(Background: this essay was one of several columns commissioned for the magazine Gothic Beauty between 2009 and 2011. Since the magazine hasn’t published a new issue in years, it’s time to drag up a few of these old columns so they can find a new readership.)
Dedicated to Steve Bissette, who helped me get on this odd path in the first place
Most typical garden books and sites include at least a thumbnail guide to beneficial and destructive animals that may visit, inhabit, or infest a garden area. After describing and illustrating the usual pests (whitefly, stink bugs, grubs) and the usual overly cutesy garden helpers (honeybees, earthworms), the typical garden writer is at a bit of a loss. This is a shame, because some of the ignored critters are the most interesting.
Let’s take a look at my new garden area, and note the animals that don’t make the usual “friends of the gardener” lists. I have lots of visiting birds, including both red-tailed hawks and Harris’s hawks that pick off overly unobservant mourning doves and bluejays. (I’d also like to mention that while years of Disneyfication of garden critters make hummingbirds out as “cute”, this comes from people who’ve never dealt with them. Hummingbirds have no fear of man, beast, or god, and there’s a very good reason why the Aztecs considered them avatars of their war and sun god Huitzilopochtli. I’ve seen hummingbirds challenge crows and hawks and win, and they’ll gleefully take on humans that get too close to their nests.) Besides praying mantises, there’s also the wheel bug (Arilus cristatus), a determined predator so named because it appears to have a watch gear jammed into its back. I have anoles (Anolis carolinensis) during the day that camp out on the trees in the back yard and flash their dewlaps at each other, and introduced Mediterranean geckos (Hemidactylus turcicus) that sing to each other all night. I have spiders and beetles and glowworms, grass and garter snakes, and any variety of natural decomposers such as worms and sowbugs. I’m not even going to start with the great horned, barn, and screech owls that buzz the house at night, or the plethora of Mexican free-tailed bats, or the great blue herons that fly over the neighborhood at dusk like misplaced pterosaurs.
The one set of regular travelers that are always welcome in my garden, though, are the ones that most gardeners try to drive off. Even the biggest advocates of organic gardening grab a swatter or a spray can when they see one of these, and they go berserk with rolled-up papers and brooms in pointless attempts to drive them away. Even mosquitoes only warrant repellent when their presence becomes too extreme, but any grocery store or garden shop has can after can of spray intended for my visitors, all promising to kill them dead from as much as 30 feet away. Not only is this an irrational response to one of the best beneficial organisms you can get in your garden, but it’s almost completely without merit. I’m talking about wasps.
Wasps are members of the insect order Hymenoptera, an order they share with their cousins (and possible descendants) the bees and ants. Wasps range in size from microscopic to the size of sparrows. Many species are social, such as hornets and yellowjackets, where they live in colonies of dozens or even hundreds of related individuals. Others are completely solitary. Both males and females subsist on nectar and other sugary liquids (the reason why wasps always show up around spilled fruit juice and soda), but only the female has a modified ovipositor that it can use as a sting for defense. Best of all, as far as the garden is concerned, most species are considered “parasitoid”, where they spend the first part of their life cycle feeding off a host. Each species of wasp has one particular host arthropod it uses as a host, and that list includes bees, flies, cicadas, spiders, tarantulas, and even praying mantises.
Social wasps, such as hornets and various species generally lumped together as “paper wasps”, capture small prey such as caterpillars, masticate them with strong mandibles, and then feed the mush to their young. As such, they’re very valuable predators. Others go through a much more fascinating and disturbing process. Many species fly to a host, lay eggs on or in the host, and then let the hatchlings feed upon the host’s body from within, ultimately killing it. Still others capture their prey, paralyze it with carefully measured stings, and return it to a bolthole or gallery. There, the mother lovingly places an egg in a particular location on or near the victim, seals up the space, and lets the youngster go through a complete metamorphosis from larva to pupa to adult.
