Bad Bug Guide
Written by Haley Hopkins
The good, the bad and the buggy.
While we’ve done our best to provide you with a straight-shootin’, no-nonsense bug guide, it’s worth noting that these freaky friends and foes cannot always be neatly divided into clean categories with fool-proof strategies for management. The notion of “extermination” is a foolish one; bugs have lived over 400 million years of life on this planet and have survived multiple mass extinctions. Let’s face it: they’re here to stay. And that’s a good thing!
As senior architects of our ecosystems and the first creatures to develop wings and take flight, learning more about them, in their simultaneously alien yet deeply terrestrial complexity, is an important piece in the puzzle of learning how to participate in our world as stewards of benevolence. So maybe the bugs aren’t “good” or “bad”, but instead the bugs just are. ~They contain multitudes~ And from pollinating crops to vectoring diseases, the bugs, above all, are busy.
This is where integrated pest management comes in, or “the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest population and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment” (as defined by the UN’s Food and Agriculture Organization). Finding your method for effective pest control is a bit like engaging with zodiacs and horoscopes. Every gardener seems to have their own mysterious synergy with different techniques and tools, and sometimes it’s a total crapshoot that leaves you scratching your head, not so sure about it all. For no logical reason, the “tried and true” methods that work for different people can seem totally randomized. From bamboo vinegar loyalists to Dr.Bronner’s disciples, it is a personal quest that one must endeavor on. Luckily there are tons of techniques, and combo moves are encouraged. Think of it like building your DnD character before a campaign. It’s a bug-eat-bug world, so let’s go over how our facilitation in the garden can fit into it.
Aphids are an inevitable garden pest that you’re bound to encounter, but luckily finding them is never the end of the world. They live in colonies of mixed ages and are about the size of a pinhead, with little pear-shaped bodies. The most common colors are black and green, but aphids can also be brown, yellow, even red.
Many aphids are specialists, meaning they only feed on one genus or species of plants. One example of this is Oleander aphids– those pesky yellow ones with little black legs that always pop up on milkweed. Some aphids, however, are generalists and feed more buffet style, eating a variety of plants. They’re all sap suckers though, which means that they attach their threadlike mouthparts to plants to feed. This produces a waste product called honeydew, which we’ll return to later. Aphid anatomy may be a little gross, but it’s also convenient because they can easily die during removal– blasting them with the hose will usually tear them in two, leaving their mouthpart attached to the plant and causing their body to fall off so that they die.
While physical removal by wiping with a wet towel or spraying with the hose works great, you may need to use other methods if the population gets big. Checking on your plants regularly is a big part of pest control, as it allows you to catch things before they reach levels that are harder to manage. Aphids have strength in numbers, and the more established they get, the more damage they do to plants, which causes leaves to curl and allows them to hide easier. Common remedies include insecticidal or castile soap, neem oil, Dr. Earth Final Stop Yard and Garden Insect Killer and various other horticultural oils, or natural predation by lady beetles, lacewings, predatory wasps, and hoverflies. More serious last-ditch efforts would be spinosad, pyrethrin or diatomaceous earth, none of which are recommended before trying a cocktail of the aforementioned strategies. If you’d like to go for the common route of a neem or castille spray, there are a few tips to help make your application the most successful. For neem, make sure to emulsify it with a little bit of warm water before filling up the rest of your spray bottle, otherwise you’ll be stuck with a not-so-potent elixir and a glob of neem stuck at the bottom. Castille soap doesn’t need to be emulsified, just shake it up and you’re ready to spray. For both methods make sure you get a good spray, we’re talkin’ tops and bellies of leaves fully covered, and dripping into the soil below. Spray at dusk after the hot sun has clocked out for the day to avoid setting your plants up for a sunburn, and do this once every 7-10 days. Neem oil kills on contact and won’t leave residues that hurt natural predators like bees, as they are not eating leaves.
Aphids live where they eat, so the first step in maintenance is just checking under leaves and inside of the crevices of new leaves, buds etc. An infestation will look like leaf curling and yellowing, stunted growth, and, often, an increased presence of ants in your garden. Ants and aphids have a little mob-like business agreement; the aphids do their thing, sucking on plants and producing honeydew, and the ants, who love eating honeydew, set up shop so that they can tend to the aphid colony like little farmers and protect their herd from predators. So, this brings us to an important and often overlooked method of aphid control: ant control.
