Extension Master GardenerSM Volunteers of Buncombe County

Plant Insects

The Garden Detective: What’s the White Fluff on My Serviceberry Tree?

Q:  My serviceberry tree has white fluff under some of its leaves! The affected leaves turn orange and then drop off. Help! What should I do to prevent whatever it is from damaging my tree any more than it already has?

Serviceberry tree_Amelanchier arborea_Rosaceae_Kerry Woods_CC BY-NC-ND 2.0_Flickr
Serviceberry tree

A:  When it comes to garden problems, it’s best to do a little sleuthing before taking any action.

Our “victim” is a serviceberry tree (Amelanchier spp.). In western North Carolina, this early spring bloomer with delicate white blossoms and beautiful early summer berries is a welcome addition to any garden or forest-scape. After its blooms provide bees and other insects with nectar and pollen, its fruits are a favorite of birds and mammals—from chipmunks to bears, as well as people! 

The possible culprits? Like Miss Marple (who is an enthusiastic fan of lovely gardens), we’ll start with what we know. To figure out likely attackers, we turn to Extension horticulture experts! Serviceberry is subject to several insect pests, including pear sawfly, borers, and oystershell scale that don’t match the description. There are pests and diseases from which to choose. Could it be two-spotted spider mites? Or how about lacebugs? Powdery mildew is a common disease of serviceberry—how about that? With so much information available, it can be challenging. 

The local “detective” team. It’s time to visit the Extension Master Gardener HelpLine at the Buncombe County Extension Office, 49 Mt. Carmel Road, Asheville, NC.

The solution. Looking under a microscope at an affected leaf reveals the pest’s true identity: woolly aphids! These handsome little critters look like they are festooned in white feathers. But looks are deceiving. In reality, woolly aphids are covered in waxy strands that make them impervious to insecticidal soap or contact insecticides. Like other aphids, these pear-shaped insects suck sap from plant leaves using their needle-like mouthparts.

 What to do? NCSU Cooperative Extension Hoke County Center notes that “lacewings, lady beetles, and parasitic flies normally keep woolly aphid populations below numbers that rarely damage trees. Try to tolerate damage or presence on trees and shrubs. Populations of woolly aphids rarely get to levels that harm plants despite the appearance of distorted leaves.” So, removing and bagging the affected leaves is all that is needed at this point!

More about serviceberry
Before we close this case, there is one more mystery. Where did the name serviceberry come from? George Ellison writes in the 10 April 2013 edition of Smoky Mountain News:

“Retired Western Carolina University botanist Jim Horton notes in The Summer Times (1979): “Several explanations are advanced for the common name serviceberry … The most interesting, though not necessarily the most accurate, holds that the tree blooms during ‘service’ time; the time when old-timey itinerant preachers were first penetrating the mountains after the spring thaw and performing services…

“In A Natural History of Trees of Eastern and Central North America (1950), naturalist Donald Culross Peattie, who lived for awhile during the 1930s near Tryon, notes: ‘It is from the fruits that the Sarvissberry takes its name, for the word is a transformation of the ‘sorbus’ given by the Romans to a related kind of fruit.’”

Whichever theory you choose to accept, one thing is certain: Amelanchier arborea is a garden favorite!

Article written by Janet Moore, Extension Master GardenerSM Volunteer.

Learn more
Woolly Aphids Present Sticky Situation
University of Kentucky

A Dilemma: “Weed” or Pollinators’ Best Friend?

No, this poster is not an advertisement to plant more thistles! As part of a class on the need for pollinator habitat, it provoked questions and the rethinking of some old ideas.

Thistle_weed or pollinator forage
Thistle

A patch of any kind of flowers covered with bees and butterflies is a bit like a soda fountain or candy counter jammed with kids. Pollinators choose flowers that are close by, abundant, and shaped so their tongues can reach the rich reward inside—nectar! Flowering weeds—what we gardeners sometimes define as a “plant out of place”—fit all these requirements. And so, pollinators discovered the virtues of flowering weeds millennia ago.

Maybe it’s time to take a new look at your lawn and garden weeds, through the lens of these creatures who are responsible for so many of the fruits, vegetables, nuts, seeds, and oils we eat. Maybe you, too, will discover the virtues of weeds already valued by our pollinators.

What pollinators need
All 4000 native bee species, as well as imported honey bees, depend on flowers for food! They get carbohydrates from the sugary nectars and proteins and fats from flower pollen. Moths and butterflies also require the foliage of specific host plants, in addition to their flowers, to provide food for their hatched butterfly and moth eggs. 

