Flowers and veggies lingered in my garden this year, encouraged by the mild autumn weather. Then came the holidays, followed by rain. So much for Fall garden tasks and cleanup chores. Between rainstorms in January, I walked around the garden amazed at how quickly the ground turned from golden fall leaves to a green carpet. As the summer garden died back, weeds took advantage of less competition and filled in the open spaces. They grew from seeds that blew in, were dropped by birds, or were stored in the soil “seed bank' from previous plants that went to seed – just waiting for the right conditions to germinate. Constantly moist soil and cool weather allow seedlings to get their roots established before the soil dries out.

Those beds of weeds are often ignored until Spring weather urges us to get our summer garden started. By then, the weeds are lush and well-rooted. “Weeding” becomes an unpleasant, daunting task if we wait.

Since weeds rob plants of nutrients and provide habitat for unwanted pests, it is important to control them early while they are still small. Although pulling weeds seems like a no-brainer, there is a definite way to do it efficiently. Grab a knee pad, hand hoe, Hori-Hori or trowel, and a big bucket. Kneel at the open edge of a bed and work on the weeds closest to you. Gently pull the largest weeds, lifting the root with a Hori-Hori or trowel. Next, with your fingers, pinch the base of an individual plant and “pluck” the weed out. This loosens the soil around it. making the next plant easier to pull. Gently shake the soil off the roots back into the bed before putting the weed in your bucket. Now, give the cleared area a shallow scuffle with the hand hoe to dislodge small seedlings. Don't dig weeds with a spade or disturb the soil deeper than an inch. This is hard on the soil structure and brings more weed seeds to the surface. Don't get anxious. If you try to grab and pull large handfuls, it only breaks off the leafy tops, which soon regrow from the leftover roots. It's better to do a smaller area thoroughly. Finally, add a 1” layer of weed free compost to the cleared area. This prevents light from germinating new seedlings.

Pulling weeds will give you a chance to appreciate the abundance of slugs and snails as well! It always catches me off guard to see how early the eggs begin to hatch. These voracious tiny babies are everywhere I look. Weeds, as it turns out, are a perfect hiding place to avoid predators. Tucked under the flat rosette of Shepherd's Purse or in the axis of an Asparagus leaf, slugs can eat and grow and not be found. Removing the weeds will greatly reduce their hiding places, as will removing last season's straw mulch and keeping the grass short around the garden beds… But slimy things are persistent in coastal gardens.

The undersides of wilted summer foliage keep snails happy and dry until tastier foliage emerges. They do serve a function, of course. Slowly, they help the decomposition of plant material. Summer plants that have been left to rot give slugs and snails an easy dinner. As I clean the debris and cut back the plants, I have found tiny little snails by the hundreds this year. Cleaning the beds reduces snails, but it also redirects them to the fresh new growth of healthy plants. Although I would love to just leave them for natural predators, there aren't enough birds, snakes, opossums, or other critters to make a dent in this year's bumper crop of mollusks.

There are no sure-fire exterminators for slugs and snails in the home garden. Environmentally concerned gardeners use Iron Phosphate baits like Sluggo with some success. But even the heavy-duty snail baits- the ones that contain Metaldehyde or Carbaryl (that also harms worms, reptiles, birds and some mammals) - only work on the snails that come in contact with the chemical. Many of the small hatchlings emerge and head for a sheltered place above the ground. You'll find them hiding in the tender tops of plants, under the lips of flowerpots, or behind shrub foliage where their ‘foot' never touches the ground. In the cool, damp air of night, they glide from their perch to devour prized plants – which seem to be their favorites. Controlling them becomes a bit more problematic and requires a combination of approaches.

I hesitate to share that hunting slimy slugs and snails has become a bit of a questionably sane, definitely weird obsession for me. You won't find me excited by a dish of beer with a few drunken snails in it. Instead, I clean, prune, plot, bait, consider the possibility of becoming an Escargot farmer, and then become the Human Predator. (That's right -  it's my Super- Power. ) To tackle the problem, I put on the garb of a crazed gardener - a bright LED headlamp, rubber gloves, a container of soapy water - and head into the night garden to make my rounds. As I examine each plant, turning over leaves to check bothsides, I pluck my slow-moving prey and pop it into the container, where it sinks to its demise. It's not a pretty sight. But there are just SO many snails!

As the nights go by and the population dwindles, I marvel at the impact I can have on a single population of slugs and snails. Yes, that's right, “a single population” because there will be more eggs hatching. A single snail can lay 6 batches of eggs in a year with up to 80 eggs each. That's 480 eggs for every snail! It's never-ending. But I'm doing my part.

