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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/

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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Cotton aphid/Melon aphid

Article author: David Kerns
Most recently reviewed by: Pat Porter (2018)

Common Name(s): Cotton Aphid, Melon Aphid

Pest Location

Row Crop, Vegetable and Fruit

Description

Cotton or melon aphids, Aphis gossypii, are highly variable in size and color, varying from light yellow to dark green or almost black. Although size can vary based on environmental conditions, adult aphids tend to be about 1/16th inch in length, are soft bodied and pear shaped. Aphids have piercing-sucking mouthparts and have two protrusions on their rear tips called cornicles. Aphid adults can be winged (alate) or wingless (apterous). The formation of winged types is usually in response to overcrowding or poor host quality. The immatures or nymphs of the aphid are similar in appearance to the adult but smaller.

Origin and Distribution

Cotton aphid is nearly cosmopolitan, having a world-wide distribution. However, host specificity does vary depending on geographic origin.

Habitat & Hosts

Cotton aphids are extremely polyphagous and can feed on a large range of host plants covering 25 plant families. Among many others, notable hosts include asparagus, beans, begonia, catalpa, citrus, clover, cucurbits, cotton, eggplant, ground ivy, gardenia, hops, hibiscus, hydrangea, okra, peppers, potato, spinach, strawberries, tomatoes and violet. Crops typically most affected by cotton aphids include citrus, cotton and hibiscus.

Cotton aphids will initially be found feeding on the underside of new leaves, the plant terminal and flower buds, but as the population grows will infest the under side of older leaves.

Cotton aphids feed using sucking-piercing mouthparts which they use to pierce leaves and ingest copious amounts of plant sap from the phloem. Feeding robs the plant of energy that would otherwise be utilized for growth or fruit production. Heavy and prolonged infestations can cause leaves to curl downward, older leaves to turn yellow and shed, plant fruit may also shed or suffer reduction in size.

Cotton aphids excrete wastes in the form of a syrup-like substance called honeydew. Honeydew will accumulate on the leaves (and other plant structures) giving them a shiny, sticky appearance. A black sooty mold will often grow on the honeydew covering the leaf which may partially inhibit photosynthesis. More importantly, the honeydew may accumulate on the lint of open cotton bolls rendering the lint undesirable for milling.

Cotton aphid is also an important vectors of over 50 plant viruses including cucumber mosaic virus, watermelon mosaic virus 2, and zucchini yellow mosaic virus. These viruses are non-persistent viruses and may be transmitted from aphid to plant in a little as 15 seconds.

Cotton aphids are often attended by ants, which collect an feed upon their honeydew.

Life Cycle

With exception of northern latitudes, cotton aphids in the United States are all females, reproduce asexually (parthenogenically), giving birth to live young without mating. Aphids have a tremendous reproductive capacity and nymphs are born with developing embryos already present; essentially aphids are born pregnant. One female may produce as many as 80 offspring that mature within 8 to 10 days. Thus, it is possible for cotton aphids to have as many as 50 generations per year. These generations also occur as frequently as every 5 to 7 days under optimum conditions. In northern latitudes cotton aphid is capable of producing sexual forms and laying eggs on catalpa and rose of sharon for overwintering purposes.

Wingless adults overwinter in protected areas on catalpa, hibiscus, and a number of weed hosts. In the greenhouse, they can be active year-round. In spring winged females fly to suitable host plants and can disperse great distances via wind and weather fronts.

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.

Predators such as lady beetles, lacewings and syrphid flies, along with parasitoids and aphid-killing fungi are often the most effective means of managing an cotton aphids. These beneficial organisms can effectively prevent aphids from reaching the damaging levels. Aphid tending ants will often protect aphids from predators. Soil and seed applied insecticides offer protection during early plant growth, but foliarly applied insecticides are often necessary on more mature plants. Standard and organically certified insecticides are available, but cotton aphid is notorious for developing resistance to commonly used insecticides so adequate control is not certain.

Related Publications

Citations

Blackman, R.L. and V. F. Eastop. 2000. Aphids on the worlds crops: an identification and information guide 2nd edition. Chichester, UK: John Wiley & Sons Ltd.

