Myoporum Thrips

Summary: “Myoporum Thrips.” A name of a new San Francisco alternative-rock group or the winning word for the National Spelling Bee? Neither! Actually it's a bug doing lots of damage to certain plant life along the Pacific coastline, but there are new products that really help.

Myoporum thrips are bugs that recently have become nuisances in the United States. Myoporum is a type of flowering shrub that originated in Australia. Thrips are tiny bugs that suck up the juices of such plants to the point the plant dies.

Older style treatments for the thrip include foliar applications of selected pesticides such as Merit 21(imidacloprid) and Conserve (spinosad).  Spinosad is derived from beneficial microbes and has low to moderate adverse impact on natural enemies. In comparison with other insects most thrips are difficult to control effectively with insecticides because of their tiny size, hidden feeding behavior and protected egg and pupal stages. With most thrips species, eggs are protected within plant tissue and pupae are in the soil and will not be killed.

Newer products, like Safari 20 SG Insecticide, are fast-acting insecticides that are  rapidly absorbed by the tree. This results in faster control than with less systemic products and also extends the application window later in the season. When Safari is sprayed on a tree's trunk, it penetrates the bark into the xylem and is then transported upwards to where pests feed.

Myoporum thrips were first discovered in Orange County, California in 2005. Since their arrival, these thrips have spread to many different parts of California, including Santa Barbara, San Diego, Ventura, and Los Angeles. It remains a mystery as to how the bugs arrived in the United States in the first place, but some experts conjecture that they were accidentally delivered from Australia. Too bad the kangaroos couldn't eat up these pests.

Before we learn about the bug, let's learn about the plant. Myoporum is native to Australia and New Zealand. There are Myoporum ground covers and tree species that are widely planted in Southern California because of their minimal water requirements and ease of maintenance. All these factors make it a very desirable plant for the arid California climate. It has white flowers with purple berries. Some varieties of the plant also have pink flower petals. Talk about a great Mother's Day present! One other neat aspect of the Myoporum plant is that it originally there weren't too many predators that fed off of the plant. Unfortunately, this new pest has come along and ruined everything.

If you don't live in these areas, or you don't live in California, you may think you have little concern about Myoporum thrips. Well, think again. There are some disconcerting facts about the plant that may cause concern for people in the United States. Because of the three advantages the plant has, the people of California have planted Myoporum plants on the sides of thousands of miles of roads and highway. The plants look wonderful to passersby and they do not require a lot of work. And, unlike many beautiful flowers and plants, the introduction of pests initially was not a worry. However, now that Myoporum thrips feed off of these plants, the Myoporum plant has become a threat. There are so many of these plants dispersed throughout California that the thrips can easily spread to unaffected areas. And they will have plenty of food to keep them alive and reproducing.

Myoporum plants that have experienced damage by thrips are typically characterized by curled or swollen leaves. They may also produce galls. Galls are unusual growths of plant tissue caused by insect, fungi or parasites feeding off of the plants. They may also be caused by adult thrips laying their eggs in the Myoporum plant. So, if thrips damage a Myoporum shrub, the plant itself will become twisted and its leaves will curl and have galls. Depending on the number of thrips feeding off of the shrub, it may die.

Myoporum tree

Let's move on to the bug. The Myoporum thrip is very similar to the many species of thrips that exist. All thrips are absolutely tiny. They measure no more than 1/20 of an inch. They have long wings and narrow bodies, but do not fly well because they are so small. They can easily be picked up by the wind and scattered to other locations.

The adult Myoporum thrip has a black body, while its larvae are usually orange. These thrips tend to be the only ones that feed on the Myoporum plant. One of the most worrisome facts about the Myoporum thrip is that experts do not know if there are any other insects or animals that prey upon the Myoporum thrip. Populations can explode if no predators exist.