Sunday, October 3, 2010

Wild and Wooly

I am constantly amazed as I continue to make discoveries in the insect world.  I've named this blog "Wild and Wooly" to simply show a few interesting members of the insect community that have beautiful furry textures and also offer a few interesting facts about them.

Virginian Tiger Moth

 Moths and butterflies share the insect order, Lepidoptera, which is Greek for "scale wing".  They also share a few similar characteristics, but they are classified under different sub-orders and have several morphological differences...way too complex to go into here, so I will just stick with easy, interesting information and observations.

I think the furry appearance of butterflies and moths really add to their appeal, although this feature is sometimes not noticeable at first glance.  This very pretty Virginian Tiger Moth appears to have a beautiful white fur coat wrapped around his body. (I think he looks like a mighty snow king that reigns over a tiny winter fantasyland! OK, enough of my child-like imagination.) The "fur" on moths and butterflies isn't actually fur, but "hair-like" scales that serve several purposes. Since butterflies and moths are ectothermic (meaning they are unable to maintain a constant body temperature without an outside source, such as the sun), the hair on their bodies serve as an insulator to help keep their core temperatures at a functioning level once the air begins to get cooler. They must have a certain body temperature to be able to fly. This is especially important for moths, since they are mostly active at night and cannot rely on basking in the sun as butterflies do.

Since most moths are nocturnal by nature, the hair also serves as protection from bat predators by  absorbing the echolocation calls that bats emit. The fur can absorb so much of the echolocation signals that a bat may not even realize the moth is there. Speaking of bats...Another extremely interesting note regarding defensive mechanisms for moths: Tiger moths can emit ultrasonic "clicks" at a much faster succession than the echolocation clicks of bats, thereby "jamming" the calls of the bat pursuers. This results in the inability of the bat to accurately locate the exact position of the moth. This has actually been proven in scientific studies. It is unbelievable how these tiny, fragile insects have such powerful defensive tactics that go completely unnoticed by the human species!

Since I actually disturbed this Virginian Tiger Moth from his daytime resting period (he had been hiding under some brush that I had cut the previous day and flew out when I cleaned it up), he maintained a stiff posture while I was trying to photograph him. I don't know if he was playing dead or if he was actually in a state of "sleep" because he is not normally active in the day, but he would not move at all. I wanted to get a better picture of his face and eyes, but he kept the eyes obscured with his "labial palps", as you can see in the pictures. These are not legs, but actually mouthparts that are covered with tiny sensory hairs and scales. The moth uses these labial palps to keep the proboscis and eyes clean, and also uses them to assist in determining if something is a viable food source. 

I plucked the blade of grass the moth was holding onto and placed it on a flower, but he still would not move. I took one more picture of this beauty and then left him alone. I don't ever want to cause stress or harm to the creatures I'm photographing. When I returned a few minutes later he had flown off to a private, darker area no doubt to continue resting until his normal activity time, which would begin sometime soon after nightfall.

Miscellaneous butterflies
As a rule, moths are normally more plump and hairy than butterflies. In most cases, that is true, but I've included a few butterflies that I've encountered that do have lots of soft hair on their bodies. You may not notice this kind of detail because of their constant fluttering and busy activity, but as I've noticed with all insects, once you get a close look you notice all kinds of remarkable characteristics. Butterflies definitely adorn our world with beauty and grace, but just what is the purpose of the gorgeous fur on their bodies?

