Thanks to Pat Nelson’s sharp eyes, I realized I had mislabeled the bug in yesterday’s blog. It was an Ambush Bug, not an Assassin Bug. While both are predators and in the same family (Reduviidae), Assassin Bugs are usually dark colored and have long, narrow heads compared to Ambush Bugs. Ambush Bugs are usually quite stout and typically have bright colors such as yellow, red or orange. They also have thickened front pincer-like legs with teeth-like structures that hold the prey while it is being consumed. Although small (usually less than ½ inch), an Ambush Bug’s prey may be as large as a bumblebee, wasp or butterfly.
Although the term “bug” is commonly used to refer to just about any insect, there is a specific order of insects (Hemiptera) that are considered “true bugs” and allies. All insects in this order possess a syringe-like beak that they use to suck the liquefied contents out of plants or animals. Their lower lip forms a sheath that contains four blades. One pair of blades (mandibles) is for cutting and the other pair (maxillae) is for spitting and sucking. The maxillae combine to make a tube with two channels, one for sucking food up and the other for spitting saliva (containing enzymes that dissolve tissue) back into the food.
Some of the insect-eating true bugs may be familiar to you – assassin bugs, ambush bugs and damsel bugs (named for their diminutive size) are among them. Nabicula subcoleoptrata (pictured) is a common black, ant-like damsel bug known for its aggressive predation. Look for it in meadows, where it frequently preys on an introduced bug, the Meadow Plant Bug (Leptopterna dolabrata). In this photograph, it has successfully preyed upon and consumed a small larva, identity unknown.
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Every year I receive questions about this unusual-looking insect which is often found on and in houses in the fall. As a result, I publish a post about it every couple of years. For those of you with good memories, please excuse the repetition.
Roughly 30 years ago Western Conifer Seed Bugs (Leptoglossus occidentalis) started moving east. They are now well established coast to coast. Here in the East they seek shelter during the winter, often choosing to share our domiciles with us. Fear not – though they look fairly menacing, they will do you no harm. Western Conifer Seed Bugs do not bite or sting, and in their semi-dormant condition they do not feed or breed. If you choose not to co-habit with these bugs, be forewarned. When disturbed, they can emit a noxious smell.
In the spring they will vacate your house and feed on the sap of the young cones and flowers of conifers, including Eastern White Pine, Red Pine, Scotch Pine, White Spruce and Eastern Hemlock. Mating takes place, eggs are laid and the young nymphs feed on conifer seeds which they find by detecting the infrared radiation that the cones emit.
These bugs are also called “leaf-footed bugs,” and if you look at their hind legs you will see that a section, the tibia, is flattened. Some species display this specialized leg structure during courtship, and others may use it for defense purposes.
Ambush bugs, a type of assassin bug, are true bugs, in the order Hemiptera. (Although insects are often referred to as “bugs,” technically only insects in this order are classified as bugs by entomologists.) All true bugs have piercing and sucking mouthparts, and wings which are membranous and clear at the tips, but hardened at the base.
Ambush bugs are usually brightly colored (yellow, red or orange) and have thickened front legs which are used to capture prey up to ten times their own size. They live up to their name, patiently lying in wait for unsuspecting prey, often in goldenrod flowers where they are very well camouflaged. An ambush bug, upon sighting an insect, suddenly seizes the prey in its powerful forelegs and quickly dispatches it with a stab from its sharp beak. It then injects digestive enzymes into its prey, after which it drinks the resulting liquid innards.
Monarch larvae aren’t the only insects equipped to feed on the toxic cardiac glycoside-filled leaves of milkweed. Milkweed Tussock Moth larvae also dine on them, avoiding veins due to the latex-like, sticky white sap that could glue them in place. When they first hatch, Milkweed Tussock Moth larvae tend to stick together in “herds,” all feeding on the underside of the same leaf. This behavior provides a gold mine for predators such as predatory stink bugs (pictured) that discover them. Unlike their (plant) sap-sucking stink bug relatives, predatory stink bugs feed on more than 100 species of insect pests, often attacking insects much larger than themselves, drinking their body fluids with their needle-like beak. (Photo taken and kindly donated by Chris Doyle)
You may have noticed ½-inch-long black insects with red markings emerging from cracks and crevices inside or outside your home with the recent arrival of warmer weather. These are adult Boxelder Bugs that have been hibernating all winter and have become active with the warming days. They may disappear on days such as today when the weather turns cold again, but they’ll emerge for good in late April or May, just about the time buds on Boxelder trees are beginning to open.
During the spring and early summer they seek out and feed on low vegetation and seeds on the ground. Starting in mid‑July, they move to female seed-bearing Boxelder trees (or occasionally other maple or ash trees) where they lay eggs on trunks, branches, and leaves. Red nymphs hatch in roughly two weeks, and proceed, like their parents, to feed on Boxelder foliage and seeds by using their piercing-sucking mouthparts. Even if their numbers are large, there is no noticeable feeding injury to these trees. Come fall both adults and nymphs congregate in large numbers on the south side of trees, buildings and rocks exposed to the sun (only adults survive the winter) before settling in a protected hibernaculum. Boxelder Bugs are most abundant during hot, dry summers followed by warm springs. They do not bite people and are essentially harmless to property. (Photo: adult Boxelder Bugs in spring; insert – adults and nymphs in fall) Thanks to Jeannie Killam for photo op.
White-margined Burrower Bugs (Sehirus cinctus) are true bugs, members of the order Hemiptera. The red and black bugs in this photograph are immature nymphs and have molted once. Their coloring serves as a warning to would-be predators that they are at the very least distasteful, and possibly poisonous. Adult White-margined Burrower Bugs are roughly ¼” long, and black with a white margin (not visible in photo) along the edges of their forewings.
These bugs feed on the seeds of plants in the mint and nettle families. Being true bugs, they feed not by chewing but by piercing seeds with a sharp beak, injecting digestive enzymes, and then sucking in the partially digested food.
White-margined Burrower Bugs are fairly unusual for non-social insects in that the mothers provide care and provisions for their young, much like social insects such as ants, paper wasps and honeybees. The adults dig shallow burrows into which they place a supply of seeds and lay between 120 and 150 eggs next to the seeds. They guard their eggs and brood and bring more seeds as needed for 1-3 days after the eggs hatch. At this point, the young bugs can forage for themselves.
Adults dig down into the leaf litter in late fall, where they overwinter and emerge next spring ready to mate. If you see a large cluster of White-margined Burrowers Beetles, do not be alarmed, as they do not bite nor are they interested in eating anything but species of mint and nettle.