Predatory insects are all-stars in the complicated world of insect relations. You can go straight to the source and buy containers of lady beetles and lacewings, but that method isn’t always fool proof since you may not have a garden they’re interested in setting up camp in yet. Courtship works better if you’re willing to play the long game, and who doesn’t want to create habitat for these critters anyways! While many natives attract these little guys, some non-native food crops like fennel and dill can also bring in predatory wasps since they feed on them. (Just be careful where you plant fennel, as it can become rather invasive in some parts of LA County) A really great native to attract insects like hoverflies is yarrow. When their populations are high they can control as much as 70-100% of an aphid population, plus they’re super cute. Keeping a layer of mulch in the garden helps to create lasting habitat for hoverflies, as they often pupate and overwinter in the leaf litter surrounding plants. In addition to this, planting species that have a long flowering season and produce pollen early is also helpful– think willows, native grasses and sedges, California poppies, etc. More on this later, though.
If you build it they will come, and if you didn’t build it, well, they’re probably already here building their own empire. Ants. Tiny yet mighty, and generally omnipresent.
In 2022, after extensive research and data integration from every continent and major biome, a team of researchers at the University of Hong Kong’s Insect Biodiversity and Biogeography Laboratory estimated that there are 20 x 10^15, aka 20 quadrillion, ants on the planet. That 20 with 15 zeros after it leaves the biomass of ants weighing in heavier than the combined biomass of wild birds and mammals, or equal to 20% of human biomass. So, there’s a lot of ants out there.
On their own, ants aren’t going to do much direct damage to plants in the garden, but keeping their populations and operations in check is essential for long term plant success, and for your own sanity. Before diving into pest management, it’s important to highlight the benefits that ants bring to our gardens since we’re bound to bump into them. They’re great at aerating soil since the tunnels they dig help carry oxygen, water and different nutrients to root systems. Surprisingly, they can also assist in pollination while marching between different flowers and plants on the hunt for food. Lastly, while they act as predators to a few other pests like flea and fly larvae, some caterpillars and termites, some ant species are important food sources for other members of the food chain like lizards, frogs and birds, who will also do some of our bidding by eating a variety of other pests. Such is the circle of life!
That being said, the ants don’t get let off the hook so easily. As mentioned earlier, ants and aphids have quite the business agreement. And in true entrepreneurial fashion, or really just plain old co-dependency, the ants have also made a very strong alliance with scale bugs. It’s a simple quid-pro-quo agreement– the ants are playing the long game with a free food source that just sits still, and the scale is too zoned out sucking on plants in zombie mode to notice that, while being protected by other predators, the ants still take sacrifices of their own fairly regularly. More on the gross little world of scale bugs later though.
What does realistic and achievable ant management look like? Most likely it will consist of a combination of different methods, all dependent on your comfortability and personal situation. Knowing what type of ants you have is very helpful when choosing a pest management strategy too. Argentine Ants, for example, not only are invasive and do harm to native ant colonies and food chains, but they also form mega colonies that consist of multiple queens and a vast, widespread nest. The sugary boric-acid baits that are nontoxic to people and pets (unless eaten in large quantities) are a great place to start. These baits work slowly– upon setting them you may see a surge of ants, but as they carry it back to their nest to feed the queen(s) and the colony, the die off will begin. For a homemade recipe, mix 1 cup sugar, 3 cups water and ~1 tsp high-purity, aka 99%, water-soluble boric acid. We use the KM AntPro Liquid Ant Bait dispensers to hold the sugar bait at our shops. Some people have also found success by mixing their sugar and boric acid with peanut butter– this works well if the ants that are pestering you are the type who are more attracted to fats/oils/proteins. A good recipe for that version is 1 big ol’ tbs of peanut butter, 1 tbs sugar and 1 tsp borax. To apply the peanut butter bait you can stuff it into 1” cut sections of straws, or place little blobs of it in bottle caps around the yard. Ant bait gel like Optigard, which contains thiamethoxam, is another good option. Here is a good brief on the various ants that live in Southern California and what they’re attracted to, and if you really want to go down the ant’s nest, here is a thorough species identification guide.
They had a brief cameo in the section above, so now let’s really focus in on the freaky little creatures otherwise known as scale insects. There are two categories of scale insects– Armored scales (Diaspididae) and Soft scales (Coccids), and within those categories there are many, many different species. They’re all fairly tiny, usually around 1/10” in length. The bugs really don’t look like bugs at all, as they hide under their shell/tent-like coverings and look more like little warts or buds attached to the stems and leaves of plants. They’re also rarely mobile, as they prefer to sit and suck juices out of the plant material than crawl around and explore. Armored scales are often easily separated from their covers, which usually develop ring-like patterns on them. Once an armored scale finds a spot it wants to feed, it will settle in and lose its legs, rendering it unable to move. Truly riskin’ it for the biscuit. Soft scales on the other hand, will generally retain their (basically invisible) legs and can move veeerrry slowly upon plants, though they will usually opt to park and camp out in one spot. What can they say, they’re ruled by the juice! Even though they’re pretty disgusting in our eyes, lots of beneficial critters view them as a lovely buffet offering. Parasitic wasps, lady beetles, various birds, etc will help to keep them in check, so half of your pest management is already outsourced!
