Butterfly collectors have known for over a century that the background color of the environment can affect the color of the chrysalis (pupa) of some species of butterfly. The Black Swallowtail butterfly, Papilo polyxenes, has a range of color morphs from light green to dark brown. On green foliage, the pupa is a light green color. On dark stems (often in the fall) the pupae are brown. The color variation helps the pupa better blend into the environment and provides some measure of protection from predators.

How does the Black Swallowtail know how to match the color of its pupa to the environment? Caterpillars have photo receptors (stemmata) with pigments that presumably can detect the surrounding color when it starts to pupate. The color triggers or inhibits the release of a hormone that controls pupal coloration. High levels of hormone will produce a brown pupa, low levels produce a green pupa. Injection of caterpillars on a green background with a nerve extract from caterpillars that are on a brown background will produce brown pupae.

Adjusting their color so they are harder to detect helps Black Swallowtail pupae avoid predation.

Green Form of the Black Swallowtail Chrysalis

The Gulf Fritillary, Agraulis vanillae, feeds on vines in the Passion Fruit family, including Passion Fruit vines. Several species of Passiflora vines are cultivated as garden ornamentals in many parts of the Unites States. The Gulf Fritillary has expanded its range to include those areas where gardeners plant vines that can serve as food for larvae.

In the early 1970s, the Gulf Fritillary range was expanded to the Hawaiian Islands. The Gulf Fritillary was intentionally introduced as a possible biological control agent for the banana poka, Passiflora mollissima, an invasive weed from Central America that is one of the worst forest pests in Hawaii.

The Gulf Fritillary, failed to provide adequate control of banana poka but does feed on other species of Passiflora. The Gulf Fritillary is now established in Hawaii where it feeds on species of Passiflora, other than P. mollissima. In some parts of its range, the Gulf Fritillary is considered a pest because it destroys the Passion Fruit vines.

On a trip to the island of Hawaii in 2006, I photographed this Gulf Fritillary resting on the ground.

Gulf Fritillary

Morpho butterflies are a brilliant blue color because they reflect only the blue wavelength light. Longer light wavelengths are scattered. How does this work? The scales on the wings of Morphos have micro ridges that are spaced close together. The distance is shorter than the longer light wavelengths. When red or green light hits the scale, much of the light that is reflected at the surface collides with a nearby micro ridge. Most of the blue and UV light, which is shorter wavelength light, is reflected by the wing scale without hitting the ridges. The shorter light wavelengths “fit” between the ridges and are reflected. The longer light wavelengths do not fit and are absorbed or scattered rather than reflected.

New technology and improvements in fabrication methods are leading to a new wave of nano scale products. Two-Photon Polymerization is a technique for creating nano scale structures using femtosecond lasers. A brief, focused pulse of light applied to a photosensitive material can create structures in the 100 nm range. Using Two-Photon Polymerization it is now possible (still very expensive and time consuming) to produce synthetic materials that have some of the structural color properties of butter fly wings.

Place your advance order for butterfly wall paper today. Delivery will be at least a decade off.

Structural Blue Color on Morpho Butterfly Wings

Caterpillars, the immature larval forms of butterflies and moths have several styles of movement. Caterpillars of the family Geometridae are called loopers or inchworms. Loopers move by grasping the surface (usually a branch or stem) with their three pairs of tiny thoracic legs. The caterpillar then makes a loop with its abdomen, bringing the end of its abdomen next to the thoracic legs. The end of the looper abdomen has “prolegs”, extensions of the abdominal wall that can grasp a stem or limb. The end of the proleg has hooks called crochets that can hook into the surface of the plants. The looper can grasp the stem with only its abdominal prolegs. This allows the caterpillar to swing its head and thorax away from the end of the abdomen and move forward.

Loopers typically have a relatively thin abdomen that can form loops. Caterpillars with a thick abdomen can not easily form a loop. These caterpillars will move in a forward wave-like motion. The prolegs on the end of the abdomen move first. successive prolegs release, then move forward. When the wave reaches the thorax, the legs will release and move forward form back to front to continue the wave.

Loopers Move By Arching Their Abdomen

Some species of plants brought to North America from other locations become invasive. Invasive species not only establish, but displace many of the native species of plants. Invasive plants can create shade and prevent native plants from getting the sunlight they need to grow. One example is Chinese privet, Ligustrum sinense. In parts of Northern Georgia, Chinese privet is the dominant shrub that excludes many species of flowering plants.

Butterflies use flowering plants as sources of nectar as adults. Butterfly larvae (caterpillars) often depend on one or only a few species of plants for food. How much do invasive plant species such as Chinese privet affect butterflies?

In a recent paper, James Hanula and Scott Horn describe several methods of Chinese privet removal and the affects in following years on butterfly numbers and species composition. They found that privet removal by all means enhanced butterfly abundance, diversity and evenness. The greatest affect was achieved when the privet was mulched after it was cut. Privet removal had noticeable affects on plant species composition.

