A common question for gardeners at the end of the season is if one should till the soil or use no till practices. Opinions vary regarding this question, even among Extension Agents. However old crops harbor insects, both good and bad. This phenomenon was noticed on some recently cut back tomato plants. The intention was to cut the leftover spring garden tomatoes back to encourage fall production. Instead, a host plant for mealybugs was provided.
Mealybugs on a tomato plant. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments. They are about 1/8 inch in length and usually pinkish or yellowish in color. Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental and vegetable plants. Mealybug damage produces discolored, wilted, and deformed leaves.
One very common example of an insect pest likely to claim residence in your garden’s crop residue, are squash bugs. They like to overwinter on squash, cucumber, and other cucurbit crop residue. If you choose to not till your garden and leave a portion of last seasons crop in your garden, then you should consider applying an insecticide to your spent crop at the end of the season. A product containing a pyrethrin or pyrethroid as an active ingredient would be a good broad spectrum insecticide to control any pest that may reside on plant residue. More information on pyrethrins and pyrehtroids can be found at the EPA webpage: Pyrethrins and Pyrethroids. If you choose to apply an insecticide, it is important that you follow the information on the label regarding pollinator protection. Another option is to plant a trap crop on the edge of your garden to help attract pest insects away from your desired crops. More information on trap crops can be found in the EDIS Publication: Intercropping, Pest Management and Crop Diversity.
An adult squash bug on a zucchini leaf. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
So the answer to the till or no till question is…it depends. It is really up to the gardener. Yes, the residue from crops will add nutrients and organic matter to your soil, but it could also increase pest pressure in your garden. If you don’t plan to remove crop residue and don’t plan to till, then keep an eye out for what could be hiding in your garden.
August is awful. Its heat makes one miss the relative cool of July. Its rain is so sporadic that it invokes nostalgia for the rainy afternoons of early summer. But if there is a silver lining in August for gardeners, it is the simplicity that it brings. The weaker spring crops, tomatoes, squash and the rest, are all gone now, destroyed or rendered fruitless by insects, disease, and heat. This leaves only the hardened, usually pest and disease-free survivors Okra, Pepper, Sweet Potato and Eggplant. I say usually because, this year, my eggplant bed is under attack by a new-to-me pest, the False Potato Beetle!
I’ve dealt with Colorado Potato Beetles (CPB) before. Those orangish, black-striped terrors often attack my spring potato crops and occasionally bother early tomatoes. However, I’ve never seen them in late summer on Eggplant. This raised suspicion. Also, I spotted unusual, round, whitish purple creatures munching on leaves from the same plants; these appeared to be the larval stage of the unidentified beetle. A little digging led me to identify these garden pests as the lesser known, lookalike cousin of CPB, the False Potato Beetle.
False Potato Beetle munching on an Eggplant leaf in the author’s garden.
False Potato Beetle (FPB) looks nearly identical to its cousin in the adult stage. They are similarly shaped and colored, though a close look reveals subtle differences between species. While both have yellowish-orange heads and pale-yellow backs with dark stripes, the FPB’s back is slightly lighter hued, more of a whitish, cream color. Also, the CPB’s underside and legs are a very dark orange to brown, with the False Potato Beetle having lighter colored legs and underside. If you’re saying, “These old eyes will never be able to tell the difference, County Agent. Cream and light-yellow look the same to me.”, I get it. Fortunately for those of us with poor vision, the larval stage (babies) of the two beetles looks very different and is the key to correct ID! FPB larvae are larger and have a whitish coloration. CPB larvae, in contrast, are a similar burnt orange color to the adult beetle. I promise, the difference is very distinguishable!
False Potato Beetle is considered a minor garden and agronomic pest as they typically only bother Eggplant, and they don’t usually destroy entire plants. However, if you get a FPB outbreak in your Eggplant garden, they can still be pretty destructive. These beetles feed in the same manner as caterpillar pests, chewing away entire sections of leaves and stems. Unchecked infestations can defoliate entire sections of plants. So, if you find these little beetles eating away at your eggplant garden, what can you do?
False Potato Beetle larvae. Photo courtesy of the author.
First, if you scout regularly, you’ll notice the beetles and their larvae in relatively small numbers before outbreaks become widespread. I had pretty good success this year just catching infestations early and picking off the beetles I saw and squishing them. Continue scouting and squishing for a few days and pretty soon, the population is reduced to a manageable level. However, if squishing makes you squeamish, you also have some common pesticide options at your disposal. I normally encourage clients to start their chemical pest control strategy with “softer” products like Pyganic, a pyrethrin make from an extract from the Chrysanthemum plant. Pyganic works great but is a little harder to find; you may have to order online or ask your local retailer if they can get it for you. If you are unable to find Pyganic or it doesn’t perform for you, the old standby products with carbaryl or pyrethroids (Sevin, Ortho Bug-B-Gone, and others) also work well.
