Southern Green Stinkbug

southern green stinkbug, Nezara viridula

Getting to Know Him

The southern green stinkbug, Nezara viridula is one tough bug.  It is said that the southern green stink bug is originally from Ethiopia.  They are from the order Hemiptera  or “true bugs”.  The family that they are in Pentatomidae.  They seem to resist almost anything, so early control is the key. It is believed that the southern green stinkbug originally came from Ethiopia.  It is now found in the tropical and subtropical areas of Europe as well as Africa and the United States.  The southern green stink bug has now moved his way to Paraguay in South America as well.  The stink bug is also found in South Argentina, and North Brazil.

Habitat

