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Black-and-yellow Argiope, Zipper Spider, Corn Spider

Article author: John Few
Most recently reviewed by: Janet Hurley (1970)

Common Name(s): Black-and-yellow Argiope, Corn Spider, Zipper Spider

Description

Argiope aurantia sexual dimorphism

Argiope aurantia sexual dimorphism. Photo by Troy Bartlett.

The word Argiope means “with a bright face” in Latin. Like all spiders, they have a cephalothorax, abdomen, eight legs, fangs, and a silk spinner. Being an orb weaver, spiders in the genus Argiope spp. have a unique third claw on each leg that is used to assist in the weaving of the spider’s complex webs. Their webs are often large and have a zig-zag pattern in the center. The reason for this pattern is unknown, though it is thought that it may be used to attract prey. Argiope spp. spiders consume and rebuild their web every day. Known for their black and yellow patterns on their body, and occasionally an orange and/or black pattern on their legs, these spiders are incredibly beautiful and easily recognized. As with most spiders the females of this genus are larger than their male counterparts. Females are usually around ¾” to 1 ⅛” while males are usually ¼” to ⅜” in size.

Origin and Distribution

Found all over the world and in the lower 48 states of the U.S.A

Habitat & Hosts

Argiope spp.  spiders are not a pest in the traditional sense of the word as they do not feed on crops or garden plants, but to those who are afraid of spiders it can be considered a pest. As with most spiders, Argiope spp. are beneficial organisms because they kill and consume insect pests that damage crops and garden plants.

Life Cycle

Argiope spp. mate once a year. Mature male spiders roam in search of potential mates. Once a suitable mate has been found, the male then builds a web with a zig-zag pattern either in the middle of or on the outer area of the female’s web and begins to pluck the female’s web as a courting gesture. Once impregnated females lay one or more egg sacs in her web close to her resting position. Each egg sac contains anywhere between 300 to 1400 eggs. The mother watches over her eggs but will usually die at the first hard frost. Spiders usually hatch around autumn or summer and look similar to their adult counterparts. Most spiders usually live for around a year though some females can live for multiple years in warmer climates. Most males usually die after mating.

Citations

Hammond, G. 2002. “Argiope aurantia” (On-line), Animal Diversity Web. Accessed April 17, 2020 at https://animaldiversity.org/accounts/Argiope_aurantia/

Hawkinson, C. ND, “Galveston Master Gardeners Beneficials in the Garden, Black and Yellow Argiope Spider” (On-line), Aggie-Horticulture, Accessed April 17, 2020 at https://aggie-horticulture.tamu.edu/galveston/beneficials/beneficial-24_spider_blackandyellow_argiope.htm

Murray, M. 2018. “What is a spider” (On-line), Australia Museum, Accessed April 17, 2020 at https://australianmuseum.net.au/learn/species-identification/ask-an-expert/what-is-a-spiders/

Silverleaf whitefly

Article author: Erfan Vafaie
Most recently reviewed by: Pat Porter & David Kerns & Suhas Vyavhare (2018)

Common Name(s): Silverleaf Whitefly, Sweetpotato whitefly

Description

The silverleaf whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a global pest of many economically important host plants (Simmons et al. 2008) such as eggplant, tomato, sweet potato, cucumber, garden bean (Tsai & Wang 1996), cotton, and poinsettias, to name a few. Similar to other sucking insect pests, silverleaf whiteflies reduce plant vigor, growth, and can even cause mortality by piercing plant tissue and feeding on plant phloem (Bryne & Miller 1990). Whiteflies excrete waste as a sugary solution, known as honeydew. Excessive honeydew can result in inoculation of a complex of fungi, resulting in a black layer or crust forming on the surface, commonly referred to as sooty mold. In addition to causing detrimental damage by feeding, B. tabaci has been recorded to vector more than 100 plant viruses (Jones 2003), which can result in rapid widespread crop loss. Some of these viruses in Texas include Cucurbit leaf curl virus (Brown et al. 2000) and cucurbit yellow stunting disorder virus (Kao et al. 2000).

Adult whiteflies resemble very small (1 mm or 3/64-in) white moths. When disturbed, adult whiteflies will often leap off the plant and fly a short distance before landing on a nearby surface. Whitefly nymphs, especially younger nymphs, can be hard to see with the naked eye. Whitefly nymphs often blend with the leaf due to their color and relatively flat shape. The final nymph instar is often referred to as a pupa, when they become darker yellow color and are more round, making them easier to distinguish on the leaf. Once they emerge as adults, their shed ‘skin’ stays on the leaf, known as an exuvia. The exuviae stay on the leaf and resemble a small empty shell.

