Vedalia beetles are a breed of Australian ladybug that devours their weight in cottony cushion scale pests found on citrus, olives, roses, magnolia, and acacia. The vedalia beetle claim to fame is that it was California’s first attempt at biological pest control
Back in the late 1800s, cottony cushion scale was decimating California’s citrus trees. In 1888, vedalia beetles (Rodolia cardinalis) were imported from Australia to counteract that pest, and it saved the California citrus industry
Vedalia beetle description
Like other lady beetles, vedalia beetles are easy to recognize because of their domed body shape and stubby antennae. The difference being coloration. While bright red lady bugs feature dark spots, vedalia beetles feature a much darker red dome with splotchy black markings. Adults are approximately 1/16 to 1/8 of an inch long and covered with fine hairs that can make them look more grayish than red and black. Larvae are elongate, grayish, and can look like tiny alligators.
Vedalia beetle diet
While the bright red variety most of us think of as ladybugs feeds heavily on aphids, vedalia beetles prefer cottony cushion scale insects. Adult vedalia beetles simply chew up their prey, while younger larvae pierce their victims and suck out their juices.
Vedalia beetles start out as tiny red eggs. These eggs hatch out into tiny red larva. Vedalia larva start feeding right away and they go through several instars, or developmental stages, as they grow. They continue to feed until just before pupating. Then they attach themselves to a leaf as they prepare for their final transformation. [Unlike other insects that pupate, if you touch a healthy vedalia pupa, it should move.] One week later, an adult vedalia beetle emerges, ready to lay 100 to 200 eggs in its 1 to 3 month lifespan.
Combined with a parasitic wasp (Cryptochaetum iceryae), cottony cushion scale is now well under control in California, without the use of any chemicals. Since vedalia beetles are extremely sensitive to pesticides, it is a good idea to inspect an area for these beneficial insects before spraying chemicals.
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