Fall (Bug) Colors

October is the heart of autumn in many parts of North Amreica, with intensifying colors of fall foliage. Insects reflect the changing hues of plants, the better to camouflage themselves. As chlorophyll recedes, xanthophyll (yellow) and other carotenoids (orange), begin to manifest. Anthocyanins (reds to purples) become prominent, too. Could it be that insects feeding on those leaves take on the same colors? Perhaps the insects are merely responding the shrinking period of daylight as the leaves are doing.

As leaves begin falling down, alate (winged) citronella ants, Lasius sp., fly up, in hopes of finding mates from nearby colonies.

Greens persisting

This year, here in northeastern Kansas anyway, an exceptionally dry summer has resulted in subdued fall colors. Green leaves persist, even if they are withered from a record-breaking hard freeze last week. Some insects insist on being wholly green, or at least partly so.

A male lesser meadow katydid, Conocephalus sp., basks on a sidewalk.

Green Mantisfly, Zeugomantispa minuta, on the side of our house.

Nymphs of the Pale Green Assassin Bug, Zelus luridus, will overwinter in that stage.

Ah-ha! It is Bristly Roseslug sawfly larvae, Cladius difformis, doing all this damage to our roses.

Straw

Beige is an overwhelmingly common color of fall in pastures and fields, and even lawns thanks to our current drought. Insects of the same color merge seamlessly with grasses and weeds, becoming nearly impossible to detect unless they move. On windy days it is even more of a challenge. Thankfully, for entomologists and bugwatchers, insects frequently alight on, or are blown onto, sidewalks, the sides of buildings, and other surfaces where they stand out.

A Corn Earworm moth, Helicoverpa zea, attracted to a blacklight in our front yard.

This stink bug, Thyanta sp., has highlights of rose and green, too.

A jumping spider, Colonus sp., prowling the exterior of our house.

Yellow and gold

Many insects with warning colors are bright yellow, and black, regardless of the seasons, but in autumn they complement the colors of plants.

A Cloudless Sulphur, Pheobis sennae, pauses in our flower bed.

A Goldenrod Soldier Beetle, Chauliognathus pensylvanicus, in the absence of flowers, looks forlorn on the side of our house.

A worker Eastern Yellowjacket, Vespula maculifrons, lingers on a hosta leaf.

One yellowjacket mimic is this syrphid flower fly, Helophilus sp.

Orange and red

Orange and red are less common colors in insects, and often part of the loud wardrobe of aposematism (warning colors), or mimicry of other insects that are well-defended by venom or toxins. Lady beetles defend themselves by autohaemorrhaging, or “reflex bleeding,” from leg and body joints. An alkaloid toxin in the haemolymph is aromatic and sticky, quite repulsive to would-be predators.

Eastern Comma butterfly, Polygonia comma, will overwinter as an adult, hidden in a crevice in a log, or a similar niche.

Some checkered beetles, like this Enoclerus ichneumoneus, are likely mimics of velvet ants (which are wingless female wasps with a potent sting).

Multicolored Asian Lady Beetle, Harmonia axyridis, is also known as the "Halloween Ladybug" for the time of year it is most conspicuous as it seeks winter shelter on or inside buildings.

Worker citronella ants, Lasius sp., are a lovely orange or yellow.

Metallic colors

Many insects are iridescent, often vividly so. Whereas the preceding colors are expressed by pigments that absorb all wavelengths of light except the one we interpret as brown, beige, green, yellow, orange, or red, or black, iridescent colors are produced by a different mechanism. These structural colors are rendered by micro-sculpturing, and/or layering, of the cuticle of the animal’s exoskeleton. Light bounces and reflects, and the color we see varies depending on the angle of the light hitting the organism.

Many longlegged flies, family Dolichopodidae, have bright metallic colors, and run rapidly over the surface of leaves.

Metallic sweat bee, Augochloropsis sp(?), pausing to groom herself.

"Greenbottle" blow flies are brightly metallic green, copper, or bronze.

"Bluebottle" blow flies, Calliphora sp., are weakly iridescent on the abdomen.

White and multi-colored bugs

A few insects are white, or appear so at least. This is especially the case for true bugs that exude waxy secretions to protect themselves from desiccation and make themselves distasteful to predators. Leafhoppers display almost every color combination imaginable in patterns of spots, blotches, stripes, bands, and speckles.

Whiteflies are not flies, but tiny, wax-dusted relatives of aphids.

Drepanaphis sp. aphids are studded with spikes that help hold in place the white wax they secrete.

A teneral male Familiar Bluet damselfly, Enallagma civile, has subdued, pastel colors compared to the vivid blue it will have eventually.

Versute Sharpshooter leafhopper, Graphocephala versuta, is a tiny living rainbow.

Until next time

Keep looking for colorful “bugs,” deep into fall. Some will enjoy your rotting Jack-O’-Lantern. Others will find their way indoors, preferring the same comfortable climate you yourself enjoy. Meanwhile, I will do my best to keep cranking out blog posts to help you identify them. Stay warm and dry, friends.