MEET THE FALL CANKERWORM

Posted in Insects, Moths, Pests on January 19, 2011 by Dr. Art Evans

By Arthur V. Evans

Adult male fall cankerworm, Alsophila pometaria. ©2011, A.V. Evans

During a recent warm spell on the heels of New Year’s Day, a small collection of somberly hued moths gathered at my front porch light. I posted a picture of one of these moths on my entomology page on Facebook, and it was immediately identified as the fall cankerworm, Alsophila pometaria (Harris), a moth in the family Geometridae. The caterpillars of geometrids are collectively called inchworms. Adult fall cankerworms present a striking example of sexual dimorphism. Males are fully-winged, while the females are wingless. Native to North America, fall cankerworms are found from Nova Scotia to South Carolina, west to western Alberta, Colorado, Kansas, and California.

Adult female fall cankerworm, Alsophila pometaria. ©2011, A.V. Evans

Adults are typically active in fall and early winter. Females lay batches of 50-200 carefully aligned and upright eggs on small twigs and branches. Before leaving, they cover their eggs with scales from their abdomen. Upon hatching in late spring, each caterpillar descends from its egg on a single silken strand and is dispersed by the wind.

The ravenous larvae consume leaves and young fruits of many kinds of deciduous tree and are especially fond of maple, oak, and elm. Young larvae “skeletonize” patches (cankers) on the undersides of leaves by eating only the leaf tissues between the small veins. Older larvae consume nearly all leaf tissues and leave only the major veins behind. After 4-5 weeks of feeding the caterpillars reach maturity and lower themselves on to the ground via silk strands to enter the soil to pupate.

Fall cankerworm. © 2012, A.V. Evans

Large numbers of fall cankerworm larvae can defoliate trees and seriously damage fruit trees. Most trees and shrubs can withstand the onslaught, but mortality is possible if the plants are already stressed from drought and other adverse conditions. Check with your local nursery or extension agent for information on effective controls for fall cankerworms.

References

Cranshaw, W. 2004. Garden insects of North America. The ultimate guide to backyard bugs. Princeton University Press, Princeton, NJ. 656 pp.

Johnson, W.T. and H.H. Lyon. 1994. Insects that feed on trees and shrubs. Second edition with corrections. Cornell University Press, Ithaca, NY. 560 pp.

Powell, J.A. and P.A. Opler. 2009. Moths of western North America. University of California Press, Berkeley, CA. 369 pp.

© 2011, A.V. Evans

WHAT’S ALL THE BUZZ ABOUT NOBEL PRIZE SEASON?

Posted in Ants, bees, wasps with tags , , , on October 10, 2010 by Dr. Art Evans

By Arthur V. Evans

There have been plenty of reports in the news lately regarding the 2010 Nobel Prizes awarded for cultural and scientific endeavors. The prizes were established in 1895 in the will of the Swedish chemist Alfred Nobel, whose fortune was built on, among other things, the invention of dynamite. First awarded in 1901, the prizes are given annually in recognition of outstanding achievement in the fields of chemistry, literature, medicine, physiology or medicine, and physics. The best known and often controversial prize is the Nobel Peace Prize.

This is a good time to recall that nearly 40 years ago Austrian Karl von Frisch (1886-1982) received the Nobel Prize  in Physiology or Medicine in 1973, along with Nikolaas Tinbergen and Konrad Lorenz, for his pioneering work on communication between insects by studying the sensory perceptions of honey bees that led to the deciphering of their waggle dance in 1946. You can download a copy of von Frisch’s Nobel Lecture here.

Although sometimes claimed by entomologists as one of their own, Von Frisch was actually an ethologist, a zoologist that examines animal behavior relative to their environment. His studies with honey bees (Apis mellifera) produced several revelations. For example, von Frisch discovered that foraging bees were able to discriminate among different species by their scent and that individuals bees consistently forage among the same species of flower. He also learned that, in spite of a great sense of smell, the sense of taste is not particularly well-developed in bees.

He also established that bees can distinguish the colors of  blue, violet, white, and yellow, but that black and red were colorless and therefore indistinguishable to them. Under ultraviolet light, the pigments that make up these colors appear as multicolored patterns called nectar guides.

