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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Eater of eaters of thistles and other plants: Spined soldier bug, Podisus maculiventris


The piercing beak of the spined soldier bug brings the life of a thistle tortoise beetle to an end.


Last week we met two beetles intent on eating thistles in a community garden in central Maryland. While observing these exotic biological control agents, we encountered one of our potent native predators, the spined soldier bug, eating a thistle tortoise beetle, hungry eater of thistles.

On a thistle in a garden, a spined soldier bug drains the life from a thistle tortoise beetle. Once all the fluid is gone the victim is summarily discarded.

And here’s how the spined soldier bug got its name.

Spined soldier bugs are the non-vegan part of the stink bug clan, to which notorious pests such as brown marmorated stink bugs and harlequin bugs belong. Spined soldier bugs are named for their signature identifying character, pointy shoulders located just behind their head. These stealthy predators have an uncanny way of sneaking up on a potential victim, extending their piercing proboscis, jabbing it into the prey and rendering the victim helpless before it can escape. Predatory stink bugs administer digestive enzymes through their beak to pre-digest the victim’s tissues before activating a pump in their head to imbibe the liquid nutrients of their unfortunate victim. Yum!

In addition to snacking on thistle tortoise beetles, spined soldier bugs are known to attack and consume more than 90 other insect species, including some of the most important pests of our agricultural crops such as Mexican bean beetles, European corn borers, and Colorado potato beetles to name a few. Both immature stages, called nymphs, and adults are voracious predators. The fame and utility of these North American predators has made them in demand and they have been imported and released to help manage serious pests of agricultural crops in several European countries.

Alas, spined soldier bugs do not share the human’s fondness for other charismatic insects such as monarch caterpillars, a favorite of conservationists in Maryland and across the United States. In the bug-eat-bug natural world, regardless of human concern, the next meal for the spined soldier bug may be just about any tasty insect only one beak away.

A sneaky soldier bug discovers a butterfly in its most vulnerable stage, the chrysalis.


Oh no, not the monarch!

Bad day for a tomato hornworm. Not only have the lethal parasitic wasps emerged from their cocoons lining the back of the larva, but a spined soldier bug has also arrived to have a little liquid refreshment from the dying caterpillar.


Bug of the Week consulted the wonderful “Featured Creatures” website of the University of Florida, “Common name: spined soldier bug: Scientific name: Podisus maculiventris (Say) (Insecta: Hemiptera: Pentatomidae)” by David B. Richman and Frank W. Mead, to prepare this episode.

We thank our friends at the Howard Conservancy for providing the opportunity to observe spined soldier bugs at work and Dr. Shrewsbury for a delightful image of these interesting herbivores.