Hornets (Vespa crabro)

A hornet gorging on tree sap

Hornets are huge beasts. The largest European social wasp, hornets are on the wing from April until October, or occasionally into November, and can frequently be seen in the New Forest, flying along woodland rides, across clearings or at woodland edges.

In fact, the New Forest is one of the best places in Britain to see hornets – here the hornet is at the northern edge of its European range, and distribution is primarily in the milder southern English counties.

Hornet flight is often loud, laboured and clumsy. They have a somewhat startling hum caused by rapid beating of the wings, and regularly seem to bump into stems and other obstacles. And rarely do they come to rest for any length of time.

Hornets look, even at a glance, like over-sized common wasps, and that’s not surprising as both species are closely related. Needless to say, however, there are subtle differences in markings and the colours are slightly different: hornets are chestnut-brown and yellowy-orange, rather than the black and yellow of common wasps.

But size is the most obvious distinguishing factor – hornet queens can be 3.5 centimetres (1 ½ inches) long, whilst males and female workers are somewhat smaller.

Yet hornets are usually placid, harmless creatures that ill-deserve their fearsome reputation. Queens and workers have a sting, but not males, and alright, if anybody is foolish enough to stir up the proverbial hornet’s nest, they will likely regret it but given even modest space, and left undisturbed, hornets are unlikely to attack. They’re gentle giants in all senses of the words.

The hornet's fearsome reputation, though, is sometimes their undoing. In parts of Europe, folklore tells that seven hornet stings will kill a horse, three an adult and two a child, so for generations hornets have been mercilessly persecuted by man.

Adult hornets only occasionally take nectar – they prefer sugar-rich tree sap and honeydew from leaves, whilst young queens in late summer also feed on apples, pears and other fruits. Growing broods are fed primarily on pre-masticated day or night-flying insects.

Only young, newly mated queens survive the winter, hibernating in a state of torpor, hidden away in a hollow trees or similarly sheltered place. Warm spring weather, sometimes as late as May, encourages emergence, and a search for a suitable nest site.

Amazingly intricate structures, nests are built of paper made from chewed wood scraped from trees, old fences or whatever else is available. Away from human habitation, they are most often found in hollow trees, so the New Forest’s ancient, unenclosed woodlands offer lots of potential.

Eggs are laid in individual cells arranged in neat, horizontal layers. The larvae hatch after around 6-7 days, are supplied with food by the queen, and after a further 2 weeks pupate; emerging some 2 weeks later as a generation of sterile female workers whose task it is to relieve the queen of further nest building and hunting responsibilities.

She remains in the nest and continues to lay eggs, whilst the workers provide her with food and also feed continually expanding numbers of newly hatched hornet workers.

Hornet males and fertile females - young queens - appear in August, when colonies peak at around 500 insects. The workers cease to feed the old queen, with inevitable consequences, and concentrate on feeding the young queens and males.

Mating takes place in late-August and September, the new queens search for hibernation sites, males and female workers die, and the hornet's annual cycle starts all over again. 

References:
Collins Guide to the Insects of Britain and Western Europe: Michael Chinery
Insects of Britain and Europe: J. Zahradnik and M. Chvala
The Living Countryside – The Renaissance of the Hornet