The Ichneumon Tribes

Always on the alert for new and interesting creatures perched on the vegetation of Halibut Point I occasionally come across slender, sometimes harlequin-patterned winged insects, often with a conspicuous needle-like appendage protruding to their rear, patrolling leaf surfaces behind their long inquisitive antennae.

Phytodietus burgessi, Ichneumonidae

Something about their proportions is immediately distinctive. They belong to the wasp family Ichneumonidae, a word derived from the Greek for 'tracker.' Ichneumon is also the name of an Egyptian mongoose. They have a common lifestyle of frenetic hunting activity.

Atanycolus sp., Braconidae

The larvae of Ichnemonid wasps become parasites of various other insects. They hatch from eggs inserted by an adult female's ovipositor into a living host that is fated to sustain and eventually succumb to the developing wasp larvae. Here is an example of a free-roaming but doomed caterpillar. In other cases the victim may be paralyzed and dragged to a subterranean nest. The Ichneumonidae play an important role in controlling other insect populations that are harmful to human interests, especially agriculture.

Cocoons of a Braconid wasp in the superfamily Ichneumonoidae
attached to a Sphinx moth caterpillar

Braconids and Ichnemonids are closely related divisions of the superfamily Ichneumonoidae. Within it the Ichneumonid constitutes one of the largest and most taxonomically confusing families in the insect world.

An icheumonid of the subfamily Cremastinae

The Ichneumonidae comprises dozens of sub-families just in North America. These are informal taxonomic categories for organizational convenience. Sometimes it's not possible to make a more precise assignment than sub-family from field photographs. Subfamily names end in the suffix -inae.

An icheumonid of the tribe Gravenhorstiini, subfamily Anomaloninae

Similarly, TRIBE is an informal taxonomic category falling between subfamily and genus. Tribe names end in -ini. As one authority put it, "Basically we could say that a tribe is a group of organisms among which the differences are extremely minor but still noticeable."

Acroricnus stylator aequatus, tribe Cryptini,
identified to species level

Classifying the members of the biological world into various taxa reflects the desire of human beings to group the great diversity of living and extinct organisms into natural categories. The organizational level TRIBE comes in handy for complex families like Ichneumonidae.

Ichneumon annulatorius, tribe Ichneumonini

When a wasp is this conspicuously marked it can usually be assigned at least as far as one of the ichneumonid tribes. However a very similar photo I submitted for identification failed to show the wing venation pattern as clearly, so genus and species confirmation were withheld by BugGuide experts.

Ichneumonids generate names among taxonomists as colorful as their appearance and life histories. Some of the lexicon is drawn from classical myth and language. Ichneumon annulatorius, pictured above, means "The Canceller." Other species in my local gallery are termed obstinator (besieger), paratus (ready), inquisitorius (investigator), ultimus (final).