For those of you who tuned into the July 29 edition of Gardening in the Panhandle LIVE, beneficial insects was the topic of the day. Here are links to the publications our panelists talked about.
Mantid. Photo credit: David Cappaert, Bugwood.org.
Can an individual gardener sustain an ecosystem for beneficial insects? Penn State Article on beneficial insects that mentions some flowering plants that help support predators and parasitoids: https://extension.psu.edu/attracting-beneficial-insects
How to control leaf footed bugs? Handpick them, attract beneficials, create diverse plantings in landscape, accept some damage, and control them when in the juvenile stage.
How to stop Eastern Black Swallowtail Butterflies laying eggs on parsley – the hatched caterpillars eat it all. Plant extra or put a screen over plant.
Crape myrtles are all around good tree selections for the landscape. When left in their more natural form with just a little selective pruning, crape myrtles can provide shade during our hot summer days. Learn the many qualities of the crape myrtle with UF IFAS Extension Escambia County.
I know this is going to come as a shock to some readers, but not all bugs are bad. In fact, while there are over 1 million species of insects worldwide, less than 1% are problem pests! This problem 1%, composed of common garden pests, including aphids, stinkbugs, nuisance caterpillars, and scales, get all the attention and for good reason; they can be extremely destructive to home and commercial crops. However, the good guys, beneficial predatory insects, are out there too, providing valuable pest control day and night and should be considered in part of a quality garden pest management strategy.
Beneficials come in many shapes and sizes. Some are commonly known predators, such as spiders, Lady Beetles and Praying Mantids, while others are lesser known pest nemeses, like Paper Wasps, Pirate Bugs, and Lacewings. Regardless, gardeners should do their homework and be able to identify beneficials when they see them and allow them to do their jobs. The presence, or not, of a handful of Lady Beetles or Lacewings on the attack can be the difference between needing to treat with insecticides for an aphid outbreak or just letting nature take its course. Studies have shown that just one individual Lady Beetle in the larval stage can consume as many as 500 aphids; adult Lady Beetles are even hungrier aphid eaters! Paper Wasps, you know the ones who make the large “papery” nests around eaves of house and other structures, play an important beneficial role, frequently preying on caterpillars. If their nests aren’t near highly trafficked areas around your home and you don’t have family members allergic to wasp stings, your garden will thank you for leaving a few paper wasp colonies as caterpillar insurance!
Lacewing eggs on a Jade plant in close proximity to the author’s vegetable garden.
In many instances, beneficial insects can keep pest insect infestations at bay, allowing gardeners to spot treat outbreaks when they get out of hand or even prevent the problem from needing chemical intervention altogether.
As helpful as they are, beneficial insects in the garden won’t totally negate the need for chemical treatment entirely. From time to time, garden pest populations outpace the beneficials’ abilities to kill them and intervention from humans is needed. In these times, it is advisable to use a couple of best practices to limit exposure to beneficial insects. First, try to use selective insecticides that only target specific pests and are nontoxic to other bugs, like the product Bt for caterpillar pests (sold under many brands like Dipel, Garden Safe Bt Worm and Caterpillar Killer, Thuricide, etc). However, if a nonselective, general insecticide, like the Pyrethroids (many common homeowner insecticide brands) and carbamates (Sevin and others), is needed, timing these broad spectrum sprays for early in the morning and late in the evening when many beneficials are not very active can help reduce friendly fire casualties. Care should also be taken to only spot treat infested plants and not the entire garden, this helps reduce beneficial exposure to these broadly toxic pesticides.
Every gardener should have a plan for pest control and beneficials can play an important role in this overall strategy. Gardeners can help ensure that nature pulls its weight in controlling problem pests by taking a little time to scout for beneficial insect populations, keeping a close eye on developing pest outbreaks, using selective insecticides when you can, and only spraying broad spectrum products as spot treatments when necessary and timing those applications for very early or late in the day. If you have a question about whether or not a garden insect is a good guy or a pest or want more information on garden pest control strategies, contact your local UF/IFAS County Extension Office! Happy Gardening!
