Insects flourish in warm and wet weather, so they are often most abundant in August and September. Many are beneficial and some are endemic — may be found nowhere but Hawaii — and should be protected. Others, such as the Argentine fire and and African bees, are injurious to plants and animals, including humans.
Unfortunately, some mean guys have found their way here and are hard, even impossible, to eradicate. An example is the little or lesser fire ant that is established in Puna and may ultimately find its way to suitable areas islandwide. This one is spread most often by moving potted plants from infected areas. If in doubt, bait these almost invisible insects with peanut butter on a small stick. Garden shops also offer baits. Once they overtake your garden, you will get some nasty bites. The best way to help avoid new pests is to support Department of Agriculture inspectors who are trying to stop potentially harmful insect introductions.
Don’t bring any new plants or seeds to the islands without proper inspection and permits. I recently heard a rumor that someone shipped into Hawaii a young palm plant in soil from Florida, without permits or inspection. That could possibly bring lethal yellowing disease. This disease is common in Florida where it has killed tens of thousands of palms.
As the weather warms, insects with ravenous appetites are on the increase. Some feed on plants and others feed on plant eaters. It is important to keep a close watch, as some are sneaky rascals. The moment you turn your back, they’re apt to zip out from a nearby host plant and begin munching on the best plants in the garden. Not only do insects feed on your plants, but they devour a gardener’s pride and prestige. One way or the other, you’ve got to get ahead of these creatures’ chewing, sucking, piercing or rasping mouths.
Some of the worst foes of shrubs and trees are thrips, whiteflies, mites, aphids and scales. Young thrips are yellowish, minute, slender creatures.
Mature thrips are only about 1/40th of an inch long. The little pests feed by rasping the plant surface and sucking the sap as it oozes from the wound.
Thrips often fly to roses, crotons and other ornamentals in huge numbers from nearby plants. The common Malayan banyan is often loaded with thrips. Some nurseries carry a variety of this plant that is resistant to thrips.
Aphids are a menace to tender shoots and buds because of their rapid reproduction rate. Aphids feed by sucking sap from tender plants, causing them to become deformed. These are especially common on citrus.
Nature may take a hand in controlling aphids. If you look at an army of aphids, you may spot a friend, the syrphid fly larva, deflating the juice from aphid larvae at the rate of one per minute. Another aphid enemy, the Braconis Wasp, can deal a death blow to hundreds of the tiny pests by laying its eggs within their bodies. The lady beetle may also gobble up its share.
Red spider mites are eight-legged crawlers no more than 1/50th of an inch long. Often there is quite a build-up of these damaging spiders before you notice leaves are taking on an off-yellow color. A hand lens is needed to discover mites. Some mites are virtually colorless. Others may be tan, reddish or purple.
Mites thrive when it’s dry and populations decline with wet weather. Regular showers will reduce populations.
More than 20 species of scale insects commonly attack plants. These insects fasten themselves tightly to the leaves and stems of plants and suck juice from them, turning leaves yellow, stunting growth and killing branches or entire plants.
Among scale insects, there are two major groups: armored scales and unarmored scales. As a rule, unarmored scale insects have softer shells and are larger than the armored ones. Unarmored scales almost always produce a sticky honeydew, while armored scales usually don’t. Often, you notice ants searching for honeydew before you see the unarmored scales themselves.
Most kinds of scales cover themselves with a waxy coating making it difficult for insecticides to get to them. They are at their most vulnerable stage when recently born “crawlers” emerge from beneath the protective covering of the parent scale and move about, some of them for the only time in their lives. The crawlers travel until they find a good place to eat, then become stationary, begin to grow, and produce their protective covering.
If you’ve noticed parent scales, you can assume that crawlers will emerge when plants start vigorous growth. Many predators feed on scale, so biological controls work if we are patient.
If beneficial insects, lizards and birds are doing a fair job of control, then relax. Nature tends to balance. Skinks, geckos, anoles and Jackson’s chameleons help control insects in Hawaii. Frogs and toads help, too.
Most folks don’t realize two species of snakes can be found in Hawaii. The island blind snake is an early-20th century accidental introduction. The harmless 8-inch fellow might be mistaken for an earthworm as it moves through the soil eating insects. The other is a native or indigenous species that is actually quite poisonous. It is only found occasionally in waters around Hawaii and is not aggressive. It is usually spotted in “El Nino” weather years. To learn more, read “Reptiles and Amphibians in the Hawaiian Islands” by Sean McKeown.
In the event that the unwanted insects get out of hand, local farm and garden shops have a number of safe and effective pesticides available. Read and follow label directions.