EPPO Alert List – Contarinia pseudotsugae (Diptera: Cecidomyiidae)
Douglas-fir needle midge



Contarinia pseudotsugae (Diptera: Cecidomyiidae) is one of three North American species of needle midge (C. pseudotsugae, C. constricta, C. cuniculator) which can attack Pseudotsuga menziesii (Douglas fir) trees and cause some damage. Its presence in several European countries is suspected (species identity remains to be confirmed). In addition to C. pseudotusagae, the presence of C. cuniculator has very recently been suspected in the Netherlands. In these EPPO member countries, as larvae only could be recovered from P. menziesii, a more definitive identification is awaiting the collection or rearing of adult flies. Nevertheless, the EPPO Secretariat considered that the possible presence of new forest pests in the EPPO region should be brought to the attention of the NPPOs. For the moment, only C. pseudotusagae is included on the EPPO Alert List but other Douglas fir needle midges might be added later depending on the results of species identification.



Until the reports about its possible presence in Belgium, the Netherlands, Germany and France which were made in 2015/2016, C. pseudotsugae (as well as its related species, C. constricta and C. cuniculator) was only known to occur in North America.
EPPO region: Belgium, France, Germany, Netherlands. All records are awaiting a final confirmation of the pest identity.
North America: Canada (British Columbia), Mexico, USA (California, Idaho, Michigan, Montana, Oregon, Pennsylvania, Washington). In the USA, it seems that the occurrence of C. pseudotsugae has remained limited for a long time in the Pacific Northwestern part. In the Northeastern part of the USA, it was observed in Michigan for the first time in 2003 and it is considered there as a ‘native invader’ transported by human activities into a new habitat. No data could be found for Pennsylvania, but this US state was not mentioned in the distribution list given by Furniss & Carolin in 1977.



Damage on Pseudotsuga menziesii













All pictures and video were kindly provided by 
Wietse den Hartog (NPPO of the Netherlands)


On which plants

Pseudotsuga menziesii is the only known host of C. pseudotsugae.



Larvae of C. pseudotsugae bore into the needles of P. menziesii and their feeding activity results in the formation of galls. Attacked needles are swollen and frequently bent. Initially, the damaged area is pale in colour, but as the season progresses, it darkens and eventually turns into a reddish to brownish colour. Attacked needles usually fall prematurely. In the USA, damage has occasionally been reported in plantations of Christmas trees, as the presence of the pest could significantly reduce their aesthetic and market value. Heavy infestation can cause severe defoliation and if trees are defoliated for several consecutive years, twig dieback can occur. However, damage caused by C. pseudotsugae is generally not a mortality-inducing factor.


Larva of Contarinia pseudotsugae (identification still tentative)

Damage on Pseudotsuga menziesii – More pictures 

C. pseudotsugae has one generation per year. It overwinters as larvae in the soil under infested trees. In early spring, larvae pupate and adult midges emerge from the soil to mate and females lay eggs in the needles of the expanding twigs. Eggs hatch within a few days and larvae bore into the needles, feeding on them throughout the summer. In autumn, larvae drop from the needles to the ground, leaving a small triangular exit hole. In the USA, it is reported that C. pseudotsugae populations fluctuate widely from year to year.
Adults are small, orange flies (3 mm long). During the emergence period, they can be observed resting on the tips of the needles. Females can be distinguished by their long ovipositor with which they probe between bud scales and into partially opened buds. This elongated ovipositor enables the female to lay long, narrow, orange-coloured eggs in protected areas. Adult life span is short (male: 1-2 days – female: 2-4 days).



Adults can fly but no data is available about their potential for natural spread. The origin of the outbreaks detected in the EPPO region (if confirmed) is unknown. Over long distances, trade of infested T. menziesii could cause pest spread.



Plants for planting, cut branches (including Christmas trees) of P. menziesii, soil from countries where C. pseudotsugae occurs.


Possible risks

T. menziesii originates from the west coast of North America, but has been planted in the EPPO region for timber production and reforestation on a large scale. It is considered that it is now the economically most important exotic tree species in European forests. It is also planted for ornamental purposes in parks and gardens. In North America, C. pseudotsugae is considered as a pest of P. menziesii, in particular in Christmas tree plantations and seed tree orchards where pest control is sometimes necessary. Management strategies against C. pseudotsugae usually involves trapping (emergence traps placed onto the ground near trees) to determine the emergence period of the adults and ensure application of insecticide treatments at the right moment against adults. In forest, chemical control is not considered feasible and the presence of chalcid wasps (unspecified) is reported to regulate pest populations. For the moment, no severe damage has been reported in Europe on P. menziesii in association with Douglas-fir needle midge. The future impacts of C. pseudotsugae (or related species) are difficult to predict for the moment but it cannot be excluded that this pest could present a risk to P. menziesii in forests, nurseries and parks and gardens.


Anonymous (2015) Bilan phytosanitaire 2015. La Lettre du DSF no. 50, 13 pp.
Condrashoff SF (1961) Description and morphology of the immature stages of three closely related species of Contarinia Rond. (Diptera: Cecidomyiidae) from galls on douglas-fir needles. The Canadian Entomologist 93(10), 833-851 (abst.).
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NPPO of Belgium (2015-12).
NPPO of France (2016-12).
NPPO of Germany (2016-04).
NPPO of the Netherlands (2015-12, 2016-04).
O’Donnell J (2010) Predicting and timing of control for Douglas-fir needle midge in Michigan. In: Hart J, Landgren C, Chastagner G (eds.) Proceedings of the 9th International Christmas Tree Research and Extension Conference (Corvallis and Puyallup, US, 2009-09-13/18), 84-87. http://www.iufro.org/download/file/5640/4502/20209-ctre-proceedings-09_pdf/
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Simko B (1982) Douglas-fir needle midge. Determining a spray schedule through use of a midge trap. Ornamentals Northwest Archives 6(1), 8-10. Available on the Oregon State University. Department of Horticulture website. http://horticulture.oregonstate.edu/system/files/onn060108.pdf


EPPO RS 2016/007, 2016/008, 2016/009, 2016/030, 2016/075, 2016/076, 2017/037

Entry date 2016-01