Megaspilidae is a small Hymenoptera

Hymenoptera

Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...

n family with 12 genera in two subfamilies, and some 450 known species, with a great many species still undescribed. It is a poorly known group as a whole, though most are believed to be parasitoid

Parasitoid

A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...

s (esp. of Sternorrhyncha

Sternorrhyncha

Sternorrhyncha is a suborder of the Hemiptera which contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the head...

n Hemiptera

Hemiptera

Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...

), and a few hyperparasitoid

Hyperparasite

A hyperparasite is a parasite whose host is a parasite. This form of parasitism is especially common among entomophagous parasites....

s. Many are found in the soil, and of these, a number are wingless.

The family is distinguished from the closely related Ceraphronidae

Ceraphronidae

Ceraphronidae is a small Hymenopteran family with 14 genera and some 360 known species, though a great many species are still undescribed. It is a poorly known group as a whole, though most are believed to be parasitoids , and a few hyperparasitoids...

 by having a very large stigma in the wing, a relatively constricted metasoma

Metasoma

The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically...

l petiole

Petiole (insect)

In entomology, the term petiole is most commonly used to refer to the constricted first metasomal segment of members of the Hymenopteran suborder Apocrita; it may be used to refer to other insects with similar body shapes, where the metasomal base is constricted...

, and 3 grooves in the mesoscutum

Mesothorax

The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. Its principal sclerites are the mesonotum , the mesosternum , and the mesopleuron on each side...

.