The gentle giant

European Hornet

I’ve been holding on to this subject for a little while, always having something else lined up or that I came across that I ended up talking about first, but I’ve been wanting to post it. Yesterday and today we had guests up, so I didn’t get a chance to take many other photos, which meant this was a great opportunity to sneak this one in.

Not long after our arrival here we started noticing these GIANT, MONSTEROUS wasps coming to the porch lights at night. So large, in fact, that wasp wasn’t the first insect that came to mind when we looked at them. It took me actually catching one, and chilling it in the fridge, to get a good look at it and confirm that it was, indeed, a wasp. A little nervous to even put my hand anywhere near the thing, I was very careful to take my photos quickly, while it was still sluggish from the fridge, and using a pencil for scale rather than my fingers like I often do.

European Hornet

My first thought was a cicada killer, a type of native wasp that is similarly giant. But the markings weren’t right for cicada killer (and I looked at quite a few pictures, feeling at a loss for whatever else it might be). Eventually it took doing a search on BugGuide.net for “giant wasp”. That turned up a good number of hits; cicada killers, of course, but also my wasp. Turned out, it’s a European Hornet (Vespa crabro), the largest species of the hornet family, and an introduced species, originally native to Eurasia. It was introduced to New York sometime around 1840, and has become well established in woodlands and forests through much of the east.

Fortunately, these hornets are a fairly peaceful species. Sure, they sting, as do all hornets, but it requires some specific provocation, they aren’t aggressive simply to one’s presence. This proved true as we would go out to check out the moths and other insects coming to the lights, none of the hornets ever seemed even the least bit interested in us, although their heavy, loud buzz was still a little off-putting. The hornets are attracted to artificial light on summer evenings, not unlike many species of ichnumonid wasps and sometimes other types of wasps as well. BugGuide.net suggests they may be seeking prey, but the ones I observed didn’t seem to show much interest in the other critters at the light.

European Hornet

The nests the wasps build is a one-time-use-only structure. They nest in hollow trees, or sometimes in attics, which are a decent approximation of a hollow tree if the real thing is not abundant. Like the yellowjackets, another type of hornet, they build paper nests, which reach peak size toward mid-September. They can attain quite a large size by the fall. The queen in the nest then lays special eggs that develop into the reproductives – the new queens and males – which engage in a nuptual flight. The old queen, and the males once they’ve mated, all die, but the new queens find nooks and crannies in which to hibernate for the winter.

In the spring, the new queens emerge and find a suitable spot for a new nest, and get started on building the paper cells. She lays a few eggs in these cells, and provisions the larvae with insects herself. Eventually they mature into sterile female workers, who then take over the duties of building the nest and caring for the larvae, while the queen goes about laying more eggs.

While the larvae are fed insects, the adults feed on nectar and sap, which is high in sugar, providing energy for powering flight. In addition to this, the larvae are able to secrete a sugary liquid, which the workers also use to supplement their food.

European Hornet

Like most insects, the adults have large, compound eyes, and three ocelli on the top of their head. The compound eyes are primarily used for detecting movement and discerning shapes that are useful in navigating and finding nectar sources. The ocelli are primitive eyes that are only really useful for detecting light and dark (something the compound eyes aren’t good at), which helps the wasps stay upright relative to the ground, and also helps in determining day length, etc. It may be that the insects use one or the other of their two sets of eyes to navigate by the sun, and the artificial lights at night confuse this sense.

You can also see well here the large, powerful jaws that the adult uses for catching and dissecting its prey. They’re not used for eating, since the adults don’t eat solid food themselves, but rather for handing the insects that are taken back for the larvae to feed on.

European Hornet

I love close-ups of insect feet. Wasp and hornet feet (as well as many other insects) are neat because they’ve got little spurs at each of the joint, and two long claws at the tips of the foot. It’s these claws that allow them to climb up vertical surfaces, or even to hang from the ceiling, finding little imperfections in the surface that we can’t detect.

European Hornet

The wasp I caught takes a moment to clean her back legs by rubbing one along the length of the other. Her stinger is usually kept retracted unless she’s planning on using it, so it’s not visible here. Given their size, one would expect the sting of this species to hurt like an expletive, but it’s less painful than bee stings. This is because the stinger of the bee is pulled from the abdomen and continues pumping venom into the victim beyond the initial attack, while wasps, since they need to be able to use their stinger repeatedly when collecting prey insects, only inject a relatively small amount. Blackburnian got stung by one when he was trying to remove it to outside (he made the mistake of swatting it), and it barely swelled up or got sore. Their threatening appearance and old wives’ tales regarding the potency of their sting have resulted in the species being persecuted through much of its native range, however, and there are regions within Europe where the hornet is now endangered.

She’s presumably one of the sterile female workers, as the new queens wouldn’t be flying yet by then. Even with the ordeal of being captured, stuffed in a fridge overnight, and then asked to pose for the camera, she was very well-behaved. The only time she showed any reaction was when I pushed the pencil tip up next to her. Even then, she reared back with her front two legs in the air, paused for a moment to assess the threat, then, deciding it was benign, continued walking along the deck railing. Sure are fearsome looking critters, but really they’re just gentle giants.