Hymenoptera

Hymenoptera are insects with two pairs of membranous wings, in contrast to diptera, or flies, which have only one pair, and butterflies, which have two pairs of scaled wings.

Two images reveal the high evolutionary complexity of hymenoptera, presenting us with four hymenoptera belonging to two major branches. In the first photograph, there are two aculeates, or social hymenoptera, a hornet, specifically Vespa orientalis, capturing a bee (Apis mellifera of the Apis syriaca race) in flight as it exits its hive. The hornet carries the bee back to its own nest to feed its larvae. In the second photograph, we are on the side of Symphyta, where a wasp of the Asaphes genus is seen inserting its ovipositor into a mummified aphid inhabited by another endoparasitoid wasp larva, most likely Aphidius ervi, which feeds on the aphid and whose larva will, in turn, be nourished by the Asaphes larva. Here, we have a case of ectoparasitism (the parasitic egg is laid on the prey) of an endoparasitoid (the parasitic egg is injected into the prey).

These two examples demonstrate the high complexity of hymenoptera, which can be considered an “evolutionary pinnacle in the class of insects” (Andrew Austin and Mark Dowton, Hymenoptera. Evolution, Biodiversity and Biological Control, p. 4).

This makes hymenoptera one of the dominant forms of animal life on Earth, both in terms of the number of species (> 115,000 according to Austin and Dowton) and the diversity of ecological niches and lifestyles. This order comprises the majority of social insects (ants, bees, wasps, and hornets) and parasitoids that feed on aphids (aphidoidea), as well as arachnids and other insects (diptera, lepidoptera, or even other hymenoptera).

The social or parasitic interactions of hymenoptera are not only numerous with other animal species but also with humans, as attested by Ian Gauld to Barry Bolton. I quote:

“Both economically, aesthetically, and biologically, there are few groups of animals as important to humans as Hymenoptera.”

Economically, some species are beneficial. Anthophila (bees) are crucial for agriculture as pollinators, a role also performed within Apoidea by wasps that, as adults, feed on nectar, such as Isodontia splendidula, a sphecidae family member often seen foraging on thistles in the Bekaa Valley. Even though they also hunt small insects that they paralyze to feed their larvae.

The species for which humans have the oldest appreciation is the only bee that overwinters in the form of a colony, Apis mellifera, from which various products are harvested: honey first, followed by pollen, propolis, and even the wax that forms the honeycombs.

Sub-orders

Apocrita vs Symphyta. Apocrita are Hymenoptera endowed with a wasp waist, whereas the Symphyta, or sawflies, have a broad connection between the thorax and the abdomen.

Aculeata vs Parasitica. Among Apocrita, some have the reproductive organ called ovipositor that evolved into a stinger. Numerous Aculeata are eusocial insects, whereas Parasitica encompass all parasitoid wasps.

Vespoidea vs Apoidea. Vespoidea possess a petiole at their waist, whereas bees do not.

For the latter, read the page dedicated to the bees of Lebanon. And we dedicated two pages to Vespoidea, one on the wasps of Lebanon, another on the ants of Lebanon.