Von Frisch determined that bees orient themselves and can tell time of day primarily by their relative position to the sun. On overcast days or inside their hives, bees can still do all this by using the polarized light pattern of even a small patch of blue sky, or by relying the Earth’s magnetic field when moving about inside the hive, respectively.

Using all the tools at their disposal, Karl von Frisch proposed that not only do bees have the ability to gather orientation and temporal information from the sun’s daily movement across the sky, they can also relate this information to the current position of the sun from the dark recesses of the hive. This allows foraging bees returning from the field to provide up-to-date information on the direction and distance of nectar sources to their hive mates without having to go back outside to reorient themselves. This information is relayed by performing two basic kinds of “dances.” The information conveyed in these dances is received and interpreted on the vertical surface of the comb and put into practice on a horizontal landscape.

The round dance communicates information about nearby nectar sources about 50-100 meters from the hive. Whirling about in a tight circle, the dancing bee completes two circuits one way, then abruptly turns the other for two more circuits. Delivered on a thickly populated section of comb, bees in the immediate vicinity of the dancing bee struggle to keep their antennae in contact with the dancer’s abdomen. Soon the dancing bee’s wake is filled with bees all fervently trying to keep in step. Direction is not conveyed during the dance, but the type of flowers is transmitted through the dancing bee’s odor.

The waggle dance presents information on distant pollen and nectar sources. The dancing bee moves a specific distance in a straight line on the comb, turns and walks a half circle, then retraces the straight line and waggles its abdomen. Turning in the other direction, the bee completes a figure-8 pattern and waggles along the straight line again. The direction of the straight line relative to the vertical plane of the comb reveals the precise direction of food source relative to the position of the sun. The intensity of the dance, as measured by the number of times the waggle dance is performed informs the other bees as to distance of the food source. Bees receive and reinforce this information by copying the dance and by sensing the odors of dancing bee. Fully informed by the waggle dance, the newly recruited bees leave the hive and locate the food source regardless of intervening physical barriers, natural or man-made.

My first exposure to von Frisch and his groundbreaking work with honey bees was through the 1964 Life magazine article about his life and research at the tender young age of seven. Later in 1966, I saw him in one of the very first National Geographic television specials, The Hidden World of Insects (another milestone in this entomologist’s fascination with insects). I clearly remember being fascinated by his painstaking experiments with experimental feeding stations set among open grassy habitats and stocked with petri dishes of different colors and filled with various sugar solutions.

Karl von Frisch also studied the pheromones produced by queen honey bees and the role they had in maintaining the social order of the colony. Although he published all of his is original findings in German, von Frisch did produce some popular works in English. Two of these titles have long been in my library. Both works are fascinating to read. Animal Architecture covers both vertebrates and invertebrates, including some wonderfully illustrated information on the structures built by arthropods.

Scientists have long been skeptical or flat-out rejected von Frisch’s work with honey bees and his results suggesting that these industrious insects had a language all their own. Recent studies suggest that the importance of the bee’s dance may not be as great as once thought and that most of the bees that witness the dance get it all wrong, if they don’t just ignore it altogether. Only a few workers that “get” the information actually find the food source.

Other scientists are not ready just yet to discount the importance of dancing bees to the overall success of the hive. Both camps agree that most of the research thus far has focused on the message delivered by dancing bees and that there is still much to be learned how this information is perceived by other members of the hive.

WEB SOURCES:

2009. The bees’ knees-The facts. New Internationalist Magazine. http://www.newint.org/features/2009/09/01/facts-about-bees/ (accessed 10 October 2010)

2010. Karl von Frisch. Wikipedia. The Free Encyclopedia.  http://en.wikipedia.org/wiki/Karl_von_Frisch (accessed 10 October 2010)

PRINT SOURCES

von Frisch, K. 1953. The dancing bees. An account of the life and senses of the honey bee. New York: Harcourt, Brace & World Inc. 182 p.

von Frisch, K. 1974. Animal architecture. New York: Harcourt, Brace, Jovanovich. 306 p.

Williams, C. 2009. Show me the honey. New Scientist 203 (2726): 40-41.

