Many people are familiar with the bright red ladybug with black spots. As with everything in nature, this appearance has a purpose. The patterns and colors on the bodies of ladybugs remind would-be predators of the unpleasantness they experienced the last time they tried to kill a ladybug with its colorful appearance.
Red with black spots is not the only color scheme for ladybugs, which are beetles. Other color combinations are yellow with black spots, black with white spots and dark blue with orange spots, according to Michael E.N. Majerus in his essay on ladybugs in the "Encyclopedia of Insects." The number of spots varies by species. Some ladybugs have two spots; others seven.
Still other species, like Cocconella novemnotata, have nine spots, four on each of its two forewings and one that straddles each forewing at the top of its body. The species Hippodamia convergens has up to13 spots. The ladybug with the common name checker-spot ladybug has 14 non-circular markings. Common in the United States is the Asian ladybug, which can have as few as two red spots on a black body or as many as 19 black spots on an orange body. Other body colors for the Asian ladybug include mustard and red.
The color patterns on some ladybugs living in reeds change according to the season. In the fall and winter, these ladybugs are beige with black spots, blending in with the brown of the reeds and making them difficult for predators to see. In the spring they turn red, giving bold notice to predators.
To defend against predators, ladybugs discharge hemolymph, a bad-smelling, bitter-tasting fluid from the pores of their jointed legs. The release of hemolymph is called reflex bleeding.
Chemicals released by ladybugs during reflex bleeding include cardiac glucosides (chemicals with the same properties as medication prescribed for those suffering from heart failure), alkaloids, histamines, pyrazines and quinolenes. Some of these chemicals come from the food the ladybugs eat, others from substances occurring naturally in their bodies.
Odor, Potency and Color
Jacek A. Koziel, an expert in livestock odor, headed a team at Iowa State University that studied ladybug hemolymph. He reports that it smells like a nutty mixture combined with "green bell pepper, potato and moldy odors." He also notes that the orange beetles under study released more of the stinky fluid than yellow beetles.