Spider
wasps are
insects, belonging to the family
Pompilidae. They are solitary, not building communal nests as most other wasp species do. They are hunters, and parasitize
spiders (or other spider wasps) to provide nourishment for their
larvae. Spider wasps are generally non-aggressive to humans, not exhibiting the nest defending behavior of their cousins.
Spider wasps comprise about 290 species in the United States and Canada and about 4200 worldwide, making them a very prolific hunter. Size and coloration among the many species vary. The spider wasp most commonly observed is Cryptocheilus bicolor, a very large wasp at 35 mm in length. The body is a glossy black with orange wings and legs, along with a broad orange band about its abdomen. The wasp holds its wings upright when resting but flicks them rapidly when it runs or hops about. The movements are very rapid, characterized by bursts of motion followed by absolute stillness except for the wing movements, which give the wasp a somewhat jerky style of motion. In comparison to other wasps, spider wasps have extremely long back legs.
A favorite victim of spider wasps are huntsman spiders. These are large, hairy spiders which have a quite threatening appearance while actually being harmless. The wasp attacks the spider, stings it to paralyze it, then deposits an egg on the incapacitated arachnid. The egg hatches and the larva then feeds on the still living spider before pupating in it's silky chamber. The new spider wasp generally doesn't emerge until the following summer.
Often in preparation for the hunt and egg laying, the female wasp will dig a chamber in sandy soil to accomodate her conquest. After acquiring a victim, the female wasp will deposit it within the chamber and seal it. Others bypass this step and simply paralyze their victim, deposit the egg, and proceed on their merry way. A few females will steal spiders from other spider wasps, avoiding the battle for a food supply for their offspring altogether.
The spider wasps sting can cause pain and irritation but is uncommon for humans to experience. Wasps, unlike true bees, can sting multiple times and do not die after stinging. Wasps do not leave their sting in the sting location. As with other bee/wasp stings, individuals will react differently, some with little ill effect, others suffering a more severe allergic reaction. First aid is the same for all such stings. Application of a cold pack can help relieve the pain while more severe reactions should be treated quickly by medical personnel to avoid allergic reaction.
Last summer I was enjoying a little downtime, sitting on my front porch enjoying the sun and breeze.
After a few minutes, I noticed a long, elegant wasp patrolling the lawn. It flew a bit, then landed and ran about, sometimes also hopping. It wasn't long until it flushed a huntsman spider from its motionless attempt at evading discovery. The spider, in comparason to the spindly appearing wasp, was huge. The wasp wasn't impressed by the size differential and set about attacking the spider. The spider tried to fend off the wasp with its long legs while attempting to retreat. The tactic was fruitless. The wasp was an absolute fury, never relenting in its assault on the hapless spider. Finally, the wasp landed a sting, and the spider very quickly became feeble, then immobile.
The spider was too large to fly with, so the wasp grasped it and started dragging it away. The victor and the vanquished quickly withdrew from my sight.
A war had unfolded before my eyes. In the span of 5 minutes the initial engagement had become a pitched battle followed by the absolute defeat of one of the combatants. The amazing part was the battle was total conflict, no fear or hesitation on the part of the wasp, just a simple dedication to vanquishing the spider. I watched that battle with rapt attention, and breathed a prayer of thanks that spider wasps don't come in a 50 pound variety. In that battle I saw a miniature re-enactment of the bug battles of the film Starship Troopers. There was no negotiation, no Geneva Convention rules of engagement, no mercy. There was only war, total war. Mars, god of war, would have been proud.
Sources:
http://www.everythingabout.net/articles/biology/animals/arthropods/insects/wasps/spider_wasp/
http://www.amonline.net.au/factsheets/spider_wasps.htm