So, I encourage you to get a head start on the weeding and garden cleanup this year. Keep that cool fashion-statement headlamp handy, and just ignore the neighbors' comments about your new nighttime gardening chore. For what it's worth, I can vouch for your sanity.

 

For additional information about Integrated Pest Management (IPM), including weeds and mollusks, Check out the University of California website  https://ipm.ucanr.edu/PMG/menu.homegarden.html?src=302-www&fr=3723

For help identifying and controlling weeds, https://ipm.ucanr.edu/PMG/weeds_intro.html

For more on slugs and snails, https://ipm.ucanr.edu/PMG/PESTNOTES/pn7427.html

 

All photos are courtesy of the author, Annie Sicotte, and are used with permission.

 

I Can Name That Worm in Four Clues – How About You?

Match the clue to the Worm's Image. Place an X in the appropriate column.

Worm 'A'—Earthworm, nightcrawler, Lumbricus terrestris, is one of over 2,700 varieties of earthworms. They play an important part in the ecosystem, improving the quality of the soil, such as its moisture, ability to hold water, and nutrient content. They are also an important part of composting.

Worm ‘B' – Is a jumping worm, Amynthas agrestis. It is an invasive earthworm capable of harming native forests. This pest devours leaf litter and other organic matter, changing soil texture and nutrient availability to a point where some plants may be unable to survive. Its feeding can lead to a decline in the diversity and population of native plants and other organisms within forests and gardens. If you have seen this worm, go to https://ucanr.edu/sites/hdnmastergardeners/Jumping_Worm/ to report your findings and to learn more.

Resources and Further Reading:

Cornell Cooperative Extension https://warren.cce.cornell.edu/gardening-landscape/warren-county-master-gardener-articles/invasive-asian-jumping-earthworms

UC Statewide Integrated Pest Management https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=56929

University of Minnesota https://jwp.cfans.umn.edu/meet-jumping-worm

Answers:

 

E is for Earwigs - The Cringe-worthy Earwig

For most people, there is something cringe-worthy about the ubiquitous earwig. The name comes from Old English, ?ar-wicga derived from ?ar (ear) and wicga (beetle, worm, insect) and originated from the widespread false belief that the earwig crept into peoples' ears at night and burrowed into their brains. Earwig also means “a person who worms himself or herself into another's favour by whispering and insinuation; a person who seeks to influence others in secret,” “to importune or pester, esp. in private, to influence or bias (a person) secretly; to insinuate oneself into the confidence of (a person),” “to listen covertly to another person's conversation, to eavesdrop” or “to fill the head of (a person) with wild or eccentric notions.”¹  Rather a lot of symbolism for a small brown insect—think Finnegans Wake or Wrath of Khan.

Despite the cringe-factor, earwigs occupy an equivocal place in our pest bestiary. While they can and do ravage vegetable seedlings, mow through annuals, infest budding flowers, and inflict significant damage on soft fruits and corn, earwigs also play a beneficial role by feasting on decomposing vegetation and pests like mites, aphids and other soft-bodied insects.^2,3

The species of earwig found in our gardens is likely the European earwig, Forficula auricularia, which was introduced accidently around 1900. These earwigs commonly damage seedling, soft fruit, and sweet corn. Diagnosing European earwig damage is a process of exclusion. Seedlings may be missing all or parts of theirs leaves or even chewed down to the soil line, stem, and all. Leaves on older plants are often riddled with irregular holes and gnawed at the margins and edges. European earwig damage may look like the work of caterpillars, but earwigs do not leave frass (excrement) webbing or pupae, unlike caterpillars. It resembles the work of slugs, but there is no telltale slime trail. To confirm your diagnosis, go into the garden at night with a flashlight or headlamp and you can see your pest in action.

European earwigs (nymphs and adults) may gouge holes or tunnels into soft fruits, such as strawberries, raspberries, blackberries, apricots, and peaches. These holes can be shallow or extend deep into the fruit. In developing corn, earwigs eat the silks (pollen tubules), which prevents pollination. They also munch on flower buds and flowers. They are versatile and flexible in their diets, and I've found them in everything from artichokes to zinnias.^2,4  Sometimes they are chewing away on the plants, other times they appear to be sheltering and probably other times they are busy eating aphids and other pests. Although I have never witnessed the pest control firsthand, Robert Orpet, PhD has shown that aphids were consumed in apple orchards even when the aphids were rare suggesting that European earwigs may provide biological control. He found no evidence of earwig damage to the fruit.⁵

If your garden is populated largely by lawn, trees, woody ornamental plants or an apple orchard, earwigs are unlikely to give you trouble and may provide benefits.⁶ 

If you are growing vegetables, herbaceous flowering plants, sweet corn, or plants with soft fruits such as strawberries and apricots and suspect that earwigs are causing damage, here are some things you can do.