Adult silverleaf whiteflies can be confused for other whiteflies that may occur in Texas, with two other common ones being the badedwing whitefly (Trialeurodes abutiloneus) and greenhouse whitefly (Trialeurodes vaporariorum).

Origin and Distribution

Silverleaf whiteflies are considered a global pest, however there are certain biotypes or species that are more prevalent in different parts of the world. Texas has populations of both MEAM1 (B biotype) and MED (Q biotype) whitefly.

Life Cycle

Whiteflies are closely related to mealybugs and scale insects. Female adult whiteflies lay eggs, often in a circular pattern as result of the female using her feeding proboscis as a pivot while laying eggs. Eggs are pear-shaped and approximately 0.2 mm long (CABI MEAM1). On cotton, eggs take between 5 to 22.5 days to emerge as crawlers when held at 16.7ºC (62F) or 32.5ºC (90.5) (Butler et al. 1983), respectively. After emerging from the eggs, a mobile stage known as “crawlers” find a place nearby to settle. Once settled, whitefly nymphs are considered rather immobile until after metamorphosis. Bemisia tabaci undergo four instar stages before pupation and becoming a winged adult. The total development time from egg to adult varies from 16.6 days at 30ºC (86F) to 65.1 days at 14.9ºC (59F) in cotton (Butler et al. 1983). Adult females lay approximately 72 – 81 eggs and survive an average of 8 to 10.4 days in controlled studies (Butler et al. 1983).

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Silverleaf whitefly taxonomy is currently under revision, but it is generally agreed upon that there are specific groups of silverleaf whiteflies that exhibit different host plant preferences, reproductive rates, and resistance to insecticides. Originally, it was thought that silverleaf whiteflies were composed of several different ‘biotypes’, a couple well-known ones including the “B” (MEAM1) and “Q” (MED) biotypes, but now has been proposed to be made up of at least 34 morphologically indistinguishable species (Tay et al. 2012). The MEAM1 whiteflies have greater reproductive potential than the MED whiteflies, however the MED whiteflies are resistant to several different insecticides, such as pyriproxyfen and imidacloprid. Growers are encouraged to either use biological control to prevent further rise of resistance to insecticides, or rotate between insecticides that are known to be effective against both MEAM1 and MED whiteflies. See “Related Publications” below for more information.

Whitefly populations can be monitored using yellow sticky cards or searching the undersides of leaves for eggs, nymphs, pupae, exuviae, or adults. Look for other signs of infestation, such as honeydew, sooty mold, or chlorosis.

In many regions of Europe and North America, silverleaf whiteflies in protected culture (i.e. greenhouses) are managed through regular releases of biological control agents. In the USA, commercially available biological control agents that have demonstrated potential management of silverleaf whiteflies include Eretmocerus eremicus (Hoddle and van Driesche) and Amblyseius swirskii (Calvo et al. 2010).

Insecticidal management of silverleaf whiteflies are highly dependent on commodity, location, setting, and thresholds. Some active ingredients that have demonstrated efficacy against both MEAM1 and MED silverleaf whiteflies include:

  • Abamectin
  • Abamectin + Bifenthrin
  • Acetamiprid
  • Beauvaria bassiana
  • Cyantraniliprole
  • Dinotefuran
  • Isaria fumosorosea
  • Horticultural Oil*
  • Insecticidal Soap*
  • Pyridaben
  • Pyrifluquinazon
  • Spiromesifen
  • Spirotetramat
  • Thiamethoxam

(Kumar et al. 2017)
*Beware of application in extreme heat and exposure to sun. Can cause leaf burn/phytotoxicity.

For more information, consult one of our related publications below for whitefly management specific to your situation.

Related Publications

CABI Bemisia tabaci (MEAM1) fact sheet: https://www.cabi.org/isc/datasheet/8925#8440C199-FEDE-40E6-AED0-E7C195DC4E5B

CABI Bemisia tabaci (MED) fact sheet: https://www.cabi.org/isc/datasheet/112682

Byrne, David N. (1991). Whitefly biology. Annual Review of Entomology, 36: 431 – 457.

