Ladybugs are familiar insects, easily recognized by their distinctive, rounded bodies and vibrant coloration, particularly their spots. These small beetles are a common sight in gardens and natural spaces.
The Truth About Ladybug Spots
The number of spots on a ladybug is not fixed; it varies significantly by species. These markings serve as a key identifier for entomologists.
For example, the Seven-spotted ladybug (Coccinella septempunctata) consistently features seven black spots. In contrast, the Two-spotted ladybug (Adalia bipunctata) typically displays two. Some species, like the Convergent lady beetle (Hippodamia convergens), can have a variable number of spots, from a few to thirteen. There are even ladybug species with no spots, and the 24-spot ladybug (Subcoccinella 24-punctata) has twenty-four.
Spotting the Differences: Ladybug Species and Their Markings
The Coccinellidae family, to which ladybugs belong, encompasses over 5,000 species globally and more than 450 in North America. This diversity extends beyond just spot counts.
Ladybugs come in a wide spectrum of colors, including red, orange, yellow, and black. Their markings also differ greatly, appearing as unique patterns, stripes, or sometimes no spots.
For instance, while the bright red, seven-spotted ladybug is a common image, other species present entirely different appearances. The Twice-stabbed ladybug (Chilocorus stigma) stands out with its shiny black body with two prominent red spots. The Two-spotted ladybug (Adalia bipunctata) can exhibit various color forms, including melanic forms that are black with four or six red spots. This wide range of colors and patterns underscores that ladybug identification involves more than simply counting spots.
Beyond the Spots: What Ladybug Markings Tell Us
The vivid colors and distinct spots on ladybugs serve a biological purpose: they act as a warning signal to predators. This defense mechanism, known as aposematism, indicates the ladybug is unpalatable or toxic.
Ladybugs produce defensive chemicals called alkaloids, making them taste foul to predators. When threatened, they can also exude a yellowish fluid, a process called reflex bleeding, further deterring attackers.
Research indicates that the intensity of a ladybug’s color can correlate with its toxicity, with brighter individuals often possessing higher concentrations of these compounds. A common misconception is that the number of spots indicates a ladybug’s age. This is not true; the number of spots is genetically determined and remains constant throughout the beetle’s adult life.
Ladybug Look-Alikes
Distinguishing true ladybugs from similar-looking insects can sometimes be challenging for the average observer. The Asian lady beetle (Harmonia axyridis) is a particularly common look-alike, often mistaken for native ladybug species. However, there are several key features that can help tell them apart.
One of the most reliable indicators is the presence of an “M” or “W” shaped marking on the white area directly behind the Asian lady beetle’s head, which is typically absent in native ladybugs. Asian lady beetles also display a greater variation in their appearance, with colors ranging from orange to yellow to red, and spot counts from none to over twenty. Furthermore, Asian lady beetles are generally slightly larger than most common ladybugs and have a tendency to aggregate in large numbers indoors during cooler months, a behavior less common for native species. They may also release a foul-smelling yellow liquid or even deliver a small bite if disturbed.