While looking at plants in the garden and landscape, they seem to be growing well, but wait, what is this? Is it a pest or beneficial? Ladybugs and praying mantids are two common beneficial insects.
Ladybugs, also called lady beetles, are a beneficial group of insects. Dr. Ric Bessin, University of Kentucky extension specialist for entomology, describes ladybugs and the common ones found in Kentucky.
One ladybug may eat as many as 5,000 aphids, which are soft-bodied insect pests that feed on plants.
The adult ladybug has a hemispherical to oval body shape. The body can be yellow, pink, orange, or red usually with distinct spots. This type of bright coloration is a warning to discourage other animals from eating them.
When disturbed, the ladybug produces an odorous, noxious fluid that seeps out of its joints. The predator is reminded by these bright markings to avoid it in the future.
Adult female ladybugs lay clusters of small yellow eggs on plants close to aphid, scale, or mealybug colonies. The alligator-like larvae that emerge feed on insect pests too. They are spiny and black with bright spots.
Even though they look like pests themselves, they are not dangerous to humans.
The larva pupates on the leaf after feeding on insect prey for several weeks. The adults move away when pests become scarce but the larvae remain to search for more pests.
During the summer, all life cycle stages can be found at the same time. Some species have several generations each year, and others only have one. During the winter, adults of some species spend the winter in a large cluster under leaf litter, rocks, or other debris.
Several ladybug species are commonly found in Kentucky in home gardens, landscapes, and agricultural fields. One of those is the pink spotted ladybug, Coleomegilla maculate.
It has a medium-sized, oblong, pink to red body with black spots. They eat mites, insect eggs, and small larvae. This one is unique because 50% of its diet is made up of plant pollen.
The Asian lady beetle, Harmonia axyridis, is large, orange, and may or may not have spots on its back. There is a black “M” over a white background on the head segment.
Even though it is beneficial, it becomes a nuisance when they find their way into homes to overwinter. If squashed they leave a stain which ruins rugs, furniture, and paint. Once inside the home, remove them with a vacuum cleaner.
The convergent lady beetle, Hippodamia convergens, is considered medium in size. It is orange and black and often sold as a biological control for aphids.
The seven spotted lady beetle or “C-7,” Coccinella septempunctata, has seven black spots on an orange background. It is medium-sized. It was introduced from Europe to help with managing aphid pests.
To maximize their impact in the important role of managing some insect pests, learn to recognize the different life stages of the ladybug. Only apply insecticides when necessary, use selective ones if possible, and use limited treatments.
Another beneficial insect are praying mantids. They are very efficient and deadly predators that capture and eat a wide variety of insects.
They have a “neck” that allows their head to rotate 180 degrees while waiting for a meal to wander by. Camouflage coloration allows mantids to blend in with the background.
The two front legs of mantids are highly specialized. When hunting, mantids assume a “praying” position, folding the legs under their head. They use the front legs to strike out and capture prey.
Long, sharp spines on the upper insides of these legs allow them to hold on to their prey firmly while eating. The spines fit into a groove on the lower parts of the leg when not in use.
There are three species of mantids in Kentucky: European mantid (Mantis religiosa), Carolina mantid (Stagmomantis carolina), and Chinese mantid (Tenodera aridifolia sinensis).
The smaller, dusty-brown Carolina mantid is only about 2 inches long when fully grown. This mantid is a native insect. The pale green European mantid is about 3 inches in length. The large, 3- to 5-inch long, Chinese mantid is green and light brown.
The female mantid lays groups of 12-400 eggs in a frothy liquid that turns to a hard protective shell where they survive the winter. Small mantids emerge in spring.
Often, the first meal is a sibling because they are cannibalistic by nature. This process naturally limits the number of mantids in the area. It takes a summer or growing season for mantids to mature to adulthood.
This is when the wings are fully developed. Mantids here have only one generation of offspring per year.
Young mantids will eat many different types of insects that are about their own size or smaller, including their siblings when food is scarce.
Fruit flies, pinhead crickets, and other small insects are excellent food for young mantid nymphs. As they grow to adulthood, they eat larger prey.
For more information about ladybugs and praying mantids, call the Daviess County Cooperative Extension Service Office at 270-685-8480, or email firstname.lastname@example.org.
Annette’s TipGreat photos and more information about insects in Kentucky can be found at the University of Kentucky Entomology department at http://entomology.ca.uky.edu/extension-entomology and at https://www.facebook.com/Kentucky-Bugs-262237810453730/.
“What’s Happening to My Vegetable Garden: Part 2” will be presented virtually by the Daviess County Public Library on Tuesday, June 8, at 2 p.m. Go to the library’s Facebook page to tune in.
Annette Meyer Heisdorffer, PhD, is the horticulture extension agent with the Daviess County Extension Office. She can be reached by calling 270-685-8480.