- mid tarsi 4-segmented
- fore-wing uniformly hairy - without any evident bare patches
- body with head and mesosoma (thorax) black, metasoma (abdomen) bright yellow
Catalog Number: USNM
Collection: Smithsonian Institution, National Museum of Natural History, Department of Entomology
Collector(s): R. Smith
Year Collected: 1920
Locality: Twin fall; Florida, Florida, United States
Evolution and Systematics
The wings of one parasitic wasp generate lift by clapping together at the top of a stroke and then peeling off, creating a vortex that provides lift.
"As an example, some types of small parasites, Encarsia, make use of a method called 'clap and peel.' In this method, the wings are clapped together at the top of the stroke and then peeled off. The front edges of the wings, where a hard vein is located, separate first, allowing airflow into the pressurised area in between. This flow creates a vortex helping the up-lift force of the wings clapping." (Yahya 2002:30)
In a flight mechanism called the clap and peel, "the wings clap together and peel apart serially from the leading to the trailing edge. The near-clap and partial peel differs in that the wings approach each other at the top of the stroke, but do not clap together.
"The clap and peel is characteristic of many insects with particularly broad wings, and has been recognized in some mantids and Orthoptera, Phasmida, chrysopid Neuroptera, and butterflies. The radiating veins and flexible cross-veins of the vannus of orthopteroids and dictyopteroids seem particularly to favor the peel, and also the partial peel. The relative breadth of the thorax may principally determine which of the two techniques is adopted: a broad thorax may effectively prevent a full clap.
"The clap itself appears to project a vortex ring, corresponding to a jet of air, and the broad wings of some butterflies at least seem to concentrate this jet by forming a hollow tunnel at the top of the upstroke." (Wootton 1992:127)
Learn more about this functional adaptation.
Molecular Biology and Genetics
Statistics of barcoding coverage: Encarsia formosa
Public Records: 0
Specimens with Barcodes: 5
Species With Barcodes: 1
Encarsia formosa is a species of wasp and a well known parasitoid of greenhouse whitefly. The tiny females (about 0.6 mm long) are black with a yellow abdomen and opalescent wings. There are considerably fewer males than females. They are slightly larger and are completely black in coloration.
Females deposit 50-100 eggs individually inside the bodies of third instar nymphs or pupae of the host species. The wasp larvae develop through four instars in about two weeks at optimum temperatures. Parasitized greenhouse whitefly pupae turn black in about 10 days, while parasitized sweet potato whiteflies turn amber brown. Both are easily distinguished from unparasitized host pupae. Wasp pupation occurs within the whitefly body. Adult wasps emerge about 10 days later.
Use in biological control
Encarsia has been used as a natural pesticide to control whitefly populations in greenhouses since the 1920s. Use of the insect fell out of fashion due to the increased prevalence of chemical pesticides and was essentially non-existent by the 1940s. Since the 1970s Encarsia has seen something of a revival, with renewed usage in European and Russian greenhouses. In some countries, such as New Zealand, it is the primary biological control agent used to control greenhouse whiteflies, particularly on crops such as tomato, which is a particularly difficult plant for predators to establish on.
E. formosa makes use of an unusual form of hovering flight. Unlike normal flight, this method would work in an entirely inviscid medium, as it does not rely on a starting vortex to create circulation about the wing. Instead, the wingtips briefly touch at the apex of their stroke, altering the topology of the surrounding medium.
-  MS Hoddle et al. (1998) Annual Review of Entomology Vol. 43: 645-669
- (http://www.bioforce.net.nz/products/enforce.html) Bioforce Limited, New Zealand
- T. Weis-Fogh, Quick estimates of flight fitness in hovering animals, including novel mechanisms for lift production, J. Expl. Biol. 59, 169-230, 1973
- M. J. Lighthill, On the Weis-Fogh mechanism of lift generation, J. Fluid Mech. 6 0, 1-17, 1973
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