''Mayetiola piceae'', the spruce gall midge, is a species of

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

-forming flies in the

Cecidomyiidae Cecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls. Cecidomyiidae are very fragile small insects us ...

family. An outbreak of spruce gall midge occurred in northern Alberta and adjacent areas in the Northwest Territories in 1992 (Brandt 2000).Brandt, J.P. 2000. A sequential sampling plan for classification of damage caused by spruce gall midge (''Mayetiola piceae''

elt ELT may refer to: Education * English language teaching * Expanded learning time, an American education strategy * Kolb's experiential learning theory Mathematics and science * Ending lamination theorem * Extremely large telescope, a type of ...

. Nat. Resour. Can., Can. For. Serv., Edmonton AB, For. Manage. Note 65. 7 p. The infestation was widespread in

white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to: * ''Picea glauca'', native to most of Canada and Alaska with limited populations in the northeastern United States * ''Picea engelmannii ''Picea engelman ...

stands, with 84% of surveyed sites infested and twig mortality as high as 81% among current-year shoots. Earlier, Rose and Lindquist (1985)Rose, A.H.; Lindquist, O.H. 1985. Insects of eastern spruces, fir and, hemlock, revised edition. Gov’t Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977) had noted that severe injury to spruce is unusual, and had been recorded only from a number of locations in Yukon Territory. Levels of damage in the 1992 outbreak decreased at most sites in 1994, and by spring 1995 the outbreak had collapsed. About 15 million ha were affected at the peak. Other outbreaks have occurred in Yukon Territory in 1968 and 1969 (Tripp et al. 1970),Tripp, H.A.; Robins, J.K.; Blauel, R.A. 1970. Alberta–Northwest Territories–Yukon region. Can. Dep. Fish. For., Can. For. Serv., Ottawa ON, For. Insect Disease Survey, Annu. Rep.:84–96. in Connecticut in the early 1970s (Stephens 1985),Stephens, G.R. 1985. A wasp parasite helps control the spruce gall midge. Connecticut Agric. Exp. Sta., New Haven CT, Front. Plant Sci. 38(1):7–8. and in New Brunswick and Nova Scotia in 1981 and 1982 (Magasi 1983).Magasi, L.P. 1983. Forest pest conditions in the Maritimes in 1983. Environ. Can., Can. For. Serv., Fredericton NB, Inf. Rep. M-X-141. Typically, outbreaks have been localized and of short duration. Spruce gall midges overwinter as orange

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e in galled current-year shoots (Felt 1926).Felt, E.P. 1926. A new spruce gall midge (Itonidae). Can. Entomol. 58:229–230. Larvae are about 1.5 mm long when fully grown. The

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

is formed in the larval cell in early spring, often protruding from the cell before the adult emerges. Pupation usually occurs from mid-May to early June, and the 2-winged reddish-brown adult midge emerges through a conspicuous hole in the gall formed in the previous year’s shoot. Mating occurs shortly thereafter, and eggs are laid on the newly developing shoots at the base of the needles (Smith 1952).Smith, C.C. 1952. The life-history and galls of a spruce gall midge, ''Phytophaga piceae ''Felt (Diptera: Cecidomyiidae). Can. Entomol. 84:272–275. As many as 100 larvae per shoot have been reported. Larvae bore immediately into the twig and form cells, the galls forming by the swelling of tissues surrounding the larval cells. Gall formation becomes noticeable within 10 days as a series of small, semi-globose swellings, which render the infected twig twice its normal diameter. Galled twigs usually remain on branches for several years. According to data collected in 1993 and 1994 during an outbreak in Alberta and the Northwest Territories, galled current-year shoots caused by spruce gall midge displayed a negative binomial distribution described by the mean ''kp'' = 5.3333, the variance ''kpq'' = 83.0828, and the dispersion parameter ''k'' = 0.3007. The data were used to derive a sequential sampling plan for the classification of damage cause by spruce gall midge, of use to foresters and pest managers (Brandt 2000). Tiny parasitic wasps usually keep midge populations sufficiently in check to render control measures unnecessary.

References

{{Taxonbar, from=Q20720324 Cecidomyiinae Insects described in 1926