Showing posts with label Bugs and Butterflys. Show all posts
Showing posts with label Bugs and Butterflys. Show all posts

Wednesday, August 10, 2011

UPDATE Sounds of Summer: Part 2 - The Cicada Killer

Shortly after publishing our last 'Bugs of Summer' post on the Cicada Killer Wasp, we spotted one outside of the office dragging her prey. Here she is clutching the Cicada as she crawls along the ground.


She crawled onto the porch and began to climb a post.


For some reason I was unable to rotate this photo, but at this point she is climbing UP the post. You can clearly see the Cicada she is holding and how quickly she is moving her wings in order to support the large bug. Once she got about 4' high she had attained enough altitude to get lift when she turned and flew away!


I promise now, for those of you who have been feeling squeamish about all these insects we have been profiling, to get off of summer break and get back to posting about design topics. At least you can say that you kept up with your biology lessons over the summer vacation - now back to art and horticulture!

Thursday, August 4, 2011

Sounds of Summer: Part 2 - The Cicada Killer

At the end of our last post I mentioned the Cicada Killer, a large predatory wasp. In the interest of giving both 'pest' and prey their due, here is some info on this BIG (but harmless) bug.

The cicada killer wasps attract attention due to their large size, the burrows that they dig in home lawns, and their buzzing flights over the lawn. These insects occur in all states east of the Rocky Mountains and prefer to dig their burrows in sandy, bare, well drained soil exposed to full sunlight. The wasps feed on flower nectar while the immature or larval stage feeds primarily upon cicadas that are brought to the burrow by the adult.



In spite of their large size, the wasps usually ignore people but they can give a painful sting if bothered. Mating males are aggressive and more easily disturbed. A mound of fine soil surrounds the burrow of each cicada killer. Since colonies of burrows are common, infested lawns usually contain several mounds that can smother the grass. However, they prefer to nest in areas of sparse vegetation, and rarely infest thick,vigorous turf.

Cicada killers over winter as larvae in the soil. Pupation occurs in the spring and the adult emerges in mid-June to early July. Emergence continues throughout the summer. Females feed, mate, and dig burrows for several weeks before preying on cicadas. Excess soil thrown out of the burrow forms a regular, U-shaped mound at the entrance.

The females search tree trunks and lower limbs for cicadas. The wasp stings its prey, turns the victim on its back, straddles It, and drags it or glides with it to the burrow. Each cell is furnished with at least one cicada (sometimes two or three) and a single egg before being sealed off. Two to 3 days later the egg hatches. Depending on the number of cicadas in its cell, the larva feeds for 4 to 10 days until only the cicada's outer shell remains. During the fall, the larva spins a silken case, shrinks, and prepares to overwinter. Only one generation occurs each year.

(Information courtesy of The University of Kentucky, image from Purdue University)

Tuesday, August 2, 2011

The Sounds of Summer: Part 1 - Cicadas

Have you been experiencing ringing in your ears? Don't worry - this time of year it's probably just the song of the Dog Day Cicada. We continue our Bugs of Summer Blog Series with a post featuring this summer time singer. What's all the noise about? Turns out that much like the rest of us, this ugly bug is just looking for love!
  

by W.S. Cranshaw and B. Kondratieff
Cicadas are probably best known for their buzzing and clicking noises, which can be amplified by multitudes of insects into an overpowering hum. Male cicadas "sing" to attract females. Many produce loud, shrill buzzing noises with vibrating membranes on their abdomens. The sounds vary widely and some species are more musical than others. Though cicada noises may sound alike to humans, the insects use different calls to express alarm or attract mates.
Cicadas are the large insects in the order Homoptera, which includes other sap-sucking groups such as leafhoppers, aphids and spittlebugs. Although abundant, cicadas are far more often heard than seen. Males make a variety of sounds to attract females. Most commonly heard are loud, often shrill, buzzing, sometimes with several individual insects synchronizing their songs. Other cicadas make clicking noises.


Despite their large size, cicadas cause little injury. The immature stages (nymphs) develop slowly underground. They feed on roots but cause no detectable harm to the plants. The greatest injury occurs when large numbers of certain cicadas insert eggs into stems of trees and shrubs. This egg laying injury can cause some twig dieback.


Cicadas are sometimes mistakenly called locusts, a term properly used to describe certain migratory grasshoppers. This error originated when early European settlers encountered large instances of periodical cicadas in the Northeast. As they had not previously seen cicada outbreaks, they likened them to the locusts described in the Bible.