REFLECTIONS ON ARIZONA’S JEWEL SCARABS-Part 1

Posted in Arizona, Beetles, Insects with tags , , , , on September 27, 2010 by Dr. Art Evans

By Arthur V. Evans

I can still remember the very first Chrysina that I ever saw alive in Arizona. It was August 5, 1973 and Bob Duff and I had just set up our black lights in Bog Springs Campground in Madera Canyon. A soft-spoken man sporting a white t-shirt, khakis, and a crew cut came into our camp and introduced himself as Gayle Nelson. Only later did I discover that Dr. Nelson was one of the world’s leading authorities of jewel beetles (Buprestidae).

As the sun slowly set, the oaks all around us came alive with the buzzings of beetles. As Bob, Gayle, and I conversed, my eyes darted nervously this way and that  to each and every buzz in the bushes. This was my first night of black lighting in Southeastern Arizona’s Sky Islands and I did not want to miss any choice beetles! I did not know then that most of this crepuscular beetle activity was just the mating and feeding frenzy of several species of plain brown or black June beetles (Phyllophaga).

Just as darkness had completely descended upon us, I heard a bigger buzz followed by a thud. There on the sheet in front of me was an apple green beetle on its back with its lavender legs clawing at the air. I picked up the gorgeous beetle with my thumb and forefinger, only to discover that it’s powerful legs were tipped with needle-sharp claws. In spite of this surprisingly painful encounter, I was not about to let go of my very first Beyer’s jewel scarab, C. beyeri.

For several years afterwards the abundance of Chrysina at my lights were used as a barometer of sorts. I used their numbers, rightly or wrongly, as a way of measuring my success during many summer nights of black lighting in the mountains of Southeastern Arizona. Eventually my sensibilities began to change.

During the 1990’s, I collected specimens of C. beyeri and C. gloriosa alive and took them back to California for display in the Ralph M. Parsons Insect Zoo at the Natural History Museum of Los Angeles County, where I worked as the director. Both species thrived for several months on diets of oak leaves and juniper, respectively. Although the captive scarabs produced plenty of grubs, I made no effort to rear them to adulthood. To this day I regret not writing a formal description of the larva of Beyer’s jewel scarab and submitting it for publication; as of this writing, the immature stages of this species remain undescribed.

Now I regard species of Chrysina at my lights simply as old friends and no longer feel the urge to collect them in long series, if at all. I have heard stories of collectors and dealers with considerably less restraint collecting hundreds of specimens from the same mountain canyons, year after year. This annual carnage has led some people to wonder out loud whether or not Arizona’s Chrysina are in real need of some sort of legal protection. Nearly 30 years ago, Arnett and Jacques (1981) declared that both C. beyeri and C. gloriosa, which they mistakenly thought were the only species in the United States, were “…endangered and should not be collected.” However, on a warm and dry night in Madera Canyon this past July, all three species of Arizona’s Chrysina turned up at my light in good numbers. One species, C. gloriosa, was there in incredible abundance. Still, it would be worthwhile for a university or governmental agency to study the overall impact of intensive collecting on Chrysina populations in Madera Canyon and other popular collecting sites in southeastern Arizona.

Commonly known as jewel scarabs, the genus Chrysina is replete with incredibly beautiful, often metallic species. It includes nearly 100 species, most of which occur in Mexico and Central America. The four species in the United States are relics of a rich Neotropical fauna that expanded northward during more favorable (wetter) periods. For the past 10,000 years or so, these species were able to adapt to an increasingly warmer and drier climate by taking refuge in the high elevations of mountains.

 

Weldon Heald

 

The Southwest mountains inhabited by Chrysina are like stepping stones that bridge the gap between the temperate flora and fauna of the Rocky Mountains of the United States and the tropical biota of the Sierra Madre Occidental of Mexico. This archipelago of mountain “islands” in southeastern Arizona, southwestern New Mexico, and northern Mexico are surrounded by hot, dry desert “seas.” As such, they were dubbed “Sky Islands” nearly 60 years ago by the natural history writer Weldon Heald. Arizona’s Sky Islands are home to three species of Chrysina; the fourth American species is found in Texas.