Anyone studying wasps tends to use analogies from the Alien films to describe their reproductive behaviors: the larvae do feed on living hosts, and they emerge to metamorphose into beautiful and terrifying adults that capture new victims to continue the life cycle. It’s just that the fictional analogy is lacking compared to reality. For instance, picture a remake of Alien with Kane having three or four chestbursters ripping free, only to spend the next few weeks frantically guarding them as they pupated. The wasp genus Glyptapanteles does something much like this, where as many as eighty larvae emerge from one caterpillar and spin cocoons: the caterpillar remains by the cocoons and violently repels anything attempting to disturb them. Likewise, Aliens might have been even more horrifying if Apone and Dietrich had been stung in the head and then led willingly into the alien hive. The emerald cockroach wasp Ampulex compressa does just that to captured roaches. You have wasps that infest aphids, ones that capture big insects like cicadas and bury them in carefully dug galleries, and even make containers of mud and pack them full of paralyzed spiders. (For the record, the common mud dauber wasp Sceliphron caementarium is the main predator of black widow spiders.) The tarantula hawks, genus Pepsis and Hemipepsis, paralyze and take off with big ground spiders, hence the name, and one group even uses adult praying mantises as hosts. (In his book The Hunting Wasp, John Crompton compared this behavior to a mother deciding that the only food in the world good enough for her children was grizzly bear. Many times, the wasp loses the battle.)
The horror doesn’t stop there. Many other wasps parasitize the eggs of other arthropods, such as the nearly microscopic wasps that carefully drill into mantis egg cases and lay their own eggs therein. Other wasps modify the DNA of host organisms: the huge variety of plant galls are caused by wasp eggs that actually modify the surrounding tissue to form protective cases. Every time you eat a fig, you’re eating the end result of a very complex and disturbing life cycle involving the fig flower and one particular wasp, and if the wasp becomes extinct, so will the fig. Some wasps, such as the wingless ones known as velvet ants, live as cuckoos for other wasp species, laying their eggs on hunting wasp hosts and letting their young eat the hunting wasp eggs before they hatch.
Even without this, wasps are fascinating and underappreciated creatures. Fear of wasps is learned, usually due to parents who themselves were taught to fear wasps, usually way out of proportion to the actual pain of a sting. (I’m severely sensitive to bee stings, to the point of nearly needing hospitalization after one good bout as a beekeeper, and I’m amazed at how little a typical paper wasp sting actually hurts. For fun, look up the Justin O. Schmidt Pain Index for a useful and irreverent guide to the actual pain caused by many species.) While most wasps can be very territorial around nest sites, the allegedly aggressive flight patterns of many big wasps is actually caused by simple curiosity, and I’ve surprised friends and family by holding still, letting a wasp big enough to fly off with small birds make two or three passes around me, and then watching it buzz off once it’s satisfied that I wasn’t a threat. More often than not, individuals are stung in attempts to kill wasps, so the lesson is simple: DON’T TRY TO KILL THEM.
Like Gila monsters, Australian brown snakes, and snapping turtles, wasps have an insanely overwrought reputation for mayhem and menace. Stop for a second, put down the can of Raid, and watch wasps for a little while. I did the same a decade ago, and now anyone dumb enough to spray them in my yard is going to get more than angry wasps on their asses.
Reference
Shamefully, the literature on hunting wasps is very thin outside of scientific journals (even Carl Zimmer’s fascinating book Parasite Rex only contains a tiny bit on wasp parasitoid habits), and the two best available popular books are well over forty years old. That said, both are still fascinating reading.
The Hunting Wasps by Jean-Henri Fabre. 1919, Dodd, Mead, 432 pp. Although sadly neglected today, the French naturalist Jean-Henri Fabre was an inspiration to entomologists throughout the early Twentieth Century for his careful observations of insect life. The Hunting Wasps goes into detail on Fabre’s firsthand excavations and experiments with both the wasps and their hosts. (If you read French, go for the original: the English translation is exceptional, but I understand it’s still missing much of Fabre’s passion and humor.)
The Hunting Wasp by John Crompton. Lyons Press, 255 pp., ISBN 978-0941130493 At times both irascible and awed, John Crompton’s 1955 book is still without peer on the subject of hunting wasps. Very much written as a popular account, it may be outdated purely due to scientific advances, but it still rates as one of the best books on wasps ever written.