Life History and Habits

Cicada nymphs develop underground, feeding on root sap of various trees and shrubs. The nymphs are generally pale brown, rather hunch-backed, and have stout forelegs they use to dig through soil. Development likely takes between two to five years to complete. Periodical cicadas, Magicicada species, such as the 17-year and 13-year "locusts," are the longest-lived cicadas. They emerge during synchronized periods, often in spectacular numbers, every 17th or 13th year, respectively.




When full-grown, nymphs emerge from the soil. They crawl up a nearby plant or wall, and the nymphal skin splits along the back. The adults pull themselves from the old skin and hang from the plant for several hours, pumping blood to extend the wings. The new exoskeleton hardens and darkens rapidly and the insects then fly away, leaving behind their cast nymphal skins.


Male cicadas attract females by their characteristic songs. Most cicadas have a pair of tymbals or domed, drum-like organs on the sides of the abdomen. They alternately contract and release muscles to make the tymbals resonate. A large air sac in the abdomen with a thin exterior eardrum acts as an echo chamber that greatly amplifies the sound.


The dog day cicada emerges each year in mid-summer. Adults are present for about four to six weeks following emergence. After mating, the adult females begin to lay eggs in slits in the twigs of various hosts. Upon hatching, nymphs drop to the ground, burrow beneath the soil surface, and spend the next two to five years feeding on plant roots. The insect's amazing lifestyle has been a source of fascination since ancient times. Several cultures, such as the ancient Chinese, regarded these insects as powerful symbols of rebirth.

Natural Enemies of Cicadas

Cicadas have several natural enemies, many with unusual habits. Perhaps most spectacular are the cicada killer wasps (Sphecious speciosus) that look like huge yellowjackets and attack the large dog-day cicadas. Other hunting wasps attack smaller cicadas, using paralyzed cicadas to provision nests dug in soil.


(Information from the Colorado State University Cooperative Extension)


Stay tuned for Part 2 - The Cicada Killer.

Saturday, July 30, 2011

Lighting up the Summer Nights: Part 3 - How to Catch Fireflies




How to catch fireflies

Most of us have fond memories of catching fireflies or lightning bugs on warm summer nights. Many people kept them in jars—sometimes a jar full of fireflies can produce enough light to read by. If you want to catch fireflies, here are a few tips that will help you along.

Where to Look - Fireflies are easy to spot—just look for the flashing lights. They typically love long grasses, marshy areas and regions near the edges of ponds, lakes, streams and other bodies of water. They can thrive under low-hanging trees, in forests and fields, and even in your yard or vegetable garden.

Watch Your Light - Fireflies communicate using their flashing lights. If you want to catch one, you have to act like one. First, turn off your exterior house lights—these may confuse fireflies and make them less likely to respond to light signals from other fireflies. Then take a flashlight outside. If you are having trouble getting near the fireflies in your yard, imitate one of them by shining your flashlight directly up and down, or by repeating the light patterns you see fireflies emitting. This may or may not work; many scientists who study fireflies have better luck with LED lights than with battery-powered flashlights. Never shine a light directly at a firefly; it’s likely to scare them away rather than attracting them. In addition, you may have better luck catching fireflies if you place a blue plastic disc or piece of paper over your flashlight to turn the light blue. Scientists believe fireflies don’t interpret blue light the same way they see other colors, so the light won’t disorient their flash patterns.

Catch Carefully - When you get close enough, catch your fireflies using a net. Place the fireflies you catch into a clear jar with a lid that’s been pierced to let in air. You should also place a moistened paper towel inside to keep the air in the jar humid. This way, your fireflies will have air to breathe and won’t dry out.
It’s often more effective to work in pairs when catching fireflies, with one person to hold the jar and another to use the net. Be sure to use care when catching them; fireflies can be fragile.

Let Them Go - Once you have a jar of fireflies, don’t keep them for longer than a day or two. Let them go, preferably at night because that’s when they’re most active and able to avoid predators. If you keep them for longer, the fireflies are likely to die.
Some people remember crushing fireflies in their fingers to make their hands glow and keeping them in unventilated jars for several days. While this might not have caused serious damage to firefly populations in times when they were more plentiful, today’s firefly numbers are dwindling—so each one matters. Catch fireflies carefully, treat them gently and release them into the wild again when you’re done, and you’ll be able to enjoy these fascinating creatures without causing any harm.

(Information gathered from www.firefly.org)

Thursday, July 28, 2011

Lighting up the Summer Nights: Part 2 - Attracting Fireflies



How to attract fireflies:

Fireflies live in various habitats, thriving in forests, fields and marshes near lakes, rivers, ponds, streams and vernal pools. Fireflies also love long grass. They’re nocturnal, and during the day they spend most of their time on the ground. At night, they crawl to the tops of blades of grass and fly into tree branches to signal for mates. Long grass conceals the fireflies better and allows them a better vantage point for signaling at night, and over-mowing your lawn may disturb your firefly population.
Fireflies are disappearing all over the world, and it’s believed to be because of human encroachment on habitat and increased light pollution from development and traffic. But there are a few things you can do to help fireflies make a comeback in your area.
None of these steps have been proven to work, mainly because scientists have only been studying firefly populations for a few years and data is still inconclusive. But signs point to human development, light pollution and toxic chemicals as likely culprits behind the dwindling of firefly populations. Follow these steps, and with luck your yard will once again sparkle on summer nights.

Turn off outside lights at night - Fireflies use their flashing lights to signal each other, attract mates and warn of danger. While the science is still preliminary, it’s likely that human light pollution can disrupt their flashes—making it harder for fireflies to find mates and breed. This leads to fewer fireflies mating and smaller numbers in subsequent generations. You can make your yard a haven for fireflies by turning off exterior and garden lights, and drawing your blinds at night so that interior light doesn’t brighten your yard too much.

Let logs and litter accumulate - Some species of firefly larvae grow up in rotten logs and the litter that accumulates beneath the forest canopy. To encourage their growth, plant some trees on your property. If you have trees in your yard, consider leaving some natural litter around them to give firefly larvae a place to grow.

Create water features in your landscape - Most species of fireflies have one thing in common: they thrive around standing water and marshy areas. Ponds, streams and rivers can all provide good habitats for fireflies, but even a small depression full of water can cause them to congregate. Build a small pond or divert a small stream to run through your property, and it’s more likely you’ll see fireflies at night. Chemically treated swimming pools aren’t a good substitute; fireflies are believed to eat the smaller insects, grubs and snails that thrive in natural ponds and streams, and these don’t live in chlorinated environments.

Avoid use of pesticides - It’s likely that chemical pesticides and weed killers may also have a negative effect on firefly populations. Fireflies and their larvae may come into contact with other insects that have been poisoned, or they may ingest the poisons from plants that have been sprayed. Avoid using pesticides on your lawn and you may boost firefly populations.
A notable example of how overspraying has affected a local population is the extinction of the dusky seaside sparrow who was native to the salt marshes of Merritt Island in Florida. Its habitat was sprayed with DDT to control mosquitoes and human development quickly changed the ecosystem so much that the bird could not compensate and went extinct.
Many communities over spray for mosquitoes at night just when fireflies are active, flashing and mating. Such over spraying can wipe out firefly populations. These same communities often do not implement more effective control of mosquitoes, such as neighborhood programs to reduce standing water, especially in swimming pools, and usage of mosquito larvacides to prevent the growth and development of mosquitoes in drainage ditches. By encouraging broad spectrum mosquito control efforts and discouraging spraying at times when fireflies are active, communities can actually save money and effect better control of mosquitoes, causing less impact to firefly species and other small animals.

Use natural fertilizers - While no conclusive studies have been done, it’s possible that chemical fertilizers may have a harmful effect on firefly populations as well—especially since many harmful chemicals in pesticides are also found in chemical fertilizers. Using natural fertilizers may make your yard a more healthy place for fireflies.

Don’t over-mow your lawn - Fireflies mainly stay on the ground during the day, and frequent mowing may disturb local firefly populations. While you may feel that you need to keep your lawn mowed for aesthetic purposes, consider incorporating some areas of long grasses into your landscaping. Fireflies prefer to live in long grasses, and doing this may boost their population in your yard.

Plant trees - Fast growing pine and native trees provide a good habitat for many species of fireflies. Naturalist Terry Lynch, who has studied fireflies for many years, recommends Pine trees because they provide shade and the low light area provided by a canopy actually increasing the amount of time fireflies have to find a mate. Also, the litter produced by pine trees, if left to accumulate, provides a good habitat for earthworms and other small animals which firefly larvae feed upon.

Introduce earthworms - Firefly larvae can hunt earthworms which they will attack, paralyze and devour alive! Introducing earthworms to your lawn and garden will provide a great source of food to encourage fireflies; plus, earthworms help break up soil and break down vegetation to provide natural fertilizer for your lawn and garden. Earthworms may be ordered in bulk on-line from suppliers or purchased from bait shops.

Talk to your neighbors - If you live in a suburban area in close proximity to others, what you do in your own yard will help—but you can create even more habitat for fireflies by enlisting your neighbors in your efforts. Tell your neighbors about your concern over dwindling firefly populations and what they can do to help. If you convince even one or two people on your street, you could help increase firefly habitat in your area even more.

Fireflies are disappearing all over the world. But there are a few things you could do to help—and every little bit counts. Allow some room for wildness on your property—low-hanging trees, forest litter, and long grasses all create welcoming environments for fireflies. Ponds and streams are crucial to firefly populations, and you can further encourage their numbers by reducing the amount of light in your yard at night and by cutting back on chemical fertilizers and pesticides. Follow these tips, and it’s possible you could see a resurgence of fireflies in your area.

(Information gathered from www.firefly.org)      Stay tuned for Part 3 - How to Catch Fireflies   

Monday, July 25, 2011

Lighting up the Summer Nights: Part 1 - Firefly Facts


Firefly Facts:

Fireflies talk to each other with light - Fireflies emit light mostly to attract mates, although they also communicate for other reasons as well, such as to defend territory and warn predators away. In some firefly species, only one sex lights up. In most, however, both sexes glow; often the male will fly, while females will wait in trees, shrubs and grasses to spot an attractive male. If she finds one, she’ll signal it with a flash of her own.

Fireflies produce “cold light” - Firefly lights are the most efficient lights in the world—100% of the energy is emitted as light. Compare that to an incandescent bulb, which emits 10% of its energy as light and the rest as heat, or a fluorescent bulb, which emits 90% of its energy as light. Because it produces no heat, scientists refer to firefly lights as “cold lights.” In a firefly’s tail, you’ll find two chemicals: luciferase and luciferin. Luciferin is heat resistant, and it glows under the right conditions. Luciferase is an enzyme that triggers light emission. ATP, a chemical within the firefly’s body, converts to energy and initiates the glow. All living things, not just fireflies, contain ATP.

Firefly eggs glow - Adult fireflies aren’t the only ones that glow. In some species, the larvae and even the eggs emit light. Firefly eggs have been observed to flash in response to stimulus such as gentle tapping or vibrations.

Fireflies eat other fireflies - Fireflies are primarily carnivorous. Larvae usually eat snails and worms. Some species of fireflies feed on other fireflies—most notable is the genus photuris, which mimics female flashes of photinus, a closely related species, in order to attract and devour the males of that species. But adult fireflies have almost never been seen feeding on other species of bugs. Scientists aren’t sure what they eat. They may feed on plant pollen and nectar, or they may eat nothing.

Fireflies have short lifespans - An adult firefly lives only long enough to mate and lay eggs—so they may not need to eat during their adult life stage. The larvae usually live for approximately one year, from mating season to mating season, before becoming adults and giving birth to the next generation.

Fireflies imitate each other - Female photuris aren’t the only impostors among fireflies—the species is surprisingly devious when it comes to imitation. Sometimes male photuris imitate male photinus to attract females of their own species. She shows up looking for food, but instead he gets a mate. Even more interesting, scientists believe some photinus males imitate photuris females giving off bad impressions of photinus male flashes, scaring off other photinus males and reducing competition.

Fireflies are medically and scientifically useful - The two chemicals found in a firefly’s tail, luciferase and luciferin, light up in the presence of ATP. Every animal has ATP in its cells in amounts that are more or less constant—or should be. In diseased cells, the amount of ATP may be abnormal. If the chemicals from fireflies are injected into diseased cells, they can detect changes in cells that can be used to study many diseases, from cancer to muscular dystrophy. But that’s not all they’re used for. Electronic detectors built with these chemicals have been fitted into spacecraft to detect life in outer space, as well as food spoilage and bacterial contamination on earth.

Fireflies don’t make tasty prey - When attacked, fireflies shed drops of blood in a process known as “reflex bleeding.” The blood contains chemicals that taste bitter and can be poisonous to some animals. Because of this, many animals learn to avoid eating fireflies. Pet owners should never feed fireflies to lizards, snakes and other reptilian pets. Scientists aren’t completely sure what most species of fireflies eat though. It’s probable that firefly larvae feed on different prey from that of adult fireflies. The larvae are believed to be carnivorous, living off smaller insects, snails and slugs. Adult fireflies may also live on other insects, as well as pollen and plants, but it’s possible that some species don’t eat anything—their lifespan is only a few weeks long. But scientists believe fireflies thrive in wet areas because their prey does as well—including other insects and insect larvae, slugs and snails.

Fireflies are found on almost every continent - Fireflies love warm, humid areas. Because of this, they thrive in tropical regions as well as temperate zones—they come out in the summertime in these environments—on all continents except Antarctica. Fireflies live in various habitats, thriving in forests, fields and marshes near lakes, rivers, ponds, streams and vernal pools. They need a moist environment to survive, but they don’t need a lot of water to get by. Vernal pools and small depressions that hold water during firefly mating season can all provide the habitat fireflies need. Most firefly species live at the margins where forest or field meet water. Some species of firefly larvae are generally aquatic—they even have gills—while others live almost entirely in trees. Many species thrive in forests, fields or the margins between them. Some live in more arid areas, but they typically follow the rainy season. Fireflies are found all over the world, from North and South America to Europe and Asia. In the U.S., almost no species of fireflies are found west of Kansas—although there are also warm and humid areas to the west. Nobody is sure why this is. There are many species of fireflies throughout the world, and the most diversity in species is found in tropical Asia as well as Central and South America.

(Information gathered from www.firefly.org)      Stay tuned for Part 2 - Attracting Fireflies    


Thursday, July 21, 2011

Humming Along through Summer - Part 3: The Beneficial Braconid Wasp

In our recent post on Hummingbrid Moths, I  mentioned the interesting life cycle of the the parasitic wasp affecting the moths hormworm caterpillar larvae. Here are some more details I have gathered on that beneficial little insect: 

Common names:  Braconid Wasp
Scientific name:  Braconidae
Region:  This particular wasp has many species that exist throughout North America and Europe.
Physical Description: Harmless to humans and animals.  Species can vary in color from yellowish, black, or red and are usually 1/10 to 1/4 inches long.  The eggs are laid in the bodies of host insects, where the white worm-like larva develops.
Feeding characteristics: The Braconid is among the most important of the aphid parasites, as well as, the larvae of butterflies, Sawflies, moths and many beetles.  If you see any hornworms or caterpillars with cocoons covering it, don't remove it from your garden, it has been parasitized.  This wasp will attack various caterpillars or aphids.  The adults feed on the nectar from the flowers of weeds and flowers of the daisy (Chrysanthemum) and carrot (Umbellifers) families.

Notice the long 'tail' on this wasp. It is not a stinger, but the ovipositor which the female wasp uses to lay her eggs.
Meet the Braconidae, a wasp family that is a friend to the home gardener and commercial producer alike. Belonging to Hymenoptera, the same order as ants, bees and other wasps, these little jewels are a significant biological control against thousands of other insect species, including many that are considered pests.

Although highly variable in appearance, they are usually dark with four transparent wings and rarely over one-half inch long. Their size and the fact that there are over 15,000 described species make them difficult to notice, much less identify.

The quality that makes this insect family worth noticing is that most of them are parasitoids: parasites which usually kill their hosts. And, they like to feed on things we don’t like in our gardens: hornworms, caterpillars, beetles, aphids, squash bugs and stink bugs are among the many pests that members of the Braconidae family consider gourmet delicacies.

Here is a Tomato Hornworm caterpillar victimized by the rice-like eggs of the  wasp larvae.
Different species attack their insect hosts during different stages of development, as eggs, larvae, pupae, or adults. They may become internal or external parasites. Braconid females can use the ovipositor, the tube through which eggs are laid, to sting. They generally don’t unless trapped or mishandled. The sting is considered medically harmless.

Individual species tend to be specialized to a particular host. A good example is the Cotesia congregatus (older name, Apanteles congregatus). Less than 1/8 inch long, black with yellowish legs and clear wings, this tiny wasp considers the tobacco hornworm (Manduca sexta) and the tomato hornworm (Manduca quinquemaculata) “meals on wheels.”

The female wasp uses her ovipositor to lay eggs just under the skin of an unlucky hornworm. As the eggs hatch, the larvae feed on the hornworm’s viscera–literally eating a hornworm alive. Larvae chew their way out through the host’s skin when they mature.

Once outside, the future wasps pupate, spinning tiny oval cocoons that look like insect eggs along the external back and sides of the worm. These fellows–and ladies–are not just innocently hitching a ride. When the adult wasps emerge from the cocoons, the already weakened hornworm will soon die, thus preventing any further defoliation on tomato plants.

So, if you see a bright green hornworm carrying what looks like a clutch of white-colored insect eggs on its back, leave it there! The hornworm is not only feeding its own destruction, it is also carrying potential destroyers of hornworm brothers, sisters and descendants. That means we get those wonderful, luscious tomatoes right off the vine, the braconids get a meal and a future, and the hornworms get…GONE! 

(Information courtesy of the Galveston County, TX Master Gardeners website, written by class of 2006 member, Betty Gray)

Monday, July 18, 2011

Humming Along Through Summer - Part 2: Hummingbird Moth

After our last post on humingbirds I photographed this little beauty at our office, it is one of a species of Hummingbird Moths, the Snowberry Clearwing:




The Snowberry Clearwing Moth is a small hummingbird moth which more closely resembles a large bumblebee rather than a hummingbird. Like other hummingbird moths, this one flies during daylight. 

This bumblebee mimic is yellow with black wings and abdomen. At 1.25 to 2 inches, its wingspan is slightly smaller than that of the hummingbird clearwing. Its larvae feed on honeysuckle, dogbane and buckbrush. Adults eat from many flowers, including thistles, milkweed and lilac. A similar, but larger, sphinx moth is the (Hemaris thysbe) Hummingbird Clearwing Moth. 

A close relative, the hummingbird clearwing is common in North America.  Its larvae feed on honeysuckle, buck brush, wild cherry and plum. Adults hover to take nectar at many different flowers, including honeysuckle, bee balm, phlox, lilac and bergamot. 



Adult sphinx moths are medium to large moths with wingspans ranging from about 1.25 inches to 4.75 inches. The snowberry clearwing is one of the smallest moths in this group, while the five-spotted hawk moth is one of the largest. 

Ironically, its larva is the familiar and hideously ugly hornworm, know to destroy tomato plants. It is interestingly often the victim of a tiny beneficial predatory wasp which lays rice-like eggs on the caterpillar for its larva who devour the hornworm from the inside out.





The Carolina sphinx, whose larva is known as the tobacco hornworm, weighs only one to two grams, but it flaps its wings an astonishing 25 to 30 beats per second. Some sphinx moths have been clocked at speeds as high as 30 mph.

Sphinx moths are often mistaken for hummingbirds and bumblebees because of their similarities in size, foraging behavior and feeding structures. Many sphinx moths are nocturnal, but several species are diurnal, meaning they are active during the daytime when hummingbirds and bumblebees are also foraging. Adult sphinx moths have a long, straw-like "tongue," called the proboscis, which they keep curled under the head. They use it to suck nectar from the flower. The nectar is rich in sugar, which fuels the energy required for hovering.


It is not difficult to see why many gardeners would mistake an Hemaris thysbe moth for a small hummingbird as it hovers, sipping nectar from flowers through a long feeding tube. The moth hovers briefly, sipping for only a few seconds before darting off to a new flower. Green body "fur" and burgundy wing scales suggest a small ruby throated hummingbird.

Hummingbirds do not have striped backs. They do not usually appear to be brown. They will not let you approach them to get a closer look. If you believe you saw a brown, striped hummingbird, you probably saw the perfect hummingbird look-a-like. Hummingbird moths have disappointed many people who believed that they were seeing their first hummingbird.

Although you may have to wait a little longer to see a hummingbird, hummingbird moths are very interesting in their own right. Unlike most moths, they will fly during daylight. You can see many of them at any time of day but evening is the most productive time to watch for hummingbird moths.

Moths, including sphinx moths, pollinate many species of plants. Moth-pollinated flowers tend to have a strong, sweet scent and are white or pale in color. Gardens planted with these flowers may attract several kinds of sphinx moths, including the hummingbird and bumblebee mimics. However, since these moths rarely come into contact with flowers except for the tip of a carefully-placed foot, and, of course, their proboscis, they are not important pollinators.

(Information was compiled from several sources found via a Google search of the term 'Hummingbird Moth')