Ophion luteus is a species belonging to the large family of Ichneumonid wasps. Often called a short-tailed ichneumon wasp, it is a common insect that many people encounter without realizing its identity. It is particularly noticeable in and around homes during late summer and autumn evenings, often appearing at windows or inside rooms after dusk and sparking curiosity.
Identification and Distribution
This wasp has a slender, yellowish-orange body that reaches a length of about 20 millimeters. The abdomen is curved and compressed. One of its most prominent features is a pair of very long, thread-like antennae that are in almost constant motion. Its head is characterized by very large, black eyes, which are adaptations for its nightlife.
The geographic range of Ophion luteus is extensive, as it is a widespread species throughout the Palearctic region, which encompasses Europe and parts of Asia. It has also been introduced in other parts of the world. Its adaptability allows it to thrive in a variety of habitats, including woodlands, agricultural fields, parks, and suburban gardens.
Nocturnal Behavior and Life Cycle
The activity of Ophion luteus primarily occurs after sunset. Its attraction to light is a key part of its nocturnal behavior, as it navigates and searches for both mates and hosts for its young. This is why it is observed near porch lights and windows, particularly from August to September when the adults are most active.
The life cycle is dependent on other insects, specifically the caterpillars of certain moth species. The female wasp seeks out a host, often the larva of a noctuid moth like the Heart and Dart moth (Agrotis exclamationis). Using a specialized organ called an ovipositor, she deposits a single egg onto the caterpillar. The wasp larva develops by consuming the caterpillar from within, leading to the host’s death as the larva matures.
Relationship with Humans
A common question is whether this insect poses a threat. Ophion luteus is not an aggressive species and does not have a defensive stinger like social wasps or bees. The structure at the end of the female’s abdomen, often mistaken for a stinger, is her ovipositor.
This organ is adapted for laying eggs on soft-bodied caterpillars and is not designed as a weapon. While the wasp is not venomous, the sharp tip of the ovipositor could cause a slight prick if the insect were handled roughly. However, such an occurrence is rare, as the wasp’s primary reaction when threatened is to flee. It is considered harmless to humans, and its presence is a sign of a healthy local ecosystem.