Kerns, D.L., J.A. Yates and B.A Baugh. 2015. Economic threshold for cotton aphid (Hemiptera: Aphididae) on Cotton in the Southwestern United States. J. Econ. Entomol.108: 1795-1803.

Suhas, V., D. Kerns, C. Allen, R. Bowling, M. Brewer and M. Parajulee. 2017. Managing cotton insects in Texas. ENTO-075, 38 pp. http://www.agrilifebookstore.org/Managing-Cotton-Insects-in-Texas-p/ento-075.htm.

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Blackmargined aphids (Pecan)

Article author: Bill Ree
Most recently reviewed by: Pat Porter (2018)

Common Name(s): Blackmargined Aphid

Pest Location

Vegetable and Fruit

Description

There are three species of foliage feeding aphids on pecan: the blackmargined aphid, Monellia caryella; yellow pecan aphid, Monelliopsis pecanis and black pecan aphid, Melanocallis caryaefoliae. Of these three, the blackmargined and yellow pecan aphid are also referred to a yellow aphids or honeydew aphids.

The winged adult blackmargined aphid can be identified by the wings being held in a horizontal position and by the black margins along the wing, Figure 1. The yellow pecan aphid, has clear wings which are held roof-like over the back of the body.

Habitat & Hosts

Blackmargined aphids can be found on pecan, Carya illinoensis (both improved cultivars and native trees) across the pecan belt. They are also found on water hickory, Carya aquatica.

Life Cycle

Blackmargined pecan aphids overwinter as eggs under the bark of trees. Nymphs emerge during the spring and feed primarily on the underside of the leaf on the primary and secondary leaf veins, Figure 2. During the summer, many generations of aphids are produced by unmated females giving birth to live female aphids. The time period from birth to adult is approximately 6 days and there can be 16 to 32 generations per year. All aphids during the growing season are females which give birth to live young. Males are not produced until the fall. Mature males mate with females and the females lay the overwintering eggs.

Both adults and nymphs feed on plant sap and excrete a sticky substance referred to as honeydew, Figure 3. A black sooty mold will grow in the honeydew which, if heavy enough, will reduce the photosynthetic ability of the foliage, Figure 4.

 

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.

Primary management of blackmargined aphids is with insecticides. Management options with insecticides include the use of several active ingredients that are selective for aphids as well as other insects that feed on plant sap.

Other suggestions for aphid management include only treating problem varieties (if practical), treating only when insect densities exceed the treatment threshold of an average of 25 aphids per compound leaf, and rotating insecticides with different modes of action.

Other management options can include planting winter legume cover crops to generate populations of beneficial predatory insects such as lady beetles and lacewings during the spring. Also, using insecticides selective for Lepidoptera pests when treating for early season insects such as the pecan nut casebearer can help conserve existing populations of beneficial insects.

Two of the main beneficial insect groups which prey on pecan aphids are lacewing larvae (Figure 5) and lady beetle adults and larvae (Figures 6 and 7). Pecan aphids are also parasitized by a small wasp, Aphelinus perpallidus. Parasitized aphids turn black (Figure 8) and should not be mistaken for the black pecan aphid.

 

Figure 5, Lacewing larvae Bill Ree, Texas A&M AgriLife Extension

Figure 5, Lacewing larvae
Bill Ree, Texas A&M AgriLife Extension

Figure 6. Lady beetle adults Bill Ree, Texas A&M AgriLife Extension

Figure 6. Lady beetle adults
Bill Ree, Texas A&M AgriLife Extension

Figure 7. Lady beetle larvae Bill Ree, Texas A&M AgriLife Extension

Figure 7. Lady beetle larvae
Bill Ree, Texas A&M AgriLife Extension

Figure 8. Black aphid mummies of parasitized blackmargined pecan aphids Alejandro Calixto, Texas A&M AgriLife Extension

Figure 8. Black aphid mummies of parasitized blackmargined pecan aphids
Alejandro Calixto, Texas A&M AgriLife Extension

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