As I was poking around in the fennel bush looking for aphids, ants, and ladybugs, this reddish creature flew in and crashlanded in a dense tangle of green tendrils in front of my eyes. This bug had a lot of extremities: long antennae, long legs, big wings, very long belly. Getting all its appendages clear of the young fennel was quite a struggle. When it finally managed, it flew off, landing briefly on my forehead. I had no idea what it was, but there’s an app for that! The Seek app from iNaturalist thought it was an Ichneumonid wasp, possibly of the Ophion genus. I checked that against other web sources and it seemed OK. But getting a confirmed ID was another matter. There’s an app for that too! Actually, not an app, but a group of dedicated volunteers with deep bug knowledge who run the BugGuide.net website. I submitted the above photo at 9 a.m. with a request for ID, and had a positive ID the same afternoon. It’s not an Ophion. The genus is Netelia. And it’s a female. The BugGuide expert based the ID on “Presence of an occipital carina, dark-colored ocellar area, scutellum with a lateral carina, propodeum with lateral glymmas, forewings with closed areolet and an ovipositor that projects noticeably beyond the tip of the metasoma.” Translation: the bug has a circular ridge between its mouth and its eyes; the area around its simple eyes on the top of the head is dark; there is a small hard plate with a sideways ridge; the place where the abdomen attaches to the thorax has lateral glymmas (whatever they are); the forewings have a small dark area surrounded by veins; and the egg-laying spike projects beyond the rear end. Identifying bugs at this level requires a whole new language; for diagrams with labels, see this page.
Much remains unknown about these bugs. Wikipedia says:
The Ichneumonidae, also known as the ichneumon wasps or ichneumonids, is a parasitoid wasp family within the insect order Hymenoptera. This insect family is among the most species-rich branches of the tree of life. At the same time, it is one of the groups for which our knowledge most severely lags behind their actual diversity. The roughly 25,000 species described today probably represent less than a quarter of their true richness, but reliable estimates are lacking, as is much of the most basic knowledge about their ecology, distribution and evolution.https://en.wikipedia.org/wiki/Ichneumonidae
The Netelia genus contains about 320 known species. BugGuide advises that for a human to identify the species usually requires dissection of the male genitalia (of the bug, not the scientist). I’m guessing the reason is that the bug’s male genitalia are like a key that only fits a “lock” of the same species. I doubt that the bugs engage in random fit testing with different species before mating successfully. The bugs must have a way of determining a mate of their own species without a lot of embarrassing trial and error. We humans just don’t know what the bugs know. In any event, male genital ID is not a determination that can be made from a photo at this scale. Particularly since this individual is a female.
Whatever species it may be, It’s one of hundreds of Netelia reported to iNaturalist in California, including six in Alameda County. The most recent was reported in June on a trail in the hills above UC by evolutionary biologist Silu Wang. This one is the first reported in Cesar Chavez Park.
Netelia wasps, as noted above, have long stingers. Their main function is to deposit eggs. But the Netelia, unlike almost any other known ichneumonids, can and sometimes do sting humans, causing painful irritation. However, it didn’t sting me.
Ichneumonid wasps generally inject their eggs inside caterpillars of other species. The Netelia females plant an egg on top of a caterpillar. A strong tube attaches the egg to the host, and the larva that grows out of the egg has specialized bristles on its rear end that attach it to the host caterpillar. The larva then uses its mouth to feed on the host, gradually emptying it out and killing it. This is called koinobiont parasitism, as distinct from the idiobiont method, which paralyzes or kills the host immediately. This bug’s lethal method of reproduction has made it an interesting candidate for biological control of other insects, but so far nothing in the way of commercial applications seems to have developed.