The soldier beetle is a common sight in summer gardens across much of North America. These insects, also known as leatherwings, are surprisingly good for the garden. They’re often spotted feasting on the nectar and pollen of summer-blooming plants, but they are also keen predators of several garden pests. In this article, I’ll share details about this fascinating beneficial insect and introduce ways you can encourage their presence in your garden.
What is a soldier beetle?
Soldier beetles are in the family Cantharidae. There are around 470 different species worldwide, many of which are in the genus Chauliognathus. All species of the soldier beetle are soft-bodied with pliable, leathery-like wing covers (called elytra). The family gained the common name of soldier beetles because one of the first members of the family to be described was bright red, reminding the discoverer of the British red coats. Soldier beetles look a lot like their close cousins, the fireflies, but they don’t produce the signature glow.
The adult beetles are some of the most commonly encountered predatory beetles in backyard habitats, especially during the late-summer months of July, August, and September. They are fascinating and gorgeous creatures with an incredible diversity of physical attributes, depending on the species. Their importance in managing garden pests is of great value. Adult beetles are quick insects, and they readily fly away when disturbed.
How the soldier beetle benefits your garden
Soldier beetles are considered beneficial for two reasons. First, the adults are important late-season pollinators. They move pollen from one flower to the next as they feed on the nectar. Secondly, the adults of some species eat prey such as aphids and other small insects. In addition, their predatory larvae feed on grasshopper eggs and the eggs of other insects, snails, slugs, newly hatched grasshoppers, and the caterpillars of various moths, among other pest insects. The larvae live on the ground beneath fallen leaves and in damp soil, as well as under mulch and other organic debris. Occasionally, they can also be found under the loose bark of decaying logs and branches.
Each soldier beetle passes through four life stages during its life cycle and undergoes a complete metamorphosis. As the insect matures, it passes from egg to larva then to a pupa and eventually emerges as an adult.
What does a soldier beetle look like?
Like all larvae of beetles, the larvae of leatherwings look nothing like the adults. Think about how different a lawn grub looks from an adult Japanese beetle and you’ll get the idea. Soldier beetles spend between 1 and 3 years as a larva, depending on the species.
Soldier beetle larvae have a felt-like exoskeleton. They have almost a suede-like look to them and are black to gray in color. Their shape looks a bit like the Very Hungry Caterpillar because they have a rippled look to them due to each of their body segments being separated by an indentation. The larvae feed primarily at night and are fast movers with grasping jaws that capture their prey.
Like other true beetles, adult soldier beetles have two forewings which create a shield over their soft hindwings. Each wing cover is colored in a distinct way according to which genera and species it belongs to. Some are orange and black, others are red, black, or brown with various markings. Their long legs are another distinguishing feature. Also, leatherwings have heads that protrude out from their bodies, while the heads of fireflies are tucked beneath their thorax.
Overwintering takes place as dormant larvae under debris. In spring, the larvae become active, feeding on insects in the leaf litter and top layers of the soil. They pupate in early summer with the adults emerging in July. You’ll find the adult beetles in your garden from late summer through fall, during which time the female soldier beetles mate and then lay eggs into the soil. The eggs soon hatch and the larvae feed until the arrival of cold weather when they switch into dormancy.
Male and female leatherwings can often be spotted mating while feeding on nectar and pollen in the late summer garden.
Common species of soldier beetles
As mentioned, there are around 470 species of soldier beetle. In the eastern and midwestern U.S., the orange and black Pennsylvania leatherwing (Chauliognathus pennsylvanicus), also called the goldenrod solider beetle, is a common sight. The Pennsylvania leatherwing is a half-inch-long, with tannish-orange wing covers that have an elongated black spot at the base of each of them. Another black spot is located behind the head.
In the west, the brown leatherwing is more common. Other species include the margined solider beetle (C. marginatus), which is active earlier in the season and has more of a black streak than a black spot on their wing covers. The larvae of the margined soldier beetle is known to prey on corn earworms and corn borers, making it a friend of backyard gardeners and farmers alike. The Colorado plains soldier beetle (C. basalis), which is a species common to the central plains, has a darker orange color and bottle-shaped black markings on the wing covers.
How to attract predatory soldier beetles
There are a few different things you can do to support a healthy population of soldier beetles in your garden. First, provide plenty of nectar sources. If you can keep the bees and butterflies happy, you can keep these predators happy, too. Late-blooming plants are key to the survival of leatherwing beetles since they are in bloom during breeding and egg laying. Goldenrod, asters, Joe Pye weed, Boltonia, Coreopsis, and other late-season perennials are excellent additions to the garden. Flowers in the Asteraceae family tend to be particularly prized, and since soldier beetles are most attracted to yellow and orange flowers, good choices include zinnia, marigold, and sunflower blooms.
In addition to providing a food source for the adults, you can help support larval soldier beetles by leaving the leaves in place throughout your flower beds. Instead of conducting a fall clean up, let the garden stand through the winter and keep the fallen leaves in place over the soil as a mulch year-round. Here’s more about conducting an insect-friendly garden clean up.
You’ll also want to eliminate the use of synthetic chemical pesticides that could bring harm to these wonderful creatures. Systemic pesticides are particularly detrimental to these and other good bugs and pollinators because they travel through the plant’s vascular system and often end up in the pollen and nectar.
Predatory beetles – why you want them around
In addition to soldier beetles, there are thousands of other types of predatory beetles you should encourage in your garden, including ladybugs, fireflies, and rove beetles. Most of these feed on nectar and pollen from the same plant species as soldier beetles, so you’ll be benefiting lots of good beetles in addition to the leatherwings. As either adults or larvae (or both!) predatory beetles are responsible for controlling dozens of different garden pests, from cabbageworms and squash bugs to slugs and corn earworms, predatory beetles help manage them all.
Do soldier beetles harm humans or pets?
Both adult and larval soldier beetles of some species can exude foul defensive chemicals when they are threatened by other predators (or hapless humans who accidentally mishandle them!), but they do not bite people or animals. Soldier beetles do not eat plants, mar foliage, or bring harm to the garden. They are beneficial insects that should be supported and nurtured.
Now that you know more about the fascinating and very helpful soldier beetle, I hope you’ll be on the lookout for them in your own garden. If you see them, you can consider it a sign of a happy, healthy, balanced garden that is welcoming to all creatures.
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