All four of the American jewel scarabs were originally described in the genus Plusiotis. As a result of morphological and DNA evidence, the newer name Plusiotis was deemed redundant in relation to the older monicker Chrysina and it was formally synonymized by Dave Hawks (2001). The first species known in the United States, the glorious jewel scarab (C. gloriosa), was described by the father of American coleopterology, John L. LeConte in 1854. LeConte described this emerald-green and silver-striped species based on specimens collected at a copper mine in Texas that are now in the Museum of Comparative Zoology (MCZ) at Harvard.  These specimens were collected by the Secretary of the United States and Mexican Boundary Commission, Thomas Hopkins Webb. A physician from Rhode Island, Webb was appointed Secretary of the Commission in 1850, a position he held until 1854. In addition to his full-time position as Secretary, Webb enthusiastically collected insects, fishes, and reptiles and sent them to the leading authorities of the day. Later, he would become the secretary and principal executive officer of the Massachusetts Institute of Technology.

According to my friend, colleague, and Arizona scarabaeologist Bill Warner, C. gloriosa occurs in nearly all of the mountain ranges in at least the southern three-quarters of the state where their food plant, Juniperus, grows. Glorious jewel scarabs also occur in New Mexico, and Texas, as well as the Mexican states of Chihuahua and Sonora. With the onset of the summer monsoons, adults often spend their daylight hours feeding and resting on junipers; they are commonly attracted to lights at night, sometimes in large numbers.

In 1882, two years after LeConte’s death, another prominent coleopterist named George Horn described the second American species of Chrysina, LeConte’s jewel scarab (C. lecontei). His description was based on three examples now housed at the MCZ. These included one specimen from Tucson in the cabinet of England-born actor and entomologist Henry Edwards, another from LeConte’s cabinet collected in New Mexico by the curator of the insect collection at the University of Kansas, Professor Francis H. Snow, and a series in his own collection from Prescott, Arizona. Without any fanfare whatsoever, Horn ended his description by quietly dedicating the new species “to a friend.”

Warner notes that LeConte’s jewel scarab has essentially the same range in Arizona as the glorious jewel scarab, but that it is a bit more restricted to the higher altitudes where its food plant, the ponderosa pine, occurs. This species also occurs in New Mexico and the Mexican states of Chihuahua, Durango, Sinaloa, and Sonora.

 

Henry Skinner

 

The third American species of Chrysina was first exhibited by Horn on November 9, 1883 at a meeting of the entomological section of the Academy of Natural Sciences in Philadelphia. He presented two specimens collected in Rio Grande, Texas by his friend and Philadephia physician, Dr. Horatio C. Wood. Wood was a pioneer in American pharmacology who published numerous papers on pharmacology, physiology, and experimental therapeutics and taught neurology and internal medicine at the University of Pennsylvania. Early in his career Wood published papers in botany, entomology, and myriapodology. He traveled to the borderlands to collect specimens for the Smithsonian Institution and was one of the first white men to see the Grand Canyon. Wood recalled to lepidopterist Dr. Henry Skinner (1905) that the beetles he had given to Horn were either collected near El Paso, Texas, or in the valley of Tornellias [Tornillo] Creek at the great bend of the Rio Grande. The beetles were described in the minutes for the meeting as “pale malachite green, narrowly bordered with pale gold, the elytra are not striate, but with rows of fine punctures, the tarsi are beautifully violet.” Horn formally described Wood’s jewel scarab, Chrysina woodii, in 1885. These specimens are also housed in the MCZ. Horn noted that he saw another specimen in the Museum of the Jardin des Plantes in Paris. Wood’s jewel scarabs eat the leaves of walnut trees and are apparently diurnal, although some individuals are attracted to lights at night. It also occurs in Chihuahua, Mexico.