Reduce outdoor hiding places by eliminating dense undergrowth around your plants, remove debris, from planting areas, store flowerpots, garden decorations and other structures that can provide refuge for earwigs, check your mulches to see if earwigs are hidden in them and remove them if necessary.

Trap earwigs using rolled newspapers, short lengths of bamboo or hose on the soil near plants at dusk. In the morning, pick up these items and tip the earwigs into a container of soapy water. People have also recommended using an empty low-sided tuna or cat food can with oil to trap earwigs—I have tried this but have only attracted cats, possums, and racoons so far. Other gardeners I have spoken to up here on the North Coast, like veteran Master Gardener Grant Eberly, have not found this effective either. You might have better luck. Earwigs are most active at night, and usually congregate in cool, dark moist places during the day. You can earwigs to your nightly pest patrol and let them join the slugs you pick off your plants in a pot of soapy water. You can also reduce the surface moisture in your garden by using drip irrigation. All these steps will help reduce earwig populations to more manageable levels.

Before we leave earwigs, I want to argue that they are more interesting than awful. First, unusual among insects it is easy to distinguish males and female—males have curved forceps-like appendages (technically known as cerci) and females are straighter. They use these appendages primarily in their rather involved courtship (!) and in defense.

Second, female earwigs are rather dedicated mothers. They lay 50-90 eggs in a chamber in the ground each fall. Earwigs may dig as deep as six feet underground in cold parts of the country to escape winter temperatures. While in the nest, females guard and tend their eggs and young. Maternal care is important for earwig offspring. Microbes in nest threaten the eggs and young (nymphs). Maternal care in the European earwig includes defense against fungal exposure, by grooming the eggs and by transferring chemicals that reduce fungal infection. ⁷ Females also care for the nymphs, with post-hatching maternal care lasting through the first two instars or molts. Mothers groom their offspring and provide food for nymphs by regurgitation, much like birds. Interestingly, when nymphs are deprived of maternal care, the orphaned females abandon their offspring for longer periods and feed them less.⁸ While I doubt earwigs will end up on Mother's Day cards any time soon, maternal care appears to be the norm among all earwig species studied—a behavior that is very unusual in an insect that is not social like bees and ants. Next time you see an earwig, consider—she might be someone's devoted mother.

SOURCES

1. Oxford dictionary of English. (Oxford University Press, 2010).
2. Flint, M. L. & Fayard, M. L. Earwigs Management Guidelines--UC IPM. (University of California Cooperative Extension, 2012).
3. Flint, M. L. Pests of the garden and small farm: a grower's guide to using less pesticide. (University of California, Agriculture and Natural Resources, 2018).
4. Coates, W. W. et al. European Earwig: Apricot Agriculture: Pest Management Guidelines UC Statewide IPM Program (UC IPM). UC IPM Pest Management Guidelines: Apricot https://www2.ipm.ucanr.edu/agriculture/apricot/European-earwig/ (2014).
5. Orpet, R. J., Goldberger, J. R., Crowder, D. W. & Jones, V. P. Field evidence and grower perceptions on the roles of an omnivore, European earwig, in apple orchards. Biol. Control 132, 189–198 (2019).
6. Earwigs--Quick Tips. Quick Tips http://ipm.ucanr.edu/QT/earwigscard.html (2019).
7. Boos, S., Meunier, J., Pichon, S. & Kölliker, M. Maternal care provides antifungal protection to eggs in the European earwig. Behav. Ecol. 25, 754–761 (2014).
8. Thesing, J., Kramer, J., Koch, L. K. & Meunier, J. Short-term benefits, but transgenerational costs of maternal loss in an insect with facultative maternal care. Proc. R. Soc. B Biol. Sci. 282, 20151617 (2015).

 

Image Male earwig in flower—photograph by Keyt Fischer, permission to use granted

Image Earwig maternal care photo source: https://commons.wikimedia.org/wiki/File:Nesting_Earwig_Chester_UK_2.jpg Citation: A nesting earwig. © Nabokov / Wikimedia Commons