Metcalfa pruinosa (frosted moth-bug)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Metcalfa pruinosa (Say)
Preferred Common Name
- frosted moth-bug
Other Scientific Names
- Ormenis pruinosa (Say)
International Common Names
- English: citrus flatid plant hopper; Citrus planthopper; frosted lightening hopper (USA); mealy lantern fly (USA); moth bug
- METFPR (Metcalfa pruinosa)
- ORMEPR (Ormenis pruinosa)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Hemiptera
- Family: Flatidae
- Genus: Metcalfa
- Species: Metcalfa pruinosa
Notes on Taxonomy and NomenclatureTop of page The trivial name of this distinctive insect has been stable for over 160 years. Usually placed in the genus Ormenis, it was transferred to Metcalfa by Caldwell and Martorell (1951). The tentative synonymy with the Brazilian M. farinosa (Walker) by Van Duzee (1917) seems unlikely to be accurate.
One of the common names applied to this insect is 'frosted lightening hopper' (Stene, 1908). The curious name 'lightening hopper' (or 'lightning hopper' see Chittenden, 1900) apparently derives from the term 'lanternfly' for the type-species of the family, Fulgora laternaria (L.), which was thought to have a luminescent head process. The modern common name for Fulgoroidea is 'planthopper' and the common name for the family to which Metcalfa belongs (Flatidae) is 'moth-bug'. Hence, the recommended common name, modernized from Stene, would be 'frosted moth-bug'.
DescriptionTop of page Adult rather robust with large mothlike wings; 1.5-1.7 mm across eyes, body exclusive of wings 5.0-5.5 mm long, including wings 7.2-8.8 mm long. All except eyes and tarsi covered with waxy pubescence, which together with the bluish black colour of the dorsum gives a pruinose purple colour like that of a ripe plum; venter and two stripes on fore wings (costal margin and claval suture) contrastingly tan.
Crown of head very short, flat both on upper and anterior surfaces between prominent lateral carinae; coronal margin rounding to face; face nearly flat, as long as broad, sides bowed, median carina obscure; clypellus tapered to apex; gena and antennae below eyes, on sides of head; thorax distinctly wider than head across eyes, tegula standing straight out from thorax; pronotum short, a quarter as long as mesonotum, strongly emarginate on caudal edge, mesonotum thus extending forwards to between eyes (Metcalf, 1923); fore wings leaflike, apices expanded and subtruncate, very broad (2.3 times as long as wide across tips, 2.6 times as long as wide at midlength), with numerous veins forming many narrow, unaligned discal and anteapical cells, and close-set costal crossveins forming continuous series with well-defined row of more than 15 apical cells which in turn may be divided by veinal furcations (Metcalf and Bruner, 1948); appendix absent; hind tibia 1.5 times as long as in other legs, bearing a few scattered black-tipped spines towards tip on lateral ridges, and a pecten of 5-7 black-tipped spines at tip; hind tarsi with pecten of 7-8 spines on lower surface of basal segment and only two on slightly shorter second segment.
Female with ovipositor short, upturned between lobes of pygofers; pygofer lobes armed with 5 pairs of strong, sharp, inturned teeth like leaves of Venus flytrap. Male pygofer and subgenital plates not differentiated from ringlike segment IX; anal tube short, with elongate tonguelike process (grooved on midline) above lower angle; styles held vertically, in ventral aspect slender, slightly divergent near tips, in lateral aspect broadening towards tips, bearing recurved hook beyond tip of aedeagus, setose, articulated against undifferentiated sternite IX; connective linear; aedeagus curved dorsad, parallel-margined to truncate tip bearing two pairs of processes directed forward (Metcalf and Bruner, 1948).
Nymph ivory white, strongly dorsoventrally compressed; head much narrower than pronotum, half as wide as thorax across wing pads in mature nymphs; abdomen short and barrel-shaped; pronotum chevron-shaped, with oblique row of prominent, circular pits diverging from midline; scattered pits on apices of wing pads and sides of abdomen (Lucchi and Santini, 1993); legs short and with few spines, becoming more numerous as nymph matures.
DistributionTop of page This eastern Nearctic species was recorded for the first time in Italy in the summer of 1979 in the Province of Treviso (Zangheri and Donadini, 1980) and spread rapidly to all parts of the country, invading adjacent lands. It disperses over short distances by flight, and over long distances by horticulture (Pantaleoni, 1989). Possibly its presence in the southwestern USA is also a result of human activities. Despite the opinion of Dozier (1926), who thought this insect very abundant throughout the entire United States, it is apparently not very common in the northeast and has not been recorded from the Pacific Northwest or the northern prairies.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Hosts/Species AffectedTop of page This polyphagous insect feeds on a wide variety of woody and herbaceous plants with over 200 species of hosts recorded from Italy (Girolami et al., 1996) including Citrus, grapevines, apple, peach, hazel (Zangheri and Donadini, 1980), fig, pear, plum (Duso, 1984), Wisteria, Crataegus, Laurus, Quercus, Spartium (Santini, 1989), Lonicera, hops (Arzone and Vidano, 1990), kiwifruit (Greatti and Girolami, 1994), olive, persimmon (Ciampolini et al., 1995) and Hibiscus (Pasini et al., 1997). In North America, it feeds on 34 genera of native plants representing 20 families, has been found on dahlias, salvias and privet, and has also been reared on green beans (Phaseolus vulgaris) and walnut leaves (Wilson and McPherson, 1981).