For your management techniques, winter season application of horticultural or neem oil will help to take out many, though not all, scale species. The crawling scales become active in late winter, so this is a great time to strike, especially right after a rainy period when the weather is still cool. As winter deciduous plants wake up and buds begin to swell, so do lots of overwintering bugs who are attracted to new, succulent plant growth. That being said, many scale populations really seem to swell in the summer and fall too. To keep these species at bay it’s a good idea to keep your plants well pruned so that there is good airflow and an open canopy, which in turn will expose scale and other antagonistic insects to the heat and their natural predators. A great first step, though tedious, is physical removal– grab an old toothbrush and go to town scrubbing and detaching the scale. Most of them will die in this process. This disturbance is also helpful, as the cover of mature, armored scales protects them from oils and if you don’t get the whole bug off, you’re probably at least getting that part off. You can also spray alcohol on a paper towel and wipe/crush away the bugs. After this, you can still apply neem or horticultural oils in summer/fall seasons, you just want to be careful to not do it during extremely hot periods and after the sun has gone down for the day. Limiting heavy oil application during the summer is ideal, as overuse can be harmful to plants while in a state of energy conservation. More info on types of scale and scale management can be found on the University of California Agricultural and Natural Resources Website.
Mealybugs, though covered in a white/gray wax, often look slightly fuzzy, especially when spotted in large numbers on plants. They will hide in the nooks and crannies of leaves, especially on new growth. Weighing in around aphid size, they are also sap suckers and behave similarly to scalebugs. Think of them as scale bugs with fancier coats on. The mealybugs suck on leaves, excrete sticky honeydew, and then black sooty mold grows on top of the leaves which can cause a lot of damage if left to run rampant. Spiders, lady beetles and lacewings are just a few of the beneficial insects who like to eat mealys, so definitely work to welcome those into your yard. Ant management will also help with mealybugs since the honeydew is what links those two.
In addition to facilitating the bug wars mentioned above, pruning highly infected areas of plants is a good idea. Just make sure to take your clippings straight to the green bin and to clean your tools, as mealys don’t fly and you may be giving the little freeloaders a quick ride to a new feeding zone. Young mealybugs can often be blasted off of a plant with good old water pressure and determination, but if that doesn’t take care of it, or if the infestation has already grown, spot treating with isopropyl alcohol is a good next step. Wiping off mealybugs with 70% or less isopropyl alcohol will take care of most of them and essentially disintegrate them in the process. You will most likely just have to repeat the process a few times, especially if there is a high presence of honeydew/black sooty mold on leaves.
Surprise! More sap suckers. Except these ones, staying true to their name, do in fact fly. Whiteflies are extra tiny aphid-like bugs that aren’t actually flies, but that doesn’t matter. What matters is keeping them off of your coveted new, tender growth! A tell tale sign of whiteflies, if you haven’t already stirred the little cloud of them when you brush against your plant, is leaves that look yellowed, dry, generally distorted or discolored. They also will often bring in black sooty mold on leaves. The young nymphs are the ones who fly and do the most damage, and as they age they say “who needs legs anyway”, molt, and pull a play out of the scale book of sitting, sucking and chilling on leaves. A solid application of neem oil, castille soap (or a combo), Dr. Earth Final Stop Yard and Garden Insect Killer, or horticultural oil is very effective at treating young populations of whiteflies, and multiple applications will most likely be necessary as it can be difficult to knock all of them out in one go. As always, make sure to prune out damaged leaves while working to manage pests as that will liberate the plant of wasted energy towards areas that may as well be lost causes due to damage.
Misunderstood artists at heart, but downright troublemakers in reality: Leafminers. I think of them like little graffiti artists tagging up your building, aka your plants, except instead of just a topical paint application they work more Michelangelo style and chisel out layers of leaves with their mouths. We can’t deny that the plant tattoos they leave are cool, but snap out of it! These bugs are stinkers. Adult leafminers are generally low key– non-descript, black flies that aren’t doing too much to your plants. Their immature offspring though, little yellow colored larvae, are the ones chewing up plants. Many beneficial insects will parasitize or eat leafminer larvae to keep them in check, but if you are experiencing a lot of plant damage your two to-do’s are 1) pruning off highly damaged/infested plant areas and 2) giving the plant a solid application of neem oil.