Pest camouflaged as bird droppings attacks dogwood

Something is eating the leaves on my red twig dogwood. On some leaves, nothing is left but the center rib. I suspect it is a caterpillar that birds like to eat, because I saw a lot of bird droppings.

Those bird dropping are the caterpillars. What you see are dogwood sawfly larvae, and technically they aren't caterpillars, which are only the larvae of butterflies and moths. They winter as larvae that are yellowish, but during the summer they molt a few times and develop a white powdery covering that mimics bird droppings so predators won't eat them. Eventually, they molt to a spotty skin that camouflages well in leaf litter, where they drop down there and pupate into adult sawflies. So knock those "bird droppings" into a bucket of soapy water. There is only one generation of dogwood sawfly each year, and usually they have minimal if any impact.

My tomatoes have blossom-end rot even though I applied lime and I know the pH is correct. How can they be suffering from a calcium deficiency?

The calcium may be available, but if the plants can't transport the calcium up to the fruits in sufficient amounts, then the tomatoes still get blossom-end rot. In the kind of hot, dry weather we've been experiencing, this usually means that the plants didn't get enough water and/or a steady enough supply. Especially if you have huge tomato plants and/or they are in full sun all day, they'll likely require special attention to watering. A mature, in-ground, fruit-producing tomato plant needs deep, regular watering — one to two gallons, twice a week — when rainfall is not sufficient. A big tomato plant in a pot or raised bed will require even more. One of the biggest benefits of mulch is that it helps slow down evaporation and evens out moisture levels.

When I was playing golf, my ball went into a sand trap which was alive with little bees swarming just above the surface of the sand. I had to take a penalty stroke! Are the bees in my backyard going to get like that?

Those are mining bees, which are very docile. The males can't sting at all. They are solitary bees — they each make their own burrow in the soil — but in an ideal environment, their numbers can build up. These are short-lived beneficial bees, so in the backyard we recommend leaving them undisturbed if they're not in an inconvenient place. Read the publication on mining bees on our website or request it by calling us. And next time you play golf, play your ball without fear.

University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to the website at

Plant of the week

Dwarf Papyrus

Cyperus haspens

You don't need a large pond to grow and enjoy aquatic plants such as dwarf papyrus. This tropical foliage plant makes a nice deck and patio accent in a large container or tub with other pond plants like dwarf hardy water lily, lotus and iris. Papyrus adds a whimsical touch with its umbrella-like tassels at the end of long stems. The tassels are lime-green and turn a striking bronze later in the summer. A marginal pond plant, in its natural setting it grows at the water's edge, preferring a water depth of one to four inches over the crown. It will reach two feet tall and provide vertical interest in full sun to partial shade. Dwarf papyrus is not hardy but can be overwintered in a frost-free greenhouse or indoors when it receives the proper light and growing conditions.— Marian Hengemihle

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