Lady Beetle Season

June 14, 2019

Written by Mary Louise Flint

 

 
 The convergent lady beetle eats an aphid.

Late spring is a glorious time for lady beetle lovers. Why? Because aphid populations are at their peak, and aphids are the prime food for the red and black lady beetles most people are likely to recognize.


Although many people call them “ladybugs”, lady beetles is the correct term.  These wonderful insects are beetles in the insect order Coleoptera. True “bugs” such as stinkbugs belong in the Order Hemiptera, which, unlike beetles, have sucking mouthparts, soft membranous forewings and incomplete metamorphosis with no pupal stage.


There are hundreds of species of lady beetles in California. They are all members of the family Coccinellidae. Lady beetles can be readily recognized by their shiny, convex, half dome shape and short, clubbed antennae. Some people confuse the spotted cucumber beetle with lady beetles, but that plant-feeding pest can be quickly distinguished by observing its long antennae and more oblong body.

 
 A convergent lady beetle larva eating an aphid.
 

Although most people recognize lady beetle adults, the alligator-shaped larval stage baffles some observers.These immatures are often mistaken for plant pests, when, in fact, lady beetle larvae, like the adults, are voracious predators. Just a few of them can clean the aphids off your rose bush in a matter of days. The quiescent pupal stage, in which the larva transforms into an adult beetle over a period of several days, can appear even more mysterious to the uninitiated.

 
 A convergent lady beetle pupa.
 

 
 Convergent lady beetles may have anywhere from 0 to 13 spots.

The most common native lady beetle in our area is the convergent lady beetle, Hippodamia convergens.  It is distinguished by the two converging white markings on its thorax. Although it often has 13 spots, some adults may have fewer spots or no spots at all. Counting spots on these lady beetles is not a reliable way to identify them. Convergent lady beetles head up to the foothills and mountains after aphid populations crash in the summer and may spend the winter in large aggregations under several feet of snow, emerging to fly back down into the valley when aphid populations start growing the next spring.

 
 The sevenspotted lady beetle.

Another common native lady beetle in our nature area is the sevenspotted lady beetle, Coccinella septempunctata, which usually does have seven spots. It is more round than the convergent lady beetle and doesn’t overwinter in the mountains.  

 
Three different color and spotting forms of the multicolored Asian lady beetle.

Among the lady beetles now most frequently seen in the Sacramento area is the multicolored Asian lady beetle, Harmonia axyridis. Like the convergent lady beetle, individual beetles may exhibit one of several different patterns of spots on its wings and beetles vary in color from orange to red. It was introduced from Asia about 35-40 years ago to help control aphid pests in the eastern U.S. and has spread throughout the continent. It is a little larger than most native lady beetles, feeds on other soft-bodied insects in addition to aphids, and may overwinter in bathrooms or attics.

 
 Adult, larva and pupa of the multicolored Asian lady beetle.
 

In addition to these red and black lady beetles, which feed primarily on aphids, there are numerous other lady beetles that focus their feeding on scale insects, whiteflies or mealybugs. Almost all the lady beetles in California are predators of potential pest insects and are considered beneficial. If you see them along the trail or in your garden, be sure to admire them and protect them.

 

 
  Lady beetle eggs are laid on end in groups.

 
Author:  Mary Louise Flint, Docent, Effie Yeaw and Extension Entomologist Emeritus, University of California, Davis

Photos:   All photos by Jack Kelly Clark, University of California Statewide IPM Program.  Used with permission.