Beneficial Bugs

I wanted to introduce you to some beneficial insects that have recently been spotted at the Visitor Center Rondel on the Zamia pumila, commonly known as our native coonties! We have the Cryptolaemus montrouzien (easier known as the Mealybug Destroyer or Ladybird Beetles) and the Zelus renardii (Assassin bugs). I am very excited to introduce you to these two beneficial insects because they help us reduce the need for chemical sprays in the garden and make a versatile tool in integrated pest management.

The mealybug destroyer is a beneficial predator for biological control since they are fast feeding and highly mobile. In 1891, these insects were introduced to California to control citrus mealybug from Australia by Albert Koebele. They are most effective in severe infestations where food sources are readily available, and temperatures are between 64-81 degrees Fahrenheit. The larvae are white with a waxy covering that makes them look like the mealybugs they prey on, called aggressive mimicry.

Mealybug destroyers do a complete metamorphosis, and the adults have a ladybug shape but are predominately-dark brown, orange head, and have no spots. Adults are small, only 3-4 mm long.

The larvae feed on mealybug eggs, scale, and honeydew, a sticky, sugary substance secreted by scale-like insects. The honeydew becomes colonized by sooty mold, a black substance on the leaves of a plant. The sooty mold makes infested plants look even worse.

There are over 150 species of assassin bugs found here in North America. Assassin bugs are called generalist predators and prey on anything as small as insect eggs, aphids, larvae, to something as big as leafhoppers, weevils, and caterpillars.

Assassin bugs are larger than the mealybug destroyer and can reach up to 2 inches long but, on average, are about 1/2 inch. They use their curved mouthparts to feed on their prey and come in many colors, brown, tan, red, blackish, yellow, and can often be bi-colored. The larvae are similar in appearance to the adults and have the same long body. It takes two months for larvae to become a full adult.

Adult assassins are patient hunters and are known to stalk their prey and wait for their next meal. They do, however, bite humans, and we recommend not handling them. Since assassin bugs hunt and eat many of the harmful bugs frequently found in the garden, they reduce manual or chemical pest control.

Blog was written by Ashley Kush, Bok Tower Gardens Horticulture team, and photographed by Cissie Stanko, Education and Erica Smith, Business Development.