Suhas et al. (2018). Managing Cotton Insects in Texas. Texas A&M AgriLife Extension. https://agrilife.org/extensionento/resources/management-guides/managing-cotton-insects-in-texas/other-pests/

Kumar et al. (2017). Whitefly (Bemisia tabaci) management program for ornamental plants. UF/IFAS Extension. https://mrec.ifas.ufl.edu/lso/bemisia/Documents/EDIS-Whitefly-Management-Program.pdf

Citations

Brown et al. (2000). Cucurbit leaf curl virus, a new whitefly transmitted geminivirus in Arizona, Texas, and Mexico. The American Phytopathological Society, 84(7): 809.

Butler et al. (1983). Bemisia tabaci (Homoptera: Aleyrodidae): Development, oviposition, and longevity in relation to temperature. Annals of the Entomological Society of America, 76: 310 – 313.

Byrne & Miller (1990). Carbohydrate and amino acid composition of phloem sap and honeydew produced by Bemisia tabaciJournal of Insect Physiology, 36: 433 – 439.

CABI Bemisia tabaci (MEAM1) fact sheet: https://www.cabi.org/isc/datasheet/8925#8440C199-FEDE-40E6-AED0-E7C195DC4E5B

Calvo et al. (2011). Control of Bemisia tabaci and Frankliniella occidentalis in cucumber by Amblyseius swirskii. 56(2): 185 – 192.

Hoddle, M. and van Driesche, R. G. (1999). Evaluation of inundative release of Eretmocerus eremicus and Encarsia formosa Beltsville strain in commercial greenhouses for control of Bemisia argentifolii (Hemiptera: Aleyrodidae) on poinsettia stock plants. Biology and Microbial Control, 92(4): 811 – 824.

Jones D (2003). Plant viruses transmitted by whiteflies. European Journal of Plant Pathology, 109: 197 – 221.

Kao et al. (2000). First report of Cucurbit yellow stunting disorder virus (genus Crinivirus) in North America. The American Phytopathological Society, 84(1): 101.

Kumar et al. (2017). Whitefly (Bemisia tabaci) management program for ornamental plants. UF/IFAS Extension. https://mrec.ifas.ufl.edu/lso/bemisia/Documents/EDIS-Whitefly-Management-Program.pdf

Simmons et al. (2008). Forty-nine new host plant species for Bemisia tabaci (Hemiptera: Aleyrodidae). Entomological Science, 11: 385 – 390.

Tay et al. (2012). Will the real Bemisia tabaci please stand up? PLoS ONE, 7(11): 7 – 11.

Tsai & Wang (1996). Development and reproduction of Bemisia argentifolii (Homoptera: Aleyrodidae) on five host plants. Environmental Entomology, 25(4): 810 – 816.

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Banded Cucumber Beetle

Article author: Charles Allen
Most recently reviewed by: David Kerns (2018)

Common Name(s): Banded Cucumber Beetle

Description

Adults are 1/5 to 1/4  inch long. They are light green with 4 broken yellow bands across the back (elytra). The bands vary among insects and are sometimes barely visible. The head, antennae and distal leg segments are reddish brown. They can be found on plants feeding on leaves and flower parts.

The larvae range from 1/10 to 1/3 inch and are off-white, cream colored or pale yellow with dark brown heads and anal plates. They are found below ground feeding on plant crowns and roots.

Origin and Distribution

Banded cucumber beetles are believed to have originated in tropical areas of the new world. It can currently be found in the southern states from California to Florida and North Carolina. Tropically adapted, it is not likely to be able to survive farther north in the United States.

Habitat & Hosts

Besides the crops listed above banded cucumber beetle feeds on a number of other host plants. It is reported to feed on gourd, amaranth, crownbeard, silverleaf nightshade and mulberry.

Life Cycle

Adults emerge and begin mating within about 6 days. Eggs are laid about 16 days after mating. Egg laying continues for two to eight weeks. Eggs are laid in clusters of about 100 eggs each and females produce two to 15 egg clusters – up to 850 eggs per female. Adults live an average of 26 days (range: 17 to 44 days). Eggs are pale yellow, oval, 0.6 mm in length and 0.35 mm in width. They are laid in cracks in the soil and hatch in five to nine days.

There are three larval stages. The larvae are worm-like, and cream colored with brown heads and anal plates. They range in length from 0.1 to 0.35 inches. Larvae complete development in 11-17 days. Larvae pupate in the soil, resting there for four to six days.

Banded cucumber beetles can produce six to seven generations per year. The species is not reported to go into winter diapause.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Soil and seed applied insecticides have been used to control the destructive larval stage in crops. Foliar insecticides are sometimes needed to control adult beetles. Weed control can help reduce damage to seedling crops.

