The spider wasp Anoplius viaticus, which is about 12 to 14 millimetres big, is relatively widespread in Central Europe. As from April, it already can be found frequently on immature soils marked by scarce vegetation or none at all. Sporadically, it even nests on warm, sunlit forest soils sparsely covered by vegetation.
The following series of pictures illustrates the hard work Anoplius viaticus has done in order to lay a single egg.

To begin with, Anoplius viaticus hectically runs around the ground looking for its prey, a wolf spider (family: Lycosidae), which it usually finds in the latter's lair, for example under a tuft of grass or a piece of wood.

 

After a short, fierce battle it overpowers its prey. It stings the spider with its stinger that is at the end of its abdomen and injects it with a liquid leading to the spider's immediate paralysis.

While the spider wasp now shortly and apparently very nervously surveys the immediate vicinity of its prey, the wolf spider that hast just been overpowered lies narcotized on the earth's surface.

Another female spider wasp of the genus Anoplius viaticus takes advantage of the situation in order to steal the unsupervised prey. But the "landlady" has watched out. A short fight ensues, and while the spider wasp pursues the thief.....

..... an ant finds the fresh, defenseless spider. After it has quickly surveyed it and assessed it as good, the ant decides .....

..... to drag this huge treat that it usually could never overcome by itself to its nest.

But again, the spider wasp is on the scene at the proper time and drives away the ant by assuming a threatening posture.

Now the female wasp tries to drag off the wolf spider lying face down - in vain! The frictional resistance of the massive spider lying on the raw sandy soil is too high.

But than, the wasp alters its tactics: It grabs the spider sideways .....

..... and turns it over without further ado so that it lies in a supine position.

The ant, a fighter itself, does not give in and tries once again to steal the attractive prey. But again, the wasp's aggressive posture puts the ant to rout - this time for good.

Now the spider wasp bends over its prey lying
supine, .....

..... quickly looks at the spider's bottom side .....

..... and encompasses the spider's hips between its last and its penultimate pair of legs.

Than it hauls up the spider and puts it on its silk glands at the end of its abdomen. With the spider hulking up in front of its head, the spider sees no more in front of it. That's no problem for the wasp - now it runs backwards pulling the erect spider in that direction. By means of this mode of transportation, the spider wasp only has to cope with a very small frictional resistance while dragging away the spider, as only the pointed end of the spider's abdomen touches the ground. With the spider "sitting" on the ground, the wasp still does not have to carry its total weight.
The wasp now transports the narcotized wolf spider quite quickly to a rise in the ground, mostly a moss pillow or another small plant .....

..... and drags it up to this place.

The sleeping spider now lies on a leaf at an altitude of about ten centimetres.

After that, the female searches the sandy soil in close vicinity for an appropriate place in order to build its nest. At first, it runs around at high speed seemingly without a plan, scratching here and there. This behaviour may last for hours sometimes. When it has finally settled for an appropriate place, it digs a hole into the soil by scratching and gnawing. In order to confer more pressure to its mandibles while gnawing, it strongly supports itself sideways with its long legs.

Thus the hole gets deeper and deeper.

The sand the wasp has dug up is removed from the nest entrance by alternately using its two front legs while going backwards

From time to time, the wasp returns to the left spider in order to check if everything is all right.

In cool weather, the wasp frequently interrupts its work in order to sunbathe - even if the sun only temporarily disappears behind a cloud. At this, the female wasp presses its body onto the ground thus absorbing the warmth of the floor.

With the wasp continuing its digging, the hole gets deeper and deeper.

Pieces of roots or bigger stones (see picture on the right-hand side) are no barrier for the wasp. They will be grabbed and also dragged away by means of the mandibles.

In this way, the wasp grabs a tunnel that runs obliquely down into the earth and is about ten centimetres long. At the end, it expands to form a small cave, the brood chamber. The sand detached within the tunnel is shoved away backwards by means of its abdomen on whose end a lot of relatively stiff hairs protrude. The abdominal hairiness, which is a perfect means to shove away the sand, is called terminal abdominal hair-brush.
On the earth's surface the sand that has been grubbed out is removed far away from the entrance area (see photo on the left-hand side). This is important a little later, when the wasp intends to pull its prey into the nest.

After the digging is completed, the spider wasp returns to the paralyzed spider and drags it to the nest

It positions the spider next to the nest entrance and surveys the interior and the size of the entrance once again. The last objectionable grains of sand are scratched away.

After all, the female wasp pulls the spider the last few centimetres directly to the nest .....

..... and places it exactly above the nest entrance. Then it squeezes past the spider and enters the nest headlong.

Inside the tunnel, it turns around and returns to the nest entrance where it pokes out its head just a bit, grabs the spider lying ahead by means of its mandibles and .....

.... pulls it into the nest from the inside.

Some minutes later, after the oviposition, the female wasp appears again and starts closing the nest. It bites some sand off the tunnel wall and stuffs it into the nest interior.

The sand that has been removed laboriously some time ago is now partially scratched back and transported into the nest tunnel by means of the front legs.

Now the wasp uses its abdomen in order to harden the loose sand in the nest tunnel. In doing so the female digs its straddled feet powerfully into the ground.

Like a jackhammer the wasp hammers down the loose sand by means of its curved vibrating abdomen.

At the end, it grabs bigger stones or sand boards lying in close vicinity .....

..... and pulls them over the closed nest entrance.

Finally, the nest has been perfectly disguised, and there are no longer any indications of the previous activities.

A look into the inside of the nest shows the tunnel running obliquely. It is about ten centimetres long and ends in the brood chamber. There you can see the caught, narcotized wolf spider on which an egg has been placed.

After a few days, a larva hatches from the wasp's egg and feeds upon the spider. The spider's size exactly suffices so that the larva can pass its development stages. It develops within a few days and subsequently spins a cocoon in which it spends some time as a resting larva. From summer until late summer of the same year, it pupates and hatches as a completely developed wasp soon after. Male and female wasp copulate, the males soon die after that. The fertilized females now dig their winter habitat: a tunnel that is about 30 centimetres long. This time, however, the dissolved soil material is not scratched far away from the nest entrance, but only pushed out of the tunnel, so that distinctive banks of earth are formed - similar to a molehill. On the first warm days in March or April of the following year, the female leaves its winter habitat and immediately starts looking for a wolf spider - the life cycle starts over again.