Valentine, 1989 Fossil genera These fossil genera are classified under Mymaridae: • †Carpenteriana Yoshimoto, 1975 Canadian amber, Late Cretaceous (Campanian) • †Enneagmus Yoshimoto, 1975 Canadian amber, Campanian • †Eoanaphes Huber in Huber & Greenwalt, 2011 Kishenehn Formation, Montana, Eocene (Lutetian) • †Eoeustochus Huber in Huber & Greenwalt, 2011 Kishenehn Formation, Montana, Lutetian • †Macalpinia Yoshimoto, 1975 Canadian amber, Campanian • †Myanmymar Huber in Huber & Poinar, 2011 Burmese amber, Late Cretaceous (Cenomanian) • †Triadomerus Yoshimoto, 1975 Canadian amber, Campanian ==Collection and preservation==

Despite their relative abundance, fairyflies are unpopular among modern insect collectors because of the great difficulty in collecting them. As one of the least known insect families, a large amount of information is still waiting to be discovered about fairyflies. The best modern collection method is using Malaise traps. It requires little maintenance and can collect insects in great abundance. Other effective methods include yellow pan trapping, sweep nets, and suction trapping. Direct collection from leaf litter with Berlese funnels can also result in specimens that can not be collected by other means. Rearing is also another method that can bring the most rewards. This can be done with wild host eggs or laboratory-prepared host eggs that are exposed in suitable habitats outside. They can then be taken in after a sufficient amount of time has passed and examined for developing fairyflies. With this method, it is possible to observe the life history and determine the hosts of particular species of discovered fairyflies. ==See also==