Maryland Grows

Is This a Pollinator? Five Types of Pollinating Insects You Can Find in Maryland

Gardeners, naturalists, researchers, conservationists, politicians — everybody talks about pollinators these days. It seems that pollinators need our help and we need to help them help us. However, it is really hard to protect something that we don’t fully know. So let’s take a look at our insect pollinators, how and when to look for them, and how to tell them apart.



Bees are one of the most important groups of pollinators. Aside from the well-known non-native honeybee, bees are very diverse in terms of size, ecology, and coloration. In our area, bees range from very small (like our metallic sweat bees) to large (like our carpenter bees and bumblebees), and display different colors and even metallic shines. Bees can be recognized because they have two pairs of wings, ‘elbowed’ antennae, and usually hairy legs and bodies. Bees fly and visit flowers both during daytime and dawn, and can be seen on flowers of different colors (e.g., pink, purple, blue, white, yellow).


Bumblebee. Photo: Anahí Espíndola

sweat bee

Sweat Bee. Photo: Even Dankowicz

andrena mining bee

Mining Bee. Photo: Jenny Glenn


Butterflies have ‘conflictual’ relationships with their preferred plants: while in their caterpillar stage they feed on the leaves and stems, they pollinate flowers in their adult butterfly stage. Maryland butterflies span different sizes, colors, and shapes. You may be familiar with the impressive Monarchs, who feed on milkweed and are able to migrate hundreds of miles, our very own state insect the rare Baltimore Checkerspot, or the beautiful swallowtails. Because of their special mouth shape with a rolled ‘tongue’, butterflies prefer flowers that have long tubes. Butterflies are diurnal and are usually attracted to red, orange, yellow, purple and mauve flowers.


Eastern Tiger Swallowtail. Photo: brdmrksio

silver spotted skipper

Silver-spotted Skipper. Photo: Anahí Espíndola


Moths are relatives of butterflies, but from a pollination perspective, they differ because the majority of them are active at dusk and into the night. Like butterflies, moths have long tongues that they use to collect nectar from flowers, and thus their preferred flowers are somewhat tubular. Moths can be small or large, but the vast majority of them are attracted to flowers that bloom in the evening, produce strong and sweet scents, and are usually whitish. While some pollinating moths are fair fliers, the impressive hawkmoths can hover and are easy to recognize because they are very hairy and fly like hummingbirds. Even though most moths are nocturnal (active at night), some hawkmoths are diurnal (active during the day), such as hummingbird moths.

Hemaris Hawkmoth

Snowberry Clearwing. Photo: Thibaud Aronson


I hope that after reading this, you will appreciate these little guys as much as I do. Despite hoverflies contributing to a VERY large part of the pollination of both crops and wild plants, they are unfairly overseen, so let’s set the record straight! Hoverflies are relatively small (about half-an-inch). They are flies and thus have only one pair of wings that they carry openly as a ‘T’. Hoverflies often are confused with bees and wasps because many of them have yellow stripes on their abdomens. However, it is relatively easy to tell them apart because they have two wings (versus four in wasps and bees), they hover and make very fast movements when they fly, they usually have huge eyes, and their antennae are very short. Hoverflies are diurnal pollinators and prefer white, yellow and greenish flowers.

Virginia Flower Fly

Virginia Flower Fly. Photo: John Flannery


Margined Calligrapher. Photo: Jesse Rorabaugh


Certain families of this very large group of insects visit and pollinate flowers while feeding on pollen. Beetles that pollinate can be minute to large. One can recognize them because of the hard ‘shield’ that covers their backs and the usual hair that covers at least part of their bodies. Beetles can be active during the day and night hours and prefer flowers that are greenish, white and relatively dull. In Maryland, most of our pollinator beetles are soldier and longhorn beetles. Next time you are around flowers, I invite you to take a close look and I am sure you will have no trouble finding these guys!

Yellow-horned Lepture

Yellow-horned Lepture. Photo: John Flannery

Goldenrod Soldier Beetle

Goldenrod Soldier Beetle. Photo: Mark Nofsinger

This is definitely a pollinator but I still don’t know what it is!