False Potato Beetle can be a late summer garden pain, but with regular scouting, proper insect ID, lots of squishing, and maybe a timely pesticide application or two, you should be able to continue to harvest eggplant deep into fall! If you have FPB in your garden or have another horticultural question, give your local UF/IFAS County Extension office a call! Happy Gardening!
Oleander caterpillars, which are active on some oleanders during summer, can provide a number of gardening lessons.
Oleander caterpillar moth on lantana flower. Photo credit: James Castner, UF
The adult moth is striking in appearance. The bluish to purplish moth has white dots on its black wings. The moths resemble wasps as they fly in and around oleander shrubs.
It’s the orange caterpillars with black spots and black hairs that cause problems for some gardeners.
Caterpillars are the larval stage of butterflies and moths. In order to enjoy watching butterflies and moths feeding on the nectar of flowers, some of the caterpillars must survive to become adult butterflies and moths. This is lesson number one.
Oleander caterpillars usually only feed on oleander plants. Oleanders are native to areas of Europe and Asia. This is lesson number two.
Oleander caterpillar, Photo credit: Paul Choate, UF
Oleander caterpillars benefit by us planting their food source in Florida.
This relationship between pest and plant is referred to as the key plant, key pest concept. Some other examples include St. Augustinegrass and chinch bugs, gardenias and whiteflies, crape myrtles and crape myrtle aphids, azaleas and azalea caterpillars, camellias and tea scale, roses and black spot, pecans and pecan scab, squash and squash vine borers.
Understanding this concept can be helpful in designing a “low maintenance” landscape.
When you plant roses, you plant everything that goes with roses, including the time and money required to maintain them. This applies to St. Augustinegrass, pecan trees, squash and oleanders. This is lesson number three.
Oleander caterpillars can temporarily damage the appearance of oleanders. But they cause no long-term damage for the plant. This is lesson number four. The damage is aesthetic. Oleander caterpillars can consume great numbers of leaves. However, if the plant is otherwise healthy, new leaves will be produced and the plant will continue to grow. The damage is temporary; there will be no evidence the plant ever had a problem.
To spray or not to spray for oleander caterpillars has to do with a person’s tolerance level.
If you can’t tolerate having oleander caterpillars around and the temporary aesthetic damage they cause, consider the use of Bacillus thuringiensis. It is sold under a number of brand names and many times is referred to as Bt. This bacterium only controls caterpillars so it is friendlier for the beneficial insects. When using any pesticide, always follow the label directions and precautions.
Here are links to UF/IFAS Extension publications with more info.
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:
On a daily basis, it is not unusual for our Extension Office to get calls, emails, and walk-ins with questions about insect identification. Sometimes we even get questions about imaginary insects! The overwhelming opinion by our clientele is that the insects in question are harmful to their landscapes and gardens. This is not always the case since there are more than 100,000 species of insects found in the United States, but less than 1% are harmful.
Recently I received a call about an abundance of bugs in a client’s newly installed sod. He was concerned that the insects were taking over his yard. Luckily, he was able to submit some good quality photos so the University of Florida/IFAS Extension Service could help him identify the insects.
An adult ground beetle (Mochtherus tetraspilotus). Photo Credit: Michael C. Thomas, Florida Department of Agriculture & Consumer Services
The photos were sent to a University of Florida Entomologist for identification verification. It turns out the insects were ground beetles (family Carabidae). Adult ground beetles are slender and range between 1/4″ and 3/8″ in length. Their head and thorax are much narrower than their abdomens. Ground beetles are beneficial insects that feed on moth eggs and larvae. They are known predators of soybean loopers, cabbage loopers, and velvetbean caterpillars. It is suspected that the beetles found by the client came from the sod farm and were living in the thatch layer of the sod. They were possibly feeding on sod webworms or other moth larvae.
Accurate identification is the first step of integrated pest management (IPM). In this case, the insect found wasn’t a pest at all. If you need help identifying an insect, feel free to contact your local Extension Agent. For more information on beneficial insects, visit these publications found at edis.ifas.ufl.edu.
Pesticide labels are not exciting reading materials but they contain necessary details about the specific product. The label information helps you with many decisions to use the product correctly and protect yourself and the environment during the product use. Beth Bolles with UF IFAS Extension in Escambia County will share information about a readily available product and why you should always read through the complete pesticide label.