In 1905, Skinner, a gynecologist as well as co-founder and editor (1890-1910) of the Entomological News, described Beyer’s jewel scarab (C. beyeri) from four specimens collected in Carr and Miller Canyons in the Huachuca Mountains in southeastern Arizona. This handsome species first came to his attention the previous year when a specimen was sent to him from Reef in Cochise County. Reef was a mining camp in the southwest corner of Cochise County near the Mexican border. It was located in Carr Canyon in the Huachuca Mountains and was named for a noted landmark Carr Reef, an exposed and thick layer of rock. The site is now a campground in the Coronado National Forest. Skinner examined additional specimens presumably collected from the same locality by Beyer, Schaeffer, and Biederman. The Reef post office was officially relocated to Palmerlee (at the base of Miller Canyon) in December of 1904.

Gustav Beyer was a fur manufacturer from New York and an indefatigable insect collector who frequently travelled with his friend and Curator of Coleoptera at the Brooklyn Museum Institute of Arts and Sciences, Charles F. A. Schaeffer. Schaeffer spent a considerable amount of time collecting beetles at his three favorite haunts: Mt. Mitchell in North Carolina, the Lower Rio Grande Valley in Texas, and the Huachuca Mountains. Charles R. Biederman, a veteran of the Confederate Army and a resident of the Huachuca Mountains, was an ardent insect collector and is buried on his homestead in Carr Canyon. Before the advent of collecting Chrysina and other nocturnal beetles at light, both Biederman (1907) and another collector, Karl Coolidge (1911), noted a decided lack of success in obtaining specimens of C. beyeri, in spite of considerable searching about trees and in leaf litter. After finding a single specimen of C. beyeri in leaf litter, Biederman raked nearly two acres of leaves to find more beetles, but came up empty handed.

Beyer’s jewel scarab has the most restrictive distribution of all Arizona’s Chrysina and is known only from the Santa Rita, Patagonia, and Huachuca Mountains; it also occurs in the Animas Mountains of New Mexico and the states of Chihuahua and Sonora, Mexico. Adults feed on the leaves of Mexican blue oak, Quercus oblongifolia.

In 1915, Colonel Thomas Lincoln Casey, a noted and somewhat controversial coleopterist, described several species of Plusiotis, all of which have long been considered synonyms of the previously mentioned species.

Arizona’s jewel scarabs are not only popular with collectors and macro photographers, they also serve as wonderfully instructive subjects for scientific study, especially for scientists seeking to understand the physical qualities and adaptive significance of their brilliant colors. More on this subject will appear in the second and final installment of “Reflections on Arizona’s Jewel Scarabs.”

Sources:

Arnett, R. H., Jr, and R. L. Jacques. 1981. Simon & Schuster’s Guide to Insects. New York: Simon & Schuster. 511 pp.

Barnes, W. C. 1988. Arizona Place Names. Tucson, AZ: University of Arizona Press.

Biederman, C. R. 1907. Notes on Plusiotis beyeri Skinner. Entomological News 18: 7-9.

Burke, H. R. 2004. Notable Weevil Specialists of the Past. Charles Frederick August Schaeffer (1860-1934). Curculio 49: 5-7. Accessed on 26 September 2010 at: <http://www.texasento.net/Schaeffer.html#Burke>.

Calvert, P. P. 1926. The entomological work of Henry Skinner. Entomological News 37: 225-249.

Coolidge, K. R. 1911. Plusiotis beyeri Skinner. Entomological News 22: 326-327.

Evans, A. V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. New York: Sterling. 497 pp.

Hawks, D. 2001. Taxonomic and nomenclatural changes in Chrysina and a synonymic checklist of species (Scarabaeidae: Rutelinae). Occasional Papers of the Consortium Coleopterorum 4(1):  1-8.

Hawks, D. 2001. Checklist of Chrysina species (Scarabaeidae: Rutelinae: Rutelinae). (URL: http://www.unl.edu/museum/research/entomology/Guide/Scarabaeoidea/Scarabaeidae/Rutelinae/Rutelinae-Tribes/Rutelini/Chrysina/Chrysina-Catalog/ChrysinaC.html). In B.C. Ratcliffe and M.L. Jameson (eds.), Generic Guide to New World Scarab Beetles (URL: http://www-museum.unl.edu/research/entomology/Guide/Guide-introduction/Guideintro.html). Accessed on: 27 September 2010.