Have you found an insect on your flowers, but you can’t figure out what it is? There is a great tool to identify it, and it is just one picture away! This magical tool is a phone app called iNaturalist. After taking a picture of the insect in question you can upload it to the app and submit it for identification. This app will let you know what is likely to be the species you have seen. It also will let other users like you learn from your observations and help you identify them. Also, besides letting you visually search for observations close to you, the app/website is simple to use, and the users are friendly and helpful. To learn how to use this app/website, refer to this very good tutorial on iNaturalist.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park

Dealing With Standing Water in Your Yard

standing water in the yard

Deal with standing water by adding topsoil or planting vegetation that prefers boggy areas. Photo: UME / Ask an Expert

Q: Our backyard has very low spots where the water ends up after heavy rains. How do I deal with this? I would like to plant a garden of shrubs and perennials but don’t think many can take that much water. Red maples and birch seem happy, but the hydrangeas I planted last year all died. It gets quite a bit of sun.

Most plants will not tolerate sitting in standing water or saturated, soggy soil for long periods. You may be able to add one to two inches of soil to fill in low spots or raise the grade enough so that water will run off better or at least not accumulate there. A steep grade is not necessary or desirable because in dry years you do want the water to sink into the soil and down to plant roots.

This past year we had abnormal rainfall — about twice the average. Many people lost plants in areas where they had grown for years but were now under water too much for the plants to survive. The maple you have may be red maple, which is happy even in a bog; the birch is probably a river birch. Hydrangeas love moist soil, but cannot tolerate standing water. In saturated soils, the water pushes out the oxygen roots need. Eventually, the plant drowns, unless it is a plant adapted to saturated soil, i.e. a bog.

You may have a good location for a rain garden. Many plants love this environment — some stunning natives in particular, such as button bush and clethra. (Both are also butterfly magnets!) Take a look at the Home & Garden Information Center’s webpage on stormwater and rain gardens.

Don’t get bogged down (no pun intended!) with details. Just plant what likes “wet feet.” Native plants are the best. For more plant choices, look at the U.S. Fish & Wildlife Service’s excellent publication, “Native Plants for Wildlife Habitat and Conservation Landscaping: Chesapeake Bay Watershed.” In the lists, ‘Plants for Freshwater Wetlands and Other Wet Sites’ should be helpful. (There is also the equivalent online database,

You may not have standing water continuously in the future. However, it is predicted that we can expect a lot more wet years and extreme weather ahead because of climate change. A rain garden is a smart way to handle this, as long as this spot does not hold water all summer (and breed mosquitoes). When you install a rain garden, the plant roots will be pulling in the water and drying up the low area, too.

By Ellen Nibali, Horticulturist, University of Maryland Extension Home and Garden Information Center. Ellen writes the Garden Q&A for The Baltimore Sun.

Have a plant or insect question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.

Hail damage in vegetable (and other) gardens

Did you get hail last weekend? As is usual with spotty hailstorms, some places were pummeled and some were completely spared. The hail at my house was pea-sized. After the storm, I checked out the damage to my eggplant leaves:


These plants are in pots on my deck (which helps me avoid flea beetles). Not much else in my gardens was hurt, but it got me thinking about writing about hail damage for this blog post. And then MG Pam Hosimer told me about what happened in her garden, not too many miles away. This is the hail she got – !!!

hail damage 1

Read More

Yard and Garden Tips and Tasks for June

July Flowers

Outdoor Yard and Garden Tips

  • Cut iris flower stalks down to the crown when they are finished blooming. Leave the foliage alone. If your iris are over-crowded after flowering lift and divide them. Check rhizomes for iris borer.
  • Practice IPM (Integrated Pest Management) in your landscape. Do not spray your trees and shrubs preventively. This kills the predators and parasitoids that are helping to keep destructive pests under control.
  • Water newly planted trees and shrubs until they become established (for about 2 years), especially in the summer and fall. Water deeply by allowing the water to soak into the soil directly underneath and around the root ball.  Check the depth of water penetration into the soil by digging a small hole after watering. It should be moist about 6 inches down. A 2-3 inch layer of mulch is helpful. Keep mulch away from the trunk or stem.

