''Cyzenis albicans'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of fly in the family

Tachinidae The Tachinidae are a large and variable family of true fly, flies within the insect order Fly, Diptera, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in t ...

. A parasitoid, it lays its eggs on leaves of oak, maple, birch and other trees, so that when the leaves are consumed by the larvae of the host

winter moth :''In North America, "winter moth" usually denotes the invasive species ''Operophtera brumata'', but may also mean refer to a native species, '' Erannis tiliaria'' (linden looper) or '' Operophtera bruceata'' (bruce spanworm).'' The winter moth ( ...

, the eggs hatch inside the larvae. The fly is native to Europe and Asia but has been introduced into North America as a

biological control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also i ...

agent of the invasive winter moth.

Ecology

''Cyzenis albicans'' is a parasitoid, the female laying its eggs on the surface of leaves which are then eaten by the larvae of suitable host moth species. This fly is synovigenic, continuing to produce and mature eggs throughout its adult life and needing to feed in order to do so. The fly larvae feed internally on the moth larvae, pupating within the moth pupae when their hosts have fallen to the ground, and emerging as adults the following spring.

Hosts

In Europe and Asia, where this fly is native, the larvae of several

geometrid The geometer moths are moths belonging to the family Geometridae of the insect order Lepidoptera, the moths and butterflies. Their scientific name derives from the Ancient Greek ''geo'' γεω (derivative form of or "the earth"), and ''metro ...

moths are parasitised. These include the winter moth (''

Operophtera brumata :''In North America, "winter moth" usually denotes the invasive species ''Operophtera brumata'', but may also mean refer to a native species, '' Erannis tiliaria'' (linden looper) or '' Operophtera bruceata'' (bruce spanworm).'' The winter moth ( ...

''), the northern winter moth (''

Operophtera fagata ''Operophtera fagata'', the northern winter moth, is a moth of the family Geometridae. It is widespread through much of Europe. Geographic distribution This species’ range extends through central and northern Europe to southeast Russia. It i ...

''), the oak nycteoline ('' Nycteola revayana''), the elm autumn moth ('' Ypsolopha vittella'') and the pimpinel pug ('' Eupithecia pimpinellata''). In North American, where it has been introduced, it is only known to use winter moth (''Operophtera brumata'') as a host.

Use in biological control

The winter moth first appeared in Nova Scotia, Canada, in the 1920s. By 1949 it had spread, causing defoliation of trees on a wide scale, and had been identified as a pest species. In 1954 and 1955, several insect species were introduced from Europe in an attempt to control it. The most successful of these were the parasitic wasp '' Agrypon flaveolatum'' and the parasitoid fly ''C. albicans'', both of which became established in Canada. As the numbers of parasites built up, so the populations of the winter moth declined. Winter moths were first noted in the United States in the late 1990s in the state of Massachusetts. During the next decade they spread from

Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...

, south to Martha's Vineyard and Cape Cod, into

Rhode Island Rhode Island (, like ''road'') is a state in the New England region of the Northeastern United States. It is the smallest U.S. state by area and the seventh-least populous, with slightly fewer than 1.1 million residents as of 2020, but it ...

, and Connecticut. There also have been outbreaks of winter moth in coastal New Hampshire and Maine. Winter moth defoliates maples, oaks, fruit trees, and other deciduous trees. Attempts at biological control followed with the release of ''C. albicans'' since 2005. The wasp was considered unsuitable because it is unknown if it is host specific and there are some rare geometrid moths in the area. The fly has become successfully established in Massachusetts, and the level of parasitism of the moth larvae had reached 20-50% by 2015, after thousands of ''Cyzenis albicans'' were released at 17 sites in New England. In its native range, ''C. albicans'' has very little impact on populations of winter moth, and its success in

of this invasive pest in Canada and the United States was difficult to predict; soil conditions seem to have been of importance, and there may have been a dearth of natural enemies to prey on the flies, enabling them to become established. A recent study on the mortality factors affecting ''C. albicans'' puparia in Massachusetts shows that, in fact, ''C. albicans'' experiences heavy mortality from generalist pupal predators and parasitoids.

References

{{Taxonbar, from=Q5201427 Diptera of Europe Diptera of Asia Diptera of North America Insects described in 1810 Taxa named by Carl Fredrik Fallén Tachinidae Diptera used as pest control agents