Horn, G. H. 1882. Notes on some little known genera and species of Coleoptera. Transactions of the American Entomological Society 10(1): 113-

Horn, G. H. 1885. New North American Scarabaeidae. Transactions of the American Entomological Society. 12: 117-128.

LeConte, J. L. 1854. Descriptions of the Coleoptera collected by Thos. H. Webb, M.D., in the years 1850-51 and 52, while Secretary of the U.S. and Mexican Boundary Commission. Proceedings of the Academy of Natural Sciences of Philadelphia 7: 220-225.

Leng, C. W. 1924. Gustav Beyer. Journal of the New York Entomological Society 32(4): 165-166.

Quincy, J. P. 1882. Memoir of Thomas Hopkins Webb. Proceedings of the Massachusetts Historical Society 19: 336-338.

Roth, G.B. 1939. An early American pharmacologist. Horatio C. Wood. 1841-1920. Isis 30(1): 38-45.

Skinner, H. 1905. Descriptions of new Coleoptera from Arizona with notes on some other species. Entomological News 16: 289-292.

© 2010, A.V. Evans

A MIGHTY MITE!

Posted in Arachnids, Predators/parasites/parasitoids with tags , , , on September 23, 2010 by Dr. Art Evans

By Arthur V. Evans

In the deserts of Africa, Asia, Europe, and North America large velvety red mites appear suddenly after heavy rains. Southwestern United States has at least two species of these amazing mites.

This past July, I came across a lone individual of a giant red velvet mite, Dinothrombium magnificum (LeConte) emerging from its burrow just east of the Patagonia Mountains in southeastern Arizona where it inhabits the Sonoran Desert and adjacent uplands.

Giant red velvet mites are spectacular for several reasons. First, the largest individuals measure in at a whopping one centimeter in length, which makes them the largest mites in the world. They are covered with a thick coat of scarlet hair-like setae. The mite’s bright red color is apparently aposematic in function and serves to warn predators of their bad taste. Entomophagous animals offered giant red velvet mites either rejected the arachnids outright or quickly spit them out.

Although often difficult to find, they are sometimes extremely abundant locally, if only for a few hours at time. For example, after a brief yet intense thunderstorm, a massive emergence of giant red velvet mites was sighted from the air at an altitude of 1500 feet just north of  Tucson. An estimated 3-5 million mites had emerged in an area roughly two acres in size!

The annual emergence of the giant mites is apparently timed to coincide with that of their primary prey, termites. However, their opportunity to gorge themselves on abundant termite reproductives is quite limited. After mating, the termites quickly shed their wings and bury themselves so that they are out of reach of the mite’s predatory embrace. Adult giant red velvet mites spend most of their lives in subterranean burrows in a diapause-like state waiting for a specific set of ecological conditions triggered by summer monsoons.

Resources:

Evans, A.V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. NY: Sterling. 497 pp.

Lighton, J.R.B. and F.D. Duncan. 1995. Standard and exercise metabolism and the dynamics of gas exchange in the giant red velvet mite, Dinothrombium magnificum. Journal of Insect Physiology 41(10): 877-884.

Newell, I.M. and L. Tevis, Jr. 1960. Angelothrombium pandorae n.g., n. sp. (Acari, Trombidiidae), and notes on the biology of the giant red velvet mites. Annals of the Entomological Society of America 53: 293-304.

Tevis, L., Jr. and I.M. Newell. 1962. Studies on the biology and seasonal cycle of the giant red velvet mite, Dinothrombium pandorae (Acari, Trombidiidae). Ecology 43(3): 497-505.

Zhang, Z.-Q. 1998. Biology and ecology of trombidiid mites (Acari, Trombidioidea). Experimental and Applied Acarology 22: 139-155.


© 2010, A.V. Evans

COW KILLERS LACK THE VELVET TOUCH

Posted in Ants, bees, wasps, Defense, Insects, Parental care, Predators/parasites/parasitoids with tags , , , , on September 22, 2010 by Dr. Art Evans

By Arthur V. Evans

Velvet ants, some of which are also known as cow killers, are actually solitary wasps. The females are wingless and sting, while the stingless males are fully winged. Although incredibly painful, the sting is seldom dangerous. Velvet ants are rarely abundant enough to need any sort of control and are best left alone to go about their business.