Butterflies warm their bodies by the sun, but like moths, they cannot maintain that body temperature when the fahrenheit dips down. This covering of hair (not really hair, but long hair-like scales) serves as thermal insulation as it does in moths. It also aids in protecting their soft bodies and adds water resistance, but there are also other specialized hairs and scales covering the entire bodies of butterflies (and moths) called "tactile setae" that serve a further purpose. Depending on the species, these tiny hairs may be on the eyes, antennas, body, wings, and legs and each are attached to special nerve cells, which relay information about the hair movement to the butterfly-this is very important for survival. The sensations the butterfly feels provides important feedback as to what is happening to him or to his immediate environment. You can see the many fine hairs and "fur" on this Least Skipper. It even appears that he has long eyelashes! These hairs serve a much higher purpose than just making him look adorable!
The tactile setae also serve a vital purpose for flight on butterflies and moths. The extremely specialized communication between setae and sensory nerves help the adult to sense wind, gravity, and the position of the head, body, wings, legs, antennae and other body parts. The fine hairs on the antennae sense both touch and smell. Butterflies' wings are covered by thousands of overlapping scales, which further strengthen, protect and insulate. They also aid in the flow of air along their wings as they fly. Delicate hairs that form fringed margins along the wings, as pictured below on this Pearl Crescent Butterfly, also provide important aerodynamic functions. 

Here is dorsal view of another tiny, Pearl Crescent Butterfly, showing lots of fine soft hairs. Another purpose for body hair is that of involuntary pollen transfer. As butterflies light from flower to flower inserting their proboscis into flowers, pollen will stick to the hairs on the legs, underside of the body, and even to the proboscis, and they will carry that pollen on to the next flower. Bees are true pollinators, but the butterflies do a fairly good job unintentionally!

Below is a picture of the beautiful Orange Sulphur Butterfly. As you can see, the sulphurs are also very hairy! These butterflies are relatively small, and while in flight their beauty cannot be truly appreciated! Patience and a macro lens help to capture the real beauty and innocence of nature that unfortunately often goes unnoticed!

The picture below is of a Common Wood Nymph. This beautiful brown butterfly has distinctive eye spots on their wings, which function as a special form of defense. If threatened, the wood nymph spreads its wings, displaying the eyespots, which often will distract a predator or possibly even scare it off! The occurrence of patterns and colorations are important survival strategies, (for example, mimicry and camouflage), and also necessary to attract potential mates.  The variation of the pigmentation of scales and how they are positioned and shaped can create beautiful illusions of iridescence and make the butterfly appear to have many more colors than they actually do. Beautifully colored scales also serve to attract a potential mate.

Actually, the properties of the scales on the wings and how they function is very highly complex. Scientists have even taken inspiration from the tiny crevices of butterfly wings to create a nanosensor technology that could detect weapons and explosives, due to the fact that their wings have acute chemical-recognition abilities. It is utterly amazing that such seemingly simple creatures of nature that we take for granted could have such an influence on modern technology!

This wood nymph is found in grassy areas, mostly in fields, open meadows and marshlands. I found a bunch of these in a beautiful open meadow while camping in West Virginia. Every morning they were in the same place under an old apple tree along the corner of an old wooden fence. I felt like they were much more tolerant of my presence than some of the other butterflies, and I truly enjoyed standing still and having them flutter and land all around me!

The Wooly Alder Aphid 
While walking along the shallow end of Lake Logan the other day, something caught my eye. At first glance it appeared that that there was a white fungus growing on a speckled alder sapling along the lake's edge. A closer inspection revealed an amazingly organized colony of hundreds of aphids with white fuzzy bodies packed shoulder to shoulder on a section of the alder.  (By the way, aphids are soft-bodied, tiny insects that suck the sap out of small tree branches, vines, flowers and plants of all kinds.) There are hundreds of different species, but I'll concentrate on the wooly alder aphid. Get ready for an interesting story!

The name, wooly alder aphid, is due to the aphid's ability to secrete a white, waxy filament from their abdomens that resembles white wool. Their bodies become completely covered with these entangled filaments, which serves as a protective defense from predators. Should a predator attempt to eat one of these plump juicy insects, they may just get a mouthful of waxy, wooly fuzz instead of a juicy meal, thus discouraging the attack!

Lets take this wild story from the beginning...The life cycle of this interesting aphid actually starts from the single egg that each female will lay in the bark of a silver maple tree. Once the eggs hatch in the spring the nymphs begin feeding on the mid-vein of new leaves of the maple. Amazingly, ALL young aphids nymphs are wingless FEMALES and they mature quickly and continually give live birth to MORE FEMALE aphids. The act of reproducing young that requires NO MALE INTERVENTION is called parthenogenetic reproduction. This FEMALE-ONLY colony builds very quickly and all remain relatively hidden underneath their own waxy strands.