Indoor Plant and Insect Tips

pider mite webbing

Spider mite webbing

  • Monitor houseplants kept indoors for mealybugspider mitesaphidswhitefly, and scale. If houseplant pests are a problem consider spraying with a labeled horticultural oil or insecticidal soap. If possible, move the plants outside before spraying and when dry, move them back indoors. Discard heavily infested plants.
  • Pantry pests, like Indian meal mothsgrain beetles, cigarette beetles, and carpet beetles may be found around windows trying to get out of your home. These pests can be swept up or vacuumed.  No chemical controls are recommended.

See more June tips and tasks.

What’s Eating My Rose Leaves?

roseslug sawfly damage on rose

Rose slug sawfly damage on rose. Photo: UME/Ask an Expert

Q: My rose leaves have white spots and holes in them. What causes this and how do I treat it? Is there a natural remedy that does not involve powerful chemicals?

Answer: It looks like your rose has symptoms of sawfly damage. Check the undersides of the leaves and look for tiny green larvae that look like caterpillars. These are the juvenile stage of an insect called rose slug sawfly.

Rose slug sawflies are neither slugs nor flies. They belong to the same order of insects as wasps, bees, and ants (Hymenoptera). Adult female sawflies use their unique ovipositor (egg-laying part) to saw a small slit in a leaf or stem where they lay their eggs. When the eggs hatch, the larvae feed on the leaf surfaces and cause an etched appearance. Some rose slug larvae chew through leaves entirely. Damaged foliage turns brown and curls up as the season progresses.

bristly roseslug on rose leaf

Bristly rose slug (Cladius difformis). Photo: Whitney Cranshaw, Colorado State University,

bristly roseslug sawfly adult

Bristly rose slug (Cladius difformis), adult stage. Photo: Whitney Cranshaw, Colorado State University,

In Maryland, there are three species of rose slug sawflies that cause damage to roses: the bristly rose slug sawfly, the rose slug sawfly, and the curled rose sawfly. Most of the feeding activity on roses in Maryland is seen in May and June, but sawfly larvae can continue to be active until fall. Other insects, such as Japanese beetles, also cause chewing damage on rose foliage (typically in June-July).


Browning and leaf curling from rose slug sawfly damage. Photo: UME/ Ask an Expert

The best way to manage rose slug sawflies without chemicals is to monitor your plant(s) for damage symptoms and manually remove any larvae (squish them or toss them). Insecticidal soap, horticultural oil, and spinosad work well against these sawflies. These products are environmentally friendly insecticides listed by the Organic Materials Review Institute (OMRI). As with any pesticide, read and follow the label instructions carefully. Avoid sprays when your roses are in bloom, to protect pollinators and other beneficial insects.

Predatory insects and parasitoids help regulate sawfly populations naturally. Adding more flowering plant diversity to your landscape will provide food and habitat for beneficial insects that in turn will help reduce pest problems.

Additional Resources

Rose Slugs on Shrubs | UME Home & Garden Information Center

Rosie Defoliators | Bug of the Week, University of Maryland, Department of Entomology

Rose Insects & Related Pests | Clemson Cooperative Extension

Sawflies | University of Wisconsin-Madison

By Christa K. Carignan, Maryland Certified Professional Horticulturist, Coordinator, University of Maryland Extension Home & Garden Information Center

Have a plant or insect question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.

Featured Video – Building a cinder block square foot garden

This video from NC State Extension outlines a great square-foot garden build created with cinder blocks.  Use the holes in the blocks to plant ornamentals and other plants that will attract pollinators to your food crop.

Vegetable Garden Updates

Allium leafminer

HGIC received its first allium leafminer (Napomyza gymnostoma) question from a Baltimore gardener. The pest symptoms were discovered on chives growing in a window box. If you observe this pest please send photos and information through Ask an Expert.

