The truth about bugs: It's all about perspective

Sunday, August 11, 2013

As published in The Miami Herald

In the world of bugs, it is sometimes difficult to distinguish the good guys from the bad guys.

Not all insects are horrible. In fact, most have some redeeming qualities (except maybe bed bugs). While a bee sting hurts, bees are the world’s best pollinators. And even though roaches are extremely creepy in the house, they are fabulous decomposers. It all depends on perspective. And a plant’s perspective is a very important one. These bugs can be the reason for a plant’s survival or the cause of its demise.

For palm trees, there are a lot of insects with different roles. When considering the palm world, which bugs are bad? Which are good? Which don’t matter? And as caretakers of these majestic giants, how should we manage all of them?

Lady bugs are voracious predators of palm aphids, a palm pest that sucks nutrients out of the palm leaves.

The good guys: pollinators and predators. Palms are mostly pollinated by flies, sometimes wasps and occasionally bees. All of these pollinators are necessary for palm reproduction. To keep these pollinators around, make sure there is enough food for them. Have sufficient palms producing flowers to keep them satisfied year round. If this cannot be accomplished, you may have to cultivate supplemental plants. Since palms are not great at producing nectar, other flowering landscape plants may need to be added regardless of palm flowering schedules.

Other beneficial insects are predatory bugs. They eat other bugs, often bugs that are detrimental to palm health. A popular beneficial insect is the lady bug. Lady bugs’ favorite delicacies are palm aphids. It’s very common to see a horrible aphid infestation followed by a booming lady bug population. Next time you spot an aphid infestation in your yard, go see if the lady bugs have found this delicious treat.

Lady bug larvae are voracious predators as well. They have huge appetites in order to metamorphose into our beloved lady bug. Lady bug larvae generally look a lot like scale so it can be hard to tell them apart. If confused, remember that scale is not usually on palms, so if it’s on a palm, it’s most likely lady bug larvae.

The bad guys: weevils and scale. Palm weevils are generally introduced when transplanting a palm from the nursery. They quickly burrow into the crown of your palm, feast upon the heart of your palm and enjoy the rot that takes place afterward. Tell-tale signs of palm weevil are abnormal leaf senescence and crown rot.

Early detection is very difficult and late detection is fatal. If detected too late, removal of the palm is the only option and insecticide, unfortunately, will have to be sprayed on the remaining palms. It is important to remember that any insecticide used for “bad” bugs also harms “good” bugs, so be mindful of what you spray on your palms.

At first glance, roaches may look like weevils. They live in similar places but roaches are harmless to a palm and do not need to be sprayed or managed. Weevils can be distinguished by a very large snout-like projection from their head, called a rostrum.

Whiteflies often get a bad reputation because their honeydew covers lower plants in sooty mold. The sooty mold is harmless and whiteflies pose no threat to palm health.

While palm aphids act like all other aphids, palm aphids don’t look like aphids (or bugs) at all. They have a shield of armor that covers their entire body. At first glance they just look like little circles on the palm leaf. But underneath their shield, palm aphids pierce into palm leaves and suck out the phloem, which contains nutrients. Basically, these aphids are stealing the palm’s energy. The honeydew produced results in sooty mold that limits photosynthesis. Obviously, high populations of palm aphids can result in stunted growth.

Often, ants cultivate aphids in order to dine on the sweet honeydew that is produced by aphids. While the ants do not directly harm palms, indirectly they can be harmful since their goal is to increase the aphid population. The best way to deal with palm aphids is to simply wash them away with dish soap. The soap kills the insect and washes off the sooty mold. By using dish soap instead of oils or chemicals, you are dealing with both the infestation and the sooty mold in one step. Not only is it eco-friendly, it is efficient!

The bugs with a bad reputation: Leaf hoppers and whitefly have gained a horrible reputation simply because they produce a lot of sooty mold. Like aphids, they produce honeydew that drips down onto lower plants and can harm photosynthesis. Unlike aphids, leaf hoppers and whitefly do not harm palms. They are only using palms as shelter from the rain and sun. If whitefly and leaf hoppers are on your palm, simply spray them with a high-pressure water hose. This will definitely disturb them and cause them to fly somewhere else. (Probably your neighbor’s yard, but their dog barks all night so you are even now.) From a landscaper’s perspective, leafhoppers and whitefly need to be eradicated, but for a palm they are trivial.

Some palms are more susceptible to certain bugs. Knowing which palms are more vulnerable to which bugs helps greatly with management and maintenance. Phoenix date palms are prone to palm weevils. European fan palms often have palm aphids. Leaf hoppers love the underside of Sabals.

A lot of bug problems on palms can be avoided by proper planting. If palms are planted in the right place and given the right fertilizer, they are less likely to fall victim to “bad” bugs. It’s imperative to note that bugs on palms are inevitable, but they are rarely fatal.

When thinking about bugs, it’s important to remember perspective. A bug that may be irritating to us may be essential for your palm. Not all bugs on palms are detrimental, some are beneficial and some are harmless to palms and simply have bad reputations.