Velvet ant diversity is greater in southwestern United States, less so in the Southeast. Although there are more than 40 species of velvet ants found in the Southeast, only one species in the region, Dasymutilla occidentalis, stands out. It is the largest species of velvet ant in North America and occurs from Connecticut to Florida, west to South Dakota and Texas.

In spite of its nickname “cow killer,” the stings of the female D. occidentalis are not fatal to cattle. The bold and contrasting colors of this velvet ant serves to warn predators that they are quite capable of defending themselves. They also make a squeaking sound by rubbing two abdominal plates across one another as an additional warning. The stingless male is automatically defended by its close resemblance to the female.

Lone females are often seen wandering about on the ground in open habitats from spring through late summer. Winged males patrol these same habitats for mates. Both males and females drink nectar for their nourishment. After mating, females begin searching for the ground nests of bumble bees. Upon finding a nest, the female velvet ant lays a single egg at the entrance of a bumble bee nest. The larva develops inside the nest as an external parasitoid on a bee grub; pupation occurs in the bumble bee’s nest.

Resource: Evans, A.V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. NY: Sterling. 497 pp.

© 2010, A.V. Evans

TIPPING THE SCALES

Posted in Pests, Scale insects, Virginia with tags , , , , on September 19, 2010 by Dr. Art Evans

By Arthur V. Evans

Wax scales that is. Indian wax scales to be precise.

While trimming our nandina hedge this afternoon, I noticed a couple of small, white, barnacle-looking lumps on a stem. They were female Indian wax scales, Ceroplastes ceriferus (Fabricius). Sexing Indian wax scales is easy since males are not known in any wild population in Virginia. Adults are covered with a thick, white waxy layer that not only protects them from predators, parasitoids, and pesticides, but also helps them to survive freezing temperatures during the winter.

Reproduction is by parthenogenesis. One generation is produced annually in Virginia, but two or more appear in warmer climates. The first instars, or crawlers, hatch in spring and early summer and feed on leaves. They are not covered with a protective wax layer and are very susceptible to dehydration, parasites, and pesticides.

Adult Indian wax scales are conspicuous in late summer and early fall and suck sap from at least 122 plant species in 46 families. Prolific breeders, they quickly cover ornamental plants. Burgeoning wax scale populations not only ruin the plant’s appearance, but also cover them with sooty mold that develops on the prodigious amount of sticky waste (honeydew) that they produce.

Carefully tipping or lifting the scale to one side to detach the it from the plant stem reveals the orange and segmented body underneath. In the adjacent photo, the anterior of the body is on the lower right, while posterior is on the upper left. The mouthparts are visible and appear as a dark central spot at about the anterior third of the body.

Resource: Kosztarab, M. 1996. Scale Insects of Northeastern North America. Identification, Biology, and Distribution. Virginia Museum of Natural History, Special Publication No. 3. Martinsville, VA. 650 pp.

© 2010, A.V. Evans

SHARPSHOOTERS AND BROCHOSOMES

Posted in Leafhoppers, Parental care, Predators/parasites/parasitoids with tags , , , on September 17, 2010 by Dr. Art Evans

By Arthur V. Evans

Broad-headed sharpshooter, Oncometopia orbona.

Sharpshooters (Oncometopia species) measure 11-13 mm in length and are among the largest of North America’s leafhoppers. They feed on a wide variety of plants growing in gardens, parks, meadows, and woodland edges during summer and fall. Their sap feeding activities may spread plant pathogens. Females use their knifelike ovipositors to insert eggs into soft stems. The eggs are covered with a chalky substance (egg brochosomes) that make them more resistant to excess moisture and protect them from fungal infections and possibly attacks by parasitoids.

Broad-headed sharpshooter with brochosomes.

Brochosomes are intricately shaped proteinaceous particles that are produced by kidney-like structures called Malpighian tubules and excreted as a solution. After the sharpshooter molts, the solution is spread over the exoskeleton as a water-proof coating. Female sharpshooters store brochosomes as a single white dot on each forewing to be used later as a protective coating for their eggs.

© 2010, A.V. Evans

%d bloggers like this: