biocontrol

Managing Slugs in Crop Fields and Gardens

April 25, 2022May 11, 2022Maryland Grows1 Comment

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Slugs are a common field crop and horticultural pest. Managing them is challenging because their damage is often confused with other pest damage, and pesticide options are few and expensive. Luckily, knowing what to look for and the growing practices that reduce slug damage helps reduce the problems with this pest.

What exactly are slugs?

Unlike most other plant-feeding pests found in fields or your garden, slugs are not insects. Instead, they are soft-bodied, legless mollusks that are covered in slimy mucus that they secrete and leave behind as a trail. Slugs dry out easily, so they prefer environments with lots of shade and moisture. Slugs feed on a wide variety of food sources, but when they eat plants they can cause a significant amount of damage making them the bane of many farmers and gardeners.

In our area, the most common slugs found in crop fields and gardens are:

Gray garden slugs – about 2 inches long when fully grown. Ranging from cream-colored with irregular gray spots to dark brown with dark spots.
Marsh slugs – Smaller, about 1 inch long. Tend to be dark.

Eggs of both species are small, clear, round, and gelatinous. They are usually laid in clusters under plant residues.

Images of two types of slugs: gray garden slug, marsh slug, slug eggs — A) A gray garden slug, B) two marsh slugs, and C) slug eggs under old soybean roots

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From moth to monster: Hornworms return

July 8, 2019September 16, 2022Maryland Grows6 Comments

A few weeks ago you were sitting back admiring your freshly planted garden. Neat little rows of tomato, pepper, squash, and cucumber plants accompanied by flowers and herbs were all planted in view from your back deck. As you sat there basking in the evening sun, relishing in your hard work, a little moth fluttered from flower to flower sipping nectar.

hornworm moth — *A hawkmoth, the Carolina Sphinx, is the adult form of a tobacco hornworm. Photo: Mike Raupp, University of Maryland, Department of Entomology*

With her hummingbird like flutters, a Carolina Sphinx Moth floated through your garden, unassumingly laying her eggs on your newly planted tomato and pepper plants. Within a few days, from her little green eggs emerged a tiny but very hungry green caterpillar.

hornworms — *Hornworm caterpillars. Photo: Rachel Rhodes, University of Maryland Extension*

Since that day, the ravenous little green hornworm caterpillar has spent his days munching away, perfectly hidden by the copious green foliage of your tomato plants, growing bigger and bigger. You begin to notice stems of complete defoliation. Maybe you think it’s a bunny or deer having a nighttime nibble as the little green caterpillar stays camouflaged, until the moment you notice the red-tipped horn and the very large green body of a caterpillar measuring almost 4” in length hanging on your prize winning tomato plant. Continue reading →

Are Stink Bugs Bugging You? Are Wasps the Solution?

December 13, 2017December 14, 2017Maryland Grows1 Comment

Summary: Learn how University of Maryland researchers and University of Maryland Extension (UME) Master Gardeners collaborate on research to reduce brown marmorated stink bug populations in Maryland. Project Stink-be-Gone, by Rebeccah Waterworth

As temperatures cool, many of you probably have had to share your homes with bugs. One of the most notorious of these squatters is brown marmorated stink bug (BMSB) (Fig. 1). It is also a serious pest of many economically important crops. Paula Shrewsbury and I are interested in developing sustainable pest management practices for BMSB, particularly biological control using small wasps (Fig. 2). These critters are also known as parasitoids, and they lay their own eggs inside a stink bug egg. The baby wasp (larva) inside the stink bug egg eats the developing stink bug. After about 10 days, the wasp larvae have become adults, chew their way out of the bug eggs, and fly off to look for new bug eggs to parasitize! Stink bugs do not hatch from the eggs where wasps emerged (see the video at the end of this post).