The following resources were used in the development of this article:
Do you notice a large number of bees or wasps visiting your magnolia tree? Do you see “bumps on the twigs”? Are the leaves and branches turning black? It is probably Magnolia or Tuliptree scale.
Photo by: Rebecca Bolestra
These scale belongs to a group of insects referred to as soft scales. Scale insects feed by inserting their piercing-sucking mouthpart into the plant’s vascular system and removing sugar and water from the tissue. As the insects feed the fluids become concentrated in the gut of the scale, forcing them to excrete a clear, sticky liquid called honeydew. The honeydew drips onto the leaves, stems and anything else below. Honeydew serves as a growth media for sooty mold, the thin layer of black fungus that forms on the surface. The honeydew is a food source for other insects, like bees and wasps. But, the sooty mold prevents sunlight from reaching the leaf surface, preventing photosynthesis from occurring.
Scales are identified by their body covering. Magnolia scale (Neolecanium cornuparum) is one of the largest soft scale, measuring up to ½ inch in diameter. They range from pink-orange to dark brown in color and are often covered with a white wax at maturity. Tuliptree scale (Toumeyella liriodendri) is a similar appearing scale that can infest magnolia species. But, it does not form the white wax.
Magnolia and Tuliptree scale reaches maturity in August with one generation per year. The female lays her eggs, which hatch internally and form crawlers that move from under the body covering and migrate to the underside of small twigs, where they will spend the winter. Once settled in, the young scales begin to feed and never move again, growing larger in the same spot.
Now is the time to take action. For small trees, the scales can be removed by hand with a soft brush. Horticultural oil will smother adults and crawlers, if the trees to be treated are larger or time is limited. Systemic insecticides can be applied for lasting effects. Imidacloprid is a pesticide that can be applied as a soil-drench, reducing the potential for harm to pollinating insects. In the fall, insecticidal soap can be applied to control the crawlers that hatched. Plan on treating the tree again next year. Scale population suppression usually requires at least two years of pest management. For more information on scale insect management go to: https://edis.ifas.ufl.edu/pdffiles/MG/MG00500.pdf
Wheel bugs have large beaks and a distinctive semicircular crest on their backs resembling a cogwheel. Photo by Gerald J. Lenhard, Louisiana State University, Bugwood.org.
As a gardener, the summer is the season you might feel it takes knightly status to grow fruits and vegetables. You put on your metaphorical armor, hold up your shield, and draw your sword to battle the stink bugs, squash vine borers, armyworms, green peach aphids, and more.
In these instances, it may feel like nothing in nature is on your side. But alas, there are a few insects out there that carry their own defenses. One of them is the ferocious assassin bug. These insects are predacious, loaded with powerful curved beaks called proboscises that pierce their unsuspecting prey. Once pierced, the assassin bug injects a toxin that liquefies the muscles and tissues of the prey. It then sucks out the liquefied tissue, killing its host.
Although milkweed assassin bugs vary in appearance worldwide, those found in the United States are distinctly orange and black. Photo by Gerald J. Lenhard, Louisiana State University, Bugwood.org.
Assassin bugs feed on a wide range of insects, including many types of caterpillars, stinkbugs, aphids, flies, beetles, and even mosquitoes.
While assassin bugs are our garden allies, be mindful, as their injection does pack quite the punch! Fortunately, although a “bite” from an assassin bug is painful, they do not generally require medical attention. But do seek medical attention if it causes any type of allergic reaction such as swelling, itching, hives, or difficulty breathing.
There are nearly 3,000 known assassin bug species, including many in Florida. Common species you may come across in your Florida garden are the wheel bug (Arilus cristatus) and the milkweed assassin bug (Zelus longipes). Give them their space but know that they are on your side.
