ID Tip: Seven-spotted or Nine-spotted Lady Beetle?

Today's identification tip involves separating two nearly identical lady beetles: the Seven-spotted Lady Beetle, Coccinella septempuncta, introduced from Europe, and the native Nine-spotted Lady Beetle, Coccinella novemnotata. There is widespread speculation that the exotic Seven-spotted ("C-7") has displaced the native Nine-spotted ("C-9"), and indeed the latter species has become noticeably scarce over most of its former range, especially in the eastern U.S., over the last 35 years or so. That is why it is critical to be able to identify C-9 and report sightings to the Lost Ladybug Project.

Typical specimen of Seven-spotted Lady Beetle ("C-7")

Physical Features

The most dependable, though subtle, difference between these two species is found on the front edge of the pronotum (top of thorax). In the Seven-spotted Lady Beetle, only the corners, or "lapels" if you will, are white. The remainder of the pronotum is black. In the Nine-spotted Lady Beetle, the entire pronotal "collar" is white, so the front edge of the pronotum is white, from corner to corner.

Specimen of the Nine-spotted Lady Beetle ("C-9")

Meanwhile, the wing cover (elytron) of the Nine-spotted Lady beetle does bear an extra black spot, located near the "shoulder." This spot can, however, be vague or even obsolete. The markings on the pronotum are much more consistent.

The Nine-spotted Lady Beetle is usually slightly smaller than the Seven-spotted, and is more often a creamy orange in contrast to the brighter orange, or red, of C-7. Both species are polished (shiny) in texture, and highly convex or nearly hemispherical in shape.

Heavier spots on this C-9

Behavior

There is little difference in behavior between these two species. Both are predators of aphids and can be found on plants hosting aphid colonies.

Another example of the Nine-spotted Lady Beetle

Habitat

Habitat is not a good way to distinguish these two lady beetles, either. Both occur in a variety of ecosystems, from vacant lots, yards, gardens, parks, and forest edges to orchards and agricultural fields.

Complicating Factors

A nearly spotless form of the Multicolored Asian Lady Beetle

There are a surprising number of nearly identical lady beetle species, and simply counting the spots is a very unreliable way of making an identification. There is extreme variability in many species, especially the abundant Multicolored Asian Lady Beetle, Harmonia axyridis, which is yet another non-native ladybug. Not only does the number of spots on the elytra vary, but so do the markings on the pronotum. This species needs to be ruled out before you try and conclude whether your specimen is a C-7 or C-9.

Transverse Lady Beetle

Here in the western U.S., we also have the Transverse Lady Beetle, Coccinella transversoguttata, which resembles C-7 except that the spots on the elytra near the pronotum are connected to form a horizontal black bar between the "shoulders." The Transverse Lady Beetle also appears to be suffering in the wake of C-7's arrival.

Quiz Photo: Which species is this one?

Please keep a lookout for the Nine-spotted Lady Beetle where you live and during your travels. The more eyes in the field, the better will be our understanding of the status of this species, which has been the state insect of New York since 1989. Thank you.

Insidious Insect Fungi

The Walking Dead is a popular television show these days, but reality is perhaps even more sinister. Did you know that there are fungi that hijack the brains of insects causing them to behave in ways that benefit the fungus? It's true, and you have probably seen evidence of this macabre life cycle without knowing the answer to the mystery.

Fly infected with fungus attached to a leaf (Massachusetts)

Cheryl Harner, a naturalist and writer at Weedpicker's Journal, asked me about this bizarre phenomenon a couple of years ago, and I always meant to learn more about it myself. You owe it to yourself to check out her blog, and I'll try to complement her post rather than compete with it. She did an excellent job of researching and linking, though.

Dead grasshopper nymph that has climbed a grass stem due to funal infection (Massachusetts)

It is not just grasshoppers and ants that are victimized by what are called "entomopathic" fungi. Flies are among the most conspicuous of hosts. You have probably seen flies clinging to foliage or twigs in odd, contorted positions, with bloated abdomens. The spores of the Entomophthora muscae fungus have their hosts literally bursting at the seams, the membranes between the abdominal segments.

Meanwhile, grasshoppers and related orthopterans are plagued by Entomognatha grylli, and lady beetles are often afflicted with Laboulbeniales fungi.

The life cycle of fungi in the order Entomophthorales begins when a spore lands upon an insect. However, many of the fungi are very host-specific, so if a spore lands on the "wrong" bug it is likely done for. Should the spore contact the correct host, it soon germinates, penetrating the cuticle of the insect and growing internally, absorbing the host's nutrients, eventually killing it. Before the doomed creature perishes, the fungus does something remarkable. In many cases it stimulates the host to seek a high point, either by climbing or flying, whether or not the insect normally performs such behavior. This phenomenon is sometimes referred to as "summit disease."

Headless grasshopper corpse in wake of fungal infection (Colorado)

Once the host insect ascends a grass stem, for example, the fungus sends out special structures called rhizoids that are white, thread-like filaments. These fibers often emerge from the insect's tarsi ("feet") or mouthparts, anchoring the bug to the substrate such that it is not easily dislodged after death. Now the spores erupt, sometimes in the form of fruiting bodies like other fungi, or simply exuding from holes in the host's cuticle.

Carolina Leafroller ("cricket") showing fungal rhizoids penetrating its feet and anchoring it to the leaf (Ohio)

Grasshoppers are among the most conspicuous victims if only because of their size, but most types of insects, and spiders, too, are vulnerable to fungal infection. The typical appearance of fungus victims are stiff, dessicated specimens that are essentially mummified.

Harmonia axyridis with perithecia of Hesperomyces virescens at the tip of its wingcovers (elytra)

Fungi in the order Laboulbeniales affect beetles in particular, and are very different in their mode of dispersal and effect on the host. Hesperomyces virescens apparently afflicts only the Multicolored Asian Lady Beetle, Harmonia axyridis, at least here in North America. It is microscopic, and is essentially a sexually transmitted disease since the overwhelming means of infection occurs during mating of the host. Spores can also transfer when large groups of overwintering lady beetles force the insects to rub against each other.

Mating pair of Harmonia axyridis in Illinois exhibiting symtoms of Hesperomyces virescens

Most adult beetles exhibit symptoms in the form of tiny, yellow, scale- or flake-like protrusions from the cuticle, especially at the tip of an elytron (wing cover). These are the fruiting bodies, called perithecia, from which spores are issued, if I comprehend the literature and language of mycology correctly. Interestingly, the fungus has little or no effect on the host, but depends on it for reproduction.

When one thinks of mortality factors that affect insects, or most other animals, we tend to forget the impact of fungal organisms. Maybe I have seen one too many episodes of the television show Monsters Inside Me, but I have a whole new respect for fungi now. It helps to remember that fungi are often very host-specific, so handling a fungus-ridden bug is not going to pose a health threat to a human. As far as we know.

Fungus-infected fly corpse on leaf (Colorado)

Sources: Eiseman, Charley and Noah Charney. 2010. Tracks & Signs of Insects and other Invertebrates. Mechanicsburg, Pennsylvania: Stackpole Books. 582 pp.
Parker, Abigail M., et al. 2010. "with Labioulbeniales fungus," Bugguide.net.