Related Publications

http://entnemdept.ufl.edu/creatures/veg/bean/banded_cucumber_beetle.htm

https://en.wikipedia.org/wiki/Diabrotica_balteata

Citations

CABI. 2006. Distribution Maps of Plant Pests. CABI Wallingford, UK. Map 681.

Chittenden FH. 1912. Notes on the cucumber beetles. USDA Bureau of Entomology Bulletin 82: 67-75.

Marsh HO. 1912. Biologic notes on some species of Diabrotica in southern Texas. USDA Bureau of Entomology Bulletin 82: 76-84.

Pitre Jr HN, Kantack EJ. 1962. Biology of the banded cucumber beetle, Diabrotica balteata, in Louisiana. Journal of Economic Entomology 55: 904-906.

Saba F. 1970. Host plant spectrum and temperature limitations of Diabrotica balteata. Canadian Entomologist 102: 684-691.

 

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Grasshoppers

Article author: Pat Porter
Most recently reviewed by: Ed Bynum (2018)

Common Name(s): Differential Grasshopper, Grasshoppers, lubber grasshopper, migratory grasshopper, Packard grasshopper, red-legged grasshopper, two-striped grasshopper

Description

Grasshoppers undergo gradual metamorphosis as the nymphs (immature insects) molt to the next growth stage. This means that nymphs look very much like adults, except that the nymphs do not have fully developed wings. If a grasshopper’s wings are fully developed, then it is an adult. The long hind pair of legs is well adapted for jumping, and adults are good fliers over short distances.

There are many color variations according to species, and many species are well camouflaged and difficult to see unless they move. Other species are brightly colored.

All grasshoppers have mandibles (teeth) and damage plants by chewing chunks of tissue from leaves and other plant parts. The feeding usually begins on outside edges of leaves and the chewed area has ragged or irregular edges. This often looks quite different from the smoother, more even damage done by caterpillars.

 

Origin and Distribution

Grasshoppers are distributed worldwide and occasionally reach serious pest outbreak status causing major crop loss. Occasionally, large flights of grasshoppers are detected on radar.

Habitat & Hosts

Almost any type of plant including corn, alfalfa, Bermudagrass, cotton, millet, peanut, rice, ryegrass, sorghum, Sudangrass, soybean, sugarcane, vegetables, wheat, flowers and landscape plants.

Life Cycle

Grasshoppers deposit their eggs 1⁄2 to 2 inches below the soil surface in pod-like structures. Each egg pod consists of 20 to 120 elongated eggs cemented together. The whole mass is somewhat egg-shaped. Egg pods are very resistant to moisture and cold and easily survive the winter if the soil is not disturbed.

Eggs are deposited in fallow fields, ditches, fencerows, shelter belts and other weedy areas, as well as in crop fields, hay fields and alfalfa. Eggs begin hatching in late April or early May. Hatching peaks about mid-June and usually ends by late June. If spring weather is cool and extremely dry, hatching may be delayed and continue into July.

Young grasshoppers are called nymphs, and they undergo simple metamorphosis. They look like adults, but are smaller and have wing pads instead of wings. Nymphs go through five or six developmental stages and become adults in 40 to 60 days, depending on weather and food supplies. The adults of grasshopper species that damage crops become numerous in mid-July and deposit eggs from late July through fall. Usually only one generation of grasshoppers is produced each year.

Grasshoppers have a high reproductive capacity. The female lays an average of 200 eggs per season, and sometimes as many as 400 eggs. If favorable weather increases the number of eggs, the grasshopper population may be dramatically larger the following year. Grasshoppers cause some damage every year, but they become very destructive during outbreaks. The main factor affecting grasshopper populations is weather. Outbreaks, or exceptionally large populations, are usually preceded by several years of hot, dry summers and warm autumns. Dry weather increases the survival of nymphs and adults. Warm autumns allow grasshoppers more time to feed and lay eggs.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Nosema locustae is a protozoan that can be purchased commercially to treat large areas. Its spores have been incorporated with bran to make insecticide baits such as Semaspore®, Nolo Bait® or Grasshopper Attack®. These baits kill some nymphs but almost no adults, though infected adults lay fewer eggs. Baits act too slowly and kill too few grasshoppers to be useful for immediate control.

When grasshoppers are at low numbers, handpicking them is an option. However, when at high numbers control becomes very difficult and insecticides are warranted.

Home garden control options include:

  • Carbaryl (Sevin)
  • Neem
  • Pyrethrins
  • Synthetic pyrethroids

Related Publications

 

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