Flowering spring “weeds”
With the arrival of spring, early-emerging solitary bees, such as the mason bees, go to work pollinating berries and tree fruits. Mated bumble bee queens are coming out of hibernation to begin nest construction and egg laying. Perennial honey bee colonies build up their populations from the 10,000-strong winter clusters to mighty summer-foraging forces of 50,000 or more!

Many winter- and early spring-flowering weeds provide these pollinators much-needed food when little else is in bloom. Purple deadnettle (Lamium purpureum), henbit (Lamium amplexicaule), and dandelion (Taraxacum officinale), for example, are important nectar and pollen sources.

Flowering fall “weeds”
Fall is an equally busy feeding time for our pollinators. Wasps and hornets seem to know that their nests will soon be empty. Bumble bees are rearing queens. Honey bees are filling hives with honey they will need to survive the winter. They’re also rearing important winter bees with special fat body glands that are repositories of nutrition for babies that will hatch after the winter solstice.

Fall-blooming asters (Symphotrichum spp.), goldenrods (Solidago spp.), Joe Pye weed (Eutrochium ssp.), and ironweed (Vernonia, spp.)—all native plants that are often treated as weeds—provide significant staples at a time of frantic pollinator feeding when other blooming plants are in short supply.

Honey bees on butterfly weed
Honey bees on butterfly weed

A special note on butterfly weed vs. butterfly bush
Ironically, the plants with “weed” in their common names, milkweed and butterfly weed (Asclepias spp. and A. tuberosa), are the essential host plants required for Monarch butterfly reproduction. But, the foliage of butterfly bush (Buddleia spp.) is of no value to any moth or butterfly in the United States. Yes, butterfly bush flowers provide nectar, but the plants escape our landscapes and show up unbidden in the wild as plants out of place!

Is your landscape a food desert to pollinators?
Or does it include a smorgasbord of useful, attractive flowering plants? Adding native flowering annuals, perennials, vines, shrubs, and trees to your yard will provide foliage for butterfly and moth larvae, as well as flowers for all pollinators. In your lawn, white clover (Trifolium repens) blooms provide nectar in summer (and as a bonus, clover along with your grass clippings may put enough nitrogen back into the soil to fertilize your lawn). Richard Orlando, in Weeds in the Urban Landscape: Where They Come From, Why They’re Here, and How to Live with Them, notes that other low-growing flowering plants, such as thymes (Thymus spp.) and self-heal (Prunella vulgaris), are lovely and useful additions to a grass lawn.

Ironweed at garden edge_Eleanor_CC BY-NC 2.0
Ironweed at garden edge

You decide!
No one can—or should—tell you which plants are weeds and which are not. Of the uninvited guest plants in your yard, you decide: stay or go? Plants such as the early spring weeds can stay but not be allowed go to seed. Some may get to grow at the edge of the lawn. Some may be treasured native plants.

Options, decisions, and responsibilities abound. Just remember to use your pollinator lens from time to time when you head out to the garden to weed. Remember what A. A. Milne, the creator of Winnie the Pooh, says: “Weeds are flowers, too, once you get to know them.”

Article written by Diane Almond, Extension Master GardenerSM Volunteer.           

For more information
Gardening for Pollinator Super Heroes!
by NC Cooperative Extension

Orlando, Richard. Weeds in the Urban Landscape: Where They Come From, Why They’re Here, and How to Live with Them. Berkeley: North Atlantic Books, 2018.
(Although the plant list is specific to California, the history, discussion on IPM, and notes on many plants are appropriate for WNC.)

The Garden Detective: Caterpillar or Worm—Is It Good or Bad?

Q:  “Should I squish the caterpillars that are eating my mock orange shrub, or will they become butterflies that I want in my garden,” asked the HelpLine caller.

Sawfly larvae on rose leaves_Chris Cowan_CC BY-NC-ND 2.0_Flickr
Sawfly larvae on rose leaves

A:  After getting a description and searching lots of references, I told the caller she had sawfly larvae! And, no, she probably didn’t want to raise a new generation of sawflies. 

What is a caterpillar? What is a worm?
Typically, we think of caterpillars as larvae of butterflies, moths, and skippers (Lepidoptera), and worms as segmented legless critters that live in the ground (Annelida), but it’s complicated! Both terms are applied to many creatures that aren’t members of these particular parts of the animal kingdom. We call various other insect larvae—including sawflies (Hymenoptera)—caterpillars. We also include “worm” in the common names of lots of garden insects that are not worms, but actually in the order Lepidoptera, too: armyworms, bagworms, cabbageworms, cutworms, hornworms, inchworms, and webworms. Wireworms are click-beetle larvae (from the order Coleoptera).

