In the world of garden friendly bugs, ladybugs have become the polka-dotted poster children. Unless you’ve been hiding under a rock, you know how good ladybugs are for the garden, and you may think you already know everything there is to know about them. But you’d be wrong.
First off, there are over 480 different species of ladybugs in North America and many of them aren’t red with black polka-dots. A significant number of species have completely different coloration. These garden friendly bugs can be brown, yellow, cream, orange, black, gray, burgundy, or pink. They can have lots of spots or no spots at all. They can be striped, banded, or mottled. They can even have blue eyes. The checker spot ladybug in the featured photo is a good example of a common ladybug that’s certainly not red with black polka-dots. But, regardless of their physical appearance, all ladybug species have these five things in common.
5 Surprising facts about ladybugs
- Fact #1: Ladybugs have stinky feet. You probably already know that nearly all ladybug species are predaceous as both adults and larvae. They consume a broad diversity of prey, including aphids, scale, mites, mealybugs, small caterpillars, insect eggs and pupae, whiteflies, mites, and psyllids. But, did you know that ladybugs leave behind a chemical footprint as they walk around looking for their prey? This footprint is a type of volatile odor known as a semiochemical, and it sends a message to other insects. When another predatory insect is out hunting for prey on the same plant the ladybug was traipsing around on, it “smells” the ladybug’s foot print and may decide not to lay eggs anywhere nearby, just to keep those eggs from being eaten by the ladybug too. For example, the stinky feet of a ladybug may keep parasitic wasps from laying eggs in aphids because the female wasp doesn’t want her offspring to be eaten right along with the aphids.
- Fact #2: Ladybugs eat other ladybugs. A process known as molecular gut-content analysis allows scientists to find out who is eating who in the garden. As crazy as it sounds, since you can’t ask a bug what it had for dinner, scientists examine the DNA found in the digestive system of beneficial insects instead. This helps them learn about what ladybugs (and other garden friendly bugs) eat. A team of scientists found that more than half of the ladybugs collected in a field of soybeans had remnants of other ladybug species in their guts. Many of them had ingested multiple species. When one good bug eats another good bug, it’s called intraguild predation (IGP), and it is a routine occurrence in your garden. Needless to say, the dining habits of ladybugs are a complicated affair.
- Fact #3: You’ll never see most ladybug species… unless you like to climb trees. Though many of North America’s ladybugs are generalist predators who eat whatever prey they can catch, there are also a plethora of specialist species who can only consume just one particular species of adelgid, mealybug, or mite. In order to survive, these specialist ladybugs must live in the particular tree that hosts the species of insect they consume. But, even among ladybugs who can feed on a broad diversity of insect prey, there are dozens of species that spend their entire lives in the tree canopy. You’ll almost never see these tree-dwelling, garden friendly bugs, unless you’re an arborist… or a monkey.
- Fact #4: Native ladybugs DO NOT spend the winter in your house. The ladybugs that enter homes and other structures to overwinter are an introduced species, the Asian multicolored ladybug (also called the harlequin ladybug). All native ladybug species spend the winter outdoors, in leaf litter, under tree bark, in natural crevices, or, in the case of the convergent ladybug, they migrate and hibernate by the thousands on mountaintops in parts of the American West. Native ladybugs do not overwinter in houses. Unfortunately, non-native, Asian multicolored ladybugs far outnumber native ladybug species in many parts of North America. And, in fact, these ultra-competative, exotic ladybugs may be to blame for the dramatic decline in many native ladybug species (you can read more about that here).
- Fact #5: The ladybugs you buy in the store are wild-collected. Before you buy garden friendly bugs, such as ladybugs, and release them into your garden, you need to think about where they came from. Almost all of the live ladybugs you find for sale at your local garden center were harvested from the wild. After migrating for hundreds of miles, the convergent ladybugs I mentioned in Fact #4, gather together to spend the winter on sunny mountaintops. These hibernating insects are “harvested” with backpack vacuums; they are then packaged into containers and shipped around the country for sale at your local garden center. This practice disrupts natural populations and may spread disease and parasites to garden friendly bugs in other parts of the country (Imagine if we did this with another migrating insect – the monarch! We would be up in arms! So, why aren’t we up in arms about these wild-collected ladybugs?).
Ladybugs: Garden friendly bugs worth knowing
As you can see, ladybugs are full of surprises. If you’re interested in learning even more fascinating facts about these awesome little pest-munchers, we have a few other posts you might want to check out:
Tell us, have you found ladybugs in your garden? Share a photo in the comment section below.