Insects that Mimic Ladybugs

In nature, creatures that mimic other creatures always arouse suspicion, for a brightly colored marking quickly becomes the jaws of the beast. Defensive mimicry, used in defense against predators, is far more innocuous than aggressive mimicry, a tactic intended to lure in prey, fooling hapless victims into lowering their guard, up until the moment they are eaten alive. 

Long before crocodiles and alligators swam in pellucid waters, Suchomimus, the “crocodile mimic,” dominated the waterways, using its rows of serrated teeth to snatch massive fish from the rivers of Cretaceous Africa.

Mimicry extends to subtle forms, including the lesser order of insects. You may be excited to find an oddly colored lady bug, only for it to secrete a foul-smelling fluid. While native ladybugs are docile icons of good fortune that eat garden pests and mind their business, the Asian lady beetle (Harmonia axyridis) is an aggressive imposter that invades houses. 

 

Asian Lady Beetles: The Main Culprit

The Asian lady beetle is known by several names, including harlequin ladybird and Halloween beetle. Many relatives share similar physical traits – there is rarely a case in which siblings are so dissimilar that people would believe they are adopted. Still, shared blood doesn’t account for radical personality shifts between cousins. 

Lady beetles operate the same way: they share the same family as ladybugs, yet they have gone off track. Originally introduced to control crop pests, the Asian lady beetle has become a bit of a nuisance. While they do eat aphids, they also have a nasty habit of biting humans and trashing houses in swarms when the weather cools down. When these little monsters get startled – which happens when they sense a threat – they perform a defense mechanism called reflex bleeding, exuding a foul-smelling, toxic yellow fluid from their leg joints.

The artifice lies in their varied color forms, from the usual bright red to the rarer black, leading the gardener to mistake them for a funky ladybug; even an entomologist can be duped at times. Though they are technically invasive, it should be noted that they rank second in comparison to more noxious pests, including spiders, termites, or rats. 

Here’s a guide to differentiate the two: 

Dealing with an Infestation

During the fall, lady beetles congregate in large numbers, seeking warm hideouts before a cold front arrives. They are more prone to invading older dwellings, such as an old house in the woods – the cracks, crevices, and deteriorating seals are a welcome mat for their numbers. Instead of squishing or swatting them, simply vacuum them up. To prevent them from returning in the fall, seal the exterior entry points of your home using caulk and check that all your window, door, and vent screens are secure.  

Other Ladybug Mimics

The False Ladybird Beetle (Endomychidae)

Unlike Asian lady beetles, their falsehood can be spotted much more easily by anyone who doesn’t have a vision impairment. Though they plagiarize the classic red-and-black color palette, they are much less rotund and bear fewer spots. Their lifestyle also diverges from that of ladybugs. Instead of hunting down garden pests, false ladybird beetles feed primarily on fungi, rotting wood, and lichen.

The Bean Leaf Beetle (Cerotoma trifurcata)

If you are trying to grow green beans, soybeans, or peas, the bean leaf beetle is a common agricultural pest that behaves insolently, leaving devastating, ragged holes in your plant leaves. Their elongated shape and lackadaisical color, often tan or a rust red, give them away. Their spots are also shaped more like square blocks or rectangles along the margins of their wings, rather than the neat, circular polka dots found on a traditional ladybug.

Protecting Your Backyard

Mistaking a destructive leaf beetle for a helpful ladybug is one of the easiest pitfalls a gardener can experience – your ignorance is their power. If you see a spotted round beetle and automatically assume your plants are safe, you might inadvertently allow your local pest population to explode.

Take an extra few seconds to lean in close. Look for the shape of the spots, check the design behind the head, and observe what the insect is actually doing. If it chugs along merrily, displaying a weaponized ignorance towards your vegetables, you are likely looking at a friendly compatriot. If it is contentedly chewing a hole straight through your prize foliage, needless to say it’s obviously time to intervene. By learning to navigate these subtle visual cues, you can effortlessly protect your blooms and ensure your garden remains a thriving sanctuary.

As an extra precaution, organic insecticides and row covers are effective at deterring pests. In the winter, greenhouses keep your crops and prized specimens readily insulated from freezing weather conditions.