Good or bad?
All of these critters are going to eat things in your garden, and many are considered garden pests. Identifying them is critical to knowing what they will eat and if you want to let them be—or not! Even the larvae of the butterflies that we encourage as pollinators eat their host plants. We want earthworms in our compost, but some worms are destructive! So, good or bad?

 Caterpillar ID
It’s mostly about the “legs.” Butterfly and moth larvae have 3 pairs of legs and 2 to 5 pairs of prolegs (leg-like parts). You know they aren’t wood-boring larvae if the prolegs are armed with hooks (crochets). Sawfly larvae have at least 6 pairs of prolegs, and no crochets.

You may need to provide host plants to feed the butterflies and moths you want. You might not typically grow what desirable caterpillars eat—or you might not grow enough to share!

  • Monarch butterfly larvae (Danaus plexippus) eat milkweeds (Asclepias). Butterfly weed (Asclepias tuberosa) is one attractive milkweed that will fit easily into most landscapes.
  • Swallowtail butterfly larvae eat a variety of plants, depending on the species.
  • Black swallowtails (Papilio polyxenes) feed on many garden crops, such as parsley and dill, while others feed on tree, shrub, or vine leaves.
  • Zebra swallowtails (Eurytides marcellus) feed on pawpaw trees (Asimina triloba).
  • Eastern tiger swallowtails (Papilio glaucus) can eat the leaves of many trees, including tulip poplars (Liriodendron tulipifera) and willows (Salix).
  • Spicebush swallowtails (Papilio troilus) need spicebush (Lindera benzoin) and/or sassafras (Sassafras albidum).
  • Pipevine swallowtails (Battus philenor) feed on pipevines (Aristolochia).

Not all moth and butterfly larvae are our friends. Many are major vegetable garden pests:

  • White cabbage moths (Mamestra brassicae) produce cabbageworms that eat all members of the Brassica family: broccoli, Brussels sprouts, cabbage, cauliflower, and many greens, such as bok choy, collards, kale, mustard, and the tops of turnips and rutabagas.
  • Hawk/hummingbird/sphinx moths (Manduca) produce tomato and other hornworms, that eat tomatoes, tobacco, and their relatives.
  • Sesid moths (Melittia cucurbitae) produce squash borers that can destroy your summer and winter squash crops, as well as pumpkins and some gourds.

Worm ID

  • Most of the soil-dwelling worms gardeners see are light-colored European earthworms belonging to the genus Aporrectodea. Earthworms are great at decomposing plant wastes. Their own wastes and their tunneling add nutrients and help aerate and drain soils.
  • Burrowing worms. “Nightcrawlers” (Lumbricus terrestris) are also European imports that burrow deeply, but clear areas near their burrow entrances at night, often creating noticeable mounds of food material.
  • Litter-dwelling worms. These include the “red-wigglers” (Eisenia foetida) used by vermicomposters. Red wigglers are not “cold hardy” in our climate, but the litter-dwelling Asian jumping worms (Amynthas agrestis) can survive outdoors and are seriously damaging forest habitats—including Great Smoky Mountains National Park!
  • Worm-like garden dwellers. Not all critters living in the soil are worms. Grubs (immature Japanese, June, and other beetles) and root maggots (fly larvae) are “bad” soil-dwelling pests that you may encounter in your garden. Grubs are usually white/gray, fat, C-shaped larvae, often found under turf. Various root maggots (Delia) attack the roots of Brassica crops, corn, and onions. Similarly, carrot rust fly larvae (Psila rosea) devour carrot roots, and sometimes celery, celeriac, coriander, dill, fennel, and parsley roots, too!

Control issues
A final note—if you choose to use pesticides to manage garden damage—be careful about using Bt (Bacillus thuringiensis) for controlling caterpillars! It will indiscriminately kill all your caterpillars, not just the undesirable ones.

Article written by Debbie Green, Extension Master GardenerSM Volunteer.

More information
Field Guide to the Southern Piedmont
by Jonathan J. Storm, Briget C. Doyle, Rachel V. Furman, Julie M. Smoak, & Melissa A. Storm
Field guide from South Carolina that includes many insects and plants we have in Western North Carolina. Good photographs and descriptions.

Jumping Worm Field Guide
from the Wisconsin Dept. of Natural Resources
Compares the European nightcrawler with the jumping worm.

Garden Insects of North America (2nd Edition)
by Cranshaw, W. and D. Shetlar (2018). Princeton, NJ: Princeton Press.

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Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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