This week’s insect of the week is a species of the family Megaspilidae. It was collected in a Malaise trap set next to the Lukusi River in Kakamega Forest, western Kenya. Together with the Ceraphronidae, Megaspilidae completes the number of extant families in the superfamily Ceraphronoidea. Ceraphronoidea have greatly reduced wing venation, possessing only a stigmal vein and a very long marginal vein (running along the anterior margin of the forewing). They lack altogether a submarginal vein in the forewing. Together, these three characteristics separate them from the great microhymenopteran superfamilies, Chalcidoidea and Platygastroidea. Also helpful in their identification is the insertion of the antennae very low on the face, just posterior to the oral cavity. For the great majority of ceraphronoid species, the two families are easily told apart by the presence (in megaspilids) or absence (in ceraphronids) of a swollen stigma on the anterior margin of the forewings. In Ceraphronidae the stigma is linear, whereas Megaspilidae have a large, and more-or-less hemispherical, stigma. In the attached image of a megaspilid the stigma is not that obvious because of the angle at which the photograph was taken relative to the plane of the forewing. Both families are moderate in size with ca. 450 megaspilid species and ca. 400 ceraphronids worldwide. Compared with the ceraphronids, the biology of megaspilids is somewhat better known. Some are parasitoids of Coccoidea (Hemiptera, Sternorrhyncha). Other hosts are Neuroptera and puparia of Diptera, and some are hyperparasitoids of aphids through Aphidiinae (braconid wasps).
John Obadiah Westwood (1805-1893) was one of the 19th century’s most important entomologists. He erected the Family Megaspilidae in 1829, one of the 341 taxa he described during a career that lasted 62 years from 1827-1889. He was a close friend of the amateur entomologist and collector sans pareil, Fredrick William Hope. Hope donated most of his vast collection of insects to Oxford on the condition that Westwood would be the curator of the collection, and that Westwood become the first Hope Professor of Zoology at Oxford. Westwood was an excellent artist and was known for the high quality of the figures that accompanied many of the nearly 100 papers he authored. He was among the first entomologists to champion the use of insect parasitoids for the control of pests of agriculturally important crops. Westwood was highly critical of Darwin’s theory of evolution. You can’t be right all the time.