Pearl Crescent Butterflies Are Affected By Invasive Plant Species

Cut open a potato and leave it exposed to the air. The potato will turn from white to brown. This is due to an enzyme, polyphenol oxidase that leads to production of a dark pigment, melanin. Wound a caterpillar and the hemolymph cells (insect blood) will plug the hole and produce melanin. The caterpillar will have a black spot at the site of the wound. Phenol oxidase reactions are found in most plants and animals. Although the name may be unfamiliar, we are familiar with the phenomena. Phenol oxidase reactions produce the brown color of tea and coffee. Phenol oxidase reactions produce the defensive “ink” of an octopus.

Phenol oxidase has an important role in insect defense against pathogens. At the site of a wound, phenol oxidase will generate reactive chemicals. These chemicals react with the cells of bacteria and other pathogens present at the wound site. Some of the insect cells at the wound site are affected as well. Once released, the reactive chemicals that do not react with cell components, will polymerize to form melanin. Melanin at the site of an insect wound is evidence of the pathogen fighting process.

Circle: Melanin at the site of a Hornworm Caterpillar Wound

Insects are increasingly popular pets in the US. Insects can be comfortable in a small terrarium, they are inexpensive to feed and do not usually run up large veterinary bills. Terrariums can be maintained with a variety of plants planted in a soil or they can be lined with other bedding material.

For many arthropods, especially those requiring a moist environment, coconut fiber (the shredded hulls of coconuts) is a useful substrate for the terrarium. The coconut fiber is relatively inert, does not produce toxic volatiles and retains water. The humidity and moisture can be adjusted watering the coconut fiber. The fiber is resistant to fungus and mold. We recently switched a colony of Madagascar Hissing Cockroaches to a coconut fiber bedding and saw increase in reproduction and colony vigor. The coconut fiber is slightly more expensive than other bedding but it can last a long time and won’t break the bank.

Other bedding products are available for pets including a variety of wood chips. Insect pet owners should be aware that some wood chips and other bedding products (especially cedar chips) have insecticidal or miticidal properties. The cedar chips are inappropriate for most arthropods because volatiles in cedar chips are insecticidal and miticidal. For mammals and reptiles, some insect and mite control can be useful. However, there are some concerns about the wood chips (especially cedar chips) and physiological and allergenic effects of the volatiles on pets and their owners. Reports of allergy to chips are rare and mostly confined to woodworkers with high exposure. More common are allergies to fungus or molds that can grow on chips that are too moist.

Insects may do poorly in a colony exposed to wood chips or wood chip odors. Some types of wood chips are better for insect colonies than others. There are not many controlled studies of bedding materials. Typically, people interested in insect rearing will find a solution that works and move on to other questions. For those with insect pets, what do you use for bedding and how well does it work for you? Consider this an open discussion.

Contented Cockroaches on Coconut Fiber Bedding

Although many red, black-spotted insects are called ladybugs, the term is not accurate.  In fact, these little creatures are not “true bugs” at all but are beetles of the order Coleoptera.   Insects often called “ladybugs” in Indiana are the Asian Lady Beetles that are commonly orange rather than the bright red typically associated with other ladybugs. Lady Beetles are carnivorous and prey on aphids and other small insects.   

The event that brought Asian Lady Beetles to my attention, i.e. the entrance of one into our dorm room, was an exhibition of a behavior characteristic of these particular beetles.  Asian Lady Beetles, unlike other lady beetle species, will invade human structures to hibernate for the winter. Although I am perfectly content to release a wayward beetle back to the outdoors, the appearance of 20 or more insects in my home would be a cause for alarm. 

Getting rid of these insects once they have invaded your home is no small task.  Some recommendations, such as sealing cracks and crevices in your house seem like a no brainer and keep the lady beetles from entering the house.   Others such as vacuuming them, something I distinctly remember my mother doing, will help reduce the problem but may not be infallible.  Lady beetles are known to crawl out of the vacuum cleaner and back into the house when the vacuum is turned off. It seems unfair to destroy the insect, considering it is relatively peaceful toward humans.

Lady Beetles Feeding on Tree Sap

Many parts of the world have fireflies that flash in rhythm. In parts of Southeast Asia, long stretches of river banks are filled with fireflies flashing on and off in unison. Why do fireflies flash in unison and how do fireflies manage to get in sync?

The fireflies that flash in unison are males. By flashing in synchrony, the males are more noticeable to the females and have a better chance of finding a mate. Synchronous fireflies direct attention much better than asynchronous flashes spread over the landscape.

How do the fireflies time their flashes? Synchronous fireflies have an internal clock that causes them to flash at a consistent interval. A solitary firefly will maintain a steady rhythm. If two flashing fireflies are placed together each has its own clock, but how can the clocks be synchronized? Fireflies can detect the flashes of neighboring males. The flash of a neighbor will cause a firefly’s clock to reset. Since individuals have the same clock that produces the same pattern, both the firefly that flashed first and the firefly that just had its clock reset will flash in synchrony on the next interval.

Synchronous fireflies, Photinus carolinus, were first reported in the Smoky Mountains of North America near Elkmont, TN in 1995. The phenomena (like everything else near Gatlinburg, TN) has grown into a popular tourist attraction. For 2 weeks in June, thousands of tourists wait in line to board shuttle busses to see the spectacle.