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page Fruiting stage, Vegetative growing stage
SymptomsTop of page Dense populations of nymphs cause stunting of the shoots, while those of adults produce large quantities of honeydew on which sooty mould develops. Mould damage is common in gardens but has also increasingly been observed in vineyards (Duso, 1984).
In soyabeans the symptoms of infestation are chlorosis and necrosis of the leaves, smearing of leaves and stalks with wax and sooty mould, withering of shoot tips and malformation and shrivelling of seeds (Ciampolini et al., 1987).
List of Symptoms/SignsTop of page
|Fruit / honeydew or sooty mould|
|Stems / honeydew or sooty mould|
|Whole plant / dwarfing|
Biology and EcologyTop of page This species overwinters as eggs inserted in woody tissue (Wilson and McPherson, 1981) or under tree bark; the first nymphs are found on the leaves and stems in May. The total development period of the nymphal stages is an average of 42 days (Lucchi and Santini, 1993). Nymphs surround themselves with long, waxy filaments which protects them from their copious honeydew. This excreta is utilized by bees when nectar is scarce in summer (Barbattini et al., 1992). Adults are present from July to October (Duso, 1984). The flatid is transported over long distances on vehicles which often park along the roadsides near food plants of the pest. Local invasion of the surrounding area follows and is facilitated by the presence of uninterrupted belts of host trees and shrubs (Pantaleoni, 1989).
Natural enemiesTop of page
Notes on Natural EnemiesTop of page This species is attacked by one or more species of dryinid wasps. Nymphs are parasitized by a mite, Leptus sp., and adults by an epipyropid moth, Epipyrops barberiana Dyar (Wilson and McPherson, 1981), neither of which kill their host.
Neodryinus typhlocybae was imported into Italy from the USA for biological control of M. pruinosa (Girolami et al., 1996) but it is not clear whether it was released and, if so, whether it became established.
ImpactTop of page Of primary concern are grapevines and fruit trees such as fig, lemon, apple, pear, plum and peach (Duso, 1984) where the fruit may be unsalable due to mould and markings. Serious damage was recorded on soyabean in northern Italy; in 1986, increased attacks led to a 30-40% crop loss (Ciampolini et al., 1987).
Detection and InspectionTop of page Both adults and nymphs are plainly seen when resting or feeding on stems and twigs.
Similarities to Other Species/ConditionsTop of page From other flatids with similar colouration this may be distinguished by (1) the head is flat, not produced, (2) the fact that the front wings are not truncate, but have rounded corners, and (3) by the moderate size, not so small as the tropical species of Metcalfa, nor gigantic as in Hansenia.
Prevention and ControlTop of page
Chemical control against dense nymphal populations might be justified on valuable trees, but control of sooty mould by means of fungicides is usually more useful. Chemical control of adults is difficult owing to their mobility and long life (Duso, 1984). For chemical control, timing is of the utmost importance, and at the very first signs of infestation, malathion, acephate, fenitrothion or pyrethroids should be applied at the edges of the fields (Ciampolini et al., 1987). Insecticide applications should be kept to a minimum; one application should be made on the crop and wild plants at the end of July/beginning of August to eliminate immature nymphs and newly-emerged adults, and a second application should be made on wild plants in the first half of August to prevent the adults from reinvading the crop.
On fruit crops which already receive calendar treatments of insecticides, a product effective against M. pruinosa could be inserted into the control programme at these times. (Ciampolini et al., 1995). The most effective insecticides were fenitrothion and quinalphos. Deltamethrin gave good control while pyridaphenthion gave mediocre control. Dimethoate gave better control on the leaves than on the fruit. Chlorpyrifos-methyl needed to be sprayed directly onto the adults to achieve maximum efficacy. Acephate, lambda-cyhalothrin, dimethoate, pyridaphenthion and deltamethrin persisted for 5-8 days, and then quinalphos, fenitrothion and chlorpyrifos-methyl (0-2 days). Chlorpyrifos-methyl, deltamethrin and quinalphos had a repellent activity, accounting for their low levels of persistence. (Stefanelli et al., 1994). Etofenprox had a sufficient and prolonged efficacy, contrasting with the high and brief activity of malathion. Applications of imidacloprid, a well-known systemic insecticide, in granular form to the foot of the plant or in liquid form to the trunk abolished negative effects on the urban population normally caused by spray treatments. Neem oil was not active against the adults, but it is suggested that it could be active against immature stages (Pasini et al., 1997).
Soap solutions cause almost all of the young stages of the pest to fall to the ground. In the absence of insecticide treatments, the colonies reform 8-10 days later. The treatment is also highly effective in washing away from the plants wax secretions and honeydew produced by the flatid. The treatment should be made as late as possible but before the appearance of adults (Greatti and Girolami, 1994).
ReferencesTop of page
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Distribution MapsTop of page
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