The white spots are feeding punctures where adult leafminer flies  fed on plant sap. Photo credit: Lawrence Barringer, Pennsylvania Department of Agriculture,

The white spots are feeding punctures where adult leafminer flies
fed on plant sap.
Photo credit: Lawrence Barringer, Pennsylvania Department of Agriculture,

Mated female flies lay eggs on lower leaves and the hatched larvae feed on leaves, creating visible trails (mines) between leaf surfaces. They pupate in protected plant parts (bulbs. leaf sheaths) and a second generation of adults emerges in September and lays eggs. Larvae feed and overwinter in the pupal stage inside infested plants and adjacent soil.

A floating row cover can be used to exclude adults in spring and fall when they are flying and searching for host plants. Neem oil and spinosad are organic insecticides that may be effective in controlling allium leafminer. Here is some detailed information from Penn State (this European pest got its U.S. start in PA in 2015) and UME about the allium leafminer.

Tomato Planting Tips

Last year’s blog post has 5 tips for people who are ready to plant!


Spring Weather Is Tough on Seedlings and Transplants

And for those who could not wait…erratic spring weather is hard on the tender transplants of warm-season vegetable crops. Leaves that are yellowed, bleached, bruised, torn, punctured, spotted, and discolored are showing symptoms associated with challenging spring growing conditions. These include high winds, cool night temps, cloudy and rainy weather, and rapidly fluctuating air temperatures, etc. In addition, soil temps are relatively low, so root systems are slow to grow, pick up nutrients, and become established. Under such harsh conditions plants just sit and get beat up by the elements.

Tomato leaf tem that has been battling the April elements.

Tomato leaf stem that has been battling the April elements.

Pepper grows more slowly than tomato so expect plants to struggle for a while as they get established. The recent cool nights will not have much effect on later flowering and fruit set, but do pinch off pepper blossoms for 3-4 weeks to get strong root systems.

For tomato, night temperatures below 50-55 degrees F. typically cause pollination and fruit development problems (even though only buds are exposed) resulting in “catfacing” of tomato fruits (crevices, hollows and holes).

Catfacing on an un-ripe tomato

Catfacing on an un-ripe tomato

There is no way to prevent this other than holding off on transplanting until late May. Cultivars vary in the degree to which low night temps will negatively affect fruit. It’s typically best to immediately remove these fruits as they don’t develop or ripen well – only a small portion of each affected fruit may be edible.

Here’s additional information on vegetable seedling and transplant problems.

New Basil Cultivars with Resistance to Downy Mildew

Four new basil cultivars with downy mildew resistance are available for home gardeners- ‘Obsession’, ‘Devotion’, ‘Prospera’, and ‘Amazel’ (sold as plants). Seeds can be ordered from some online vegetable seed suppliers. ‘Amazel’ plants may be difficult to find at this time.

‘Prospera’ and ‘Amazel’ may be the best bets at this point, based on 2018 results from a Cornell University research trial.

Fabric Grow Bags

Many more types and sizes are coming on the market and gardeners seem to really like them. They are versatile, reusable, and affordable. Plant roots are air-pruned when they reach the breathable fabric. This promotes root branching and a larger overall root system. Here’s a 5-gallon bag (with handles) that we planted with herbs for Maryland Day on April 27th:

Photo credit: Jon Traunfeld

Photo credit: Jon Traunfeld


Summer squash growing happily in 20-gallon fabric bags.

Summer squash growing happily in 20-gallon fabric bags.


What’s in the Bag?

Be selective when buying growing media to fill containers. Products can vary greatly and carry an assortment of names- potting soil, topsoil, planting mix, etc. Look for products that are soilless (no sand, silt, or clay), are homogeneous in appearance, fairly lightweight when dry, and smell earthy.  A 1:1 mixture of compost and a soilless growing medium works well for most container gardens. Our “Soil for Containers” web page has more information.

The label on this bag lists “aged forest products and perlite” as the components.  The clods and lack of uniformity suggest it might hinder the growth of container plants. Photo credit: Jon Traunfeld

The label on this bag lists “aged forest products and perlite” as the components. The clods and lack of uniformity suggest it might hinder the growth of container plants.
Photo credit: Jon Traunfeld

By Jon Traunfeld, Extension Specialist