In late June, they become winged and begin to fly to alder trees to carry on their life cycle on this second host. They resemble little tufts of cotton flying through the air. They continue to reproduce MORE FEMALES and produce more waxy filaments until the occupied areas of the alder begin to look cotton-covered. The population grows rapidly. All summer long they feed on sap and produce female clones.

When fall approaches. something incredible happens...hormones in their bodies change in response to temperature, day length, overcrowding, and quality of food, which suddenly causes WINGED MALES to be produced! The winged males and winged females then fly back to the silver maple trees where they  mate sexually this time and lay eggs, which will overwinter within the cracks and crevices of the bark. New generations will begin in the spring with the hatching of once again ALL-FEMALE wingless aphids (who will quickly become cotton-covered) and new large colonies will accumulate in the maples and then move on to the alders by June's end. (No real harm is caused to either the alder trees or the silver maple trees during the life cycle of this aphid.)

Interestingly, since the parthenogenetic nymphs are actually perfect clones of their parents, they are perfectly adapted to their environment from birth. The occasional mating ensures genetic diversity, which simply means chances for future survival of the species is increased because it allows the species to adapt to a new environment, should there be a change in their current situation.

The picture below shows a couple of ants crawling among the aphids. (There were many ants present, just not pictured). These ants actually protect and "farm" the aphids. They stroke the aphids with their antennas, which causes the aphid to release a drop of a substance rich in sugar that is produced from the sap they suck out of the tree. The ants highly desire this excrement, which is called "honeydew". They will fiercely protect the aphids in return for this honeydew-an example of one of the many mutualistic symbiotic relationships that occur in nature!

Another twist to the amazing life of the wooly aphid is that some insect predators will actually pull some of the wool off of the aphids and attach it to their own bodies to "fool" the ants so they can feed on the aphids without the awareness of the protector ants!!

Flower Scarab Beetle (euphoria sepulcralis)

Scarab beetles are very interesting creatures, with about 30,000 species worldwide. This particular one is a flower-loving scarab commonly named, the "Flower Scarab Beetle." This species is dark brown to black with metallic bronze and green reflections. (The iridescence of this one  actually caught my attention). Although some scarab beetles eat animal dung, the diet of the flower scarab consists of flower pollen, flower nectars and liquids from decaying fruits.  As you can see, this species is somewhat furry, giving them a "teddy bear" appearance!  This is the first time I've ever seen one and I was impressed at how darn cute it was! This one stood on the edge of a Queen Anne's Lace bloom and seemed to lean forward and look right at me! I think he sort of looks like a miniature moose! This is one of the more interesting insects I've had the opportunity to observe.

The ends of a scarab's antennas are made from 3 flattened plates called lamellae that can be compressed into a ball or fan out (as pictured above). When fanned out, this flower scarab is "smelling" the air. Antennas of insects are the primary olfactory sensors. They contain super-sensitive receptors that can also sense vibrations, assess temperature and humidity, and assist in locating food and mates. The scarab will flatten the lamellae when they're not needing to assess their environment (as pictured in the photo below).

Although very sluggish, the beetle still seemed to be quite coordinated as it slowly crawled along the delicate bloom, sometimes hanging upside-down by a leg or two. (Their strong legs are more adapted for digging than for precision climbing). I was careful not to intrude too closely, for if they feel threatened they will feign death and drop off the flower. He didn't seem to mind my curiousness though. I eventually saw a beautiful assassin bug nymph (that I will post in a future blog) that caught my attention and when I looked back, the scarab beetle had flown away to another bloom and I couldn't find him again.

This is not the best angle, but I read that while the scarab's head is buried into a flower, the rear, exposed part resembles a bee due to the coloration and markings, which could serve as a deterrent for a predator.

An interesting note...Scarabs (some extremely beautiful, shiny and colorful) have existed for millions of years, and the Egyptians regarded them as sacred. They were a symbol of resurrection and new life, and they used them for jewelry, amulets and seals for both the living and the dead.