Tropical Gardening Helpline: Mealy bug destroyer one predator you want around

  • Both the adult beetle and the larval form of the mealy bug destroyer eat lots of mealy bugs. (Photo courtesy / ipm/ucanr.edu)
  • The Hawaiian lady bug is a small black beetle that is a voracious eater of insect pests on plants. (Photo courtesy /whatsthatbug.com)
  • The orange lady bug also serves to control insect pests, like aphids, in Hawaii. (Photo courtesy / ucanr.edu)
  • The mealy bug destroyer eats aphids and scale as well as mealy bugs. (Photo courtesy / bugguide.net)
  • Mealy bugs gather where they can get access to plant juices, often along the stem at leaf crotches or on the underside of leaves. (Photo courtesy / onlinpestcontrol.com)

Dorothy asks: I was spraying a mealy bug infestation on my gardenia and saw this large white furry insect on the underside of some of the leaves that looked kind of like a giant mealy bug. I sprayed it also but wondered what it was. Do you know?

Tropical Gardener answer: It sounds like you encountered the larval form of the mealy bug destroyer, Cryptolaemus montrouzieri. This insect eats aphids as well as mealy bugs in both its adult and larval forms.

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The larval form of the mealy bug destroyer is small, about 3 mm or one-tenth of an inch long. Despite its size this insect can consume lots of aphids and mealy bugs. Mealy bugs are even smaller than the destroyer larvae but in large numbers and without a predator they can cause lots of damage to your plants.

Mealy bugs are essentially unarmored scale insects that feed on plant juices by attaching themselves to leaf veins or other areas on the plant where juices are flowing. They are in the Pseudococcidae family. The different species in this family have different host plants. The most common one here is Pseudococcus viburni which has numerous hosts, mostly outdoor plants.

If you were applying an organic mix of soap and oil (maybe Safer Soap and neem oil) or a systemic chemical pesticide, you would kill the mealybugs as well as the destroyer. If you have mealy bug infestations in the future that are not large, the destroyer may be able to keep them under control.

In many cases, it is a good idea to research the predators of various insect pests before you spray. Often they can do the work for you, saving you time as well as money spent on products.

The mealy bug destroyer is a good example of a predator worth encouraging. The adult form looks a lot like our lady bug. She is similar in size to other lady bugs. She has black wings and a brown head.

The Hawaiian lady bug is another insect predator. She is small with iridescent black wings. Occasionally, you may also see the species that has orange wings with black spots. These beetles as well as the mealy bug destroyer can consume a variety of insect pests and should not be killed when encountered. If you want to try to attract the mealy bug destroyer and lady beetles to your garden, you might want to check out the list of plants that attract these insect predators at the website: http://balconygardenweb.com/26-plants-that-attract-ladybugs.

Inspecting your plants regularly for insects or diseases can help keep them healthy. Early detection and positive identification of pests is a good step toward controlling problems before they cause damage in your garden.

Email plant questions to konamg@ctahr.hawaii.edu for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.

Gardening Events

Wednesday: “Orchid Diversity” starts with potluck at 6:30 p.m. at Daifukuji Soto Mission Hall on Highway 11 at mile marker 114, just north of Kainaliu. Thomas Mirenda, chair of the American Orchid Society Conservation Committee will be the speaker. For information, visit www.facebook.com/orchidsinparadise or call 328-8375.

Thursday: “Proper Pesticide Use and Safety” from 9-11 a.m. at the UH Cooperative Extension Conference Room, 79-7381 Mamalahoa Highway (across from the Aloha Theatre) in Kainaliu. The class will include WPS provisions and requirements, new rule changes and federal Worker Protection Standards (WPS) with Cal Westergard of the HDOA. A pesticide safety video will also be included. Bring your Restricted Use Pesticide license to the workshop. For more information contact Ken Love at ken@mycoffee.net or 323-2417.

Friday: “Early Bird Registration for the LICH Green Industry Conference and Trade Show” extended to Friday, Sept. 15. For more information about the conference go to https://www.hawaiiscape.com/conference/.

Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.

Farmer Direct Markets

Wednesday: “Hooulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort and Spa at Keauhou Bay

Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center

“Kamuela Farmer’s Market” from 7 a.m. to noon at Pukalani Stables

“Waimea Town Market” from 7:30 a.m. to noon at the Parker School in central Waimea

“Waimea Homestead Farmers Market” from 7 a.m. to noon at the Waimea Middle and Elementary School Playground

Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook

“Hamakua Harvest” 9 a.m. to 2 p.m. at Highway 19 and Mamane Street in Honokaa

Plant Advice Lines

Anytime: konamg@ctahr.hawaii.edu

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Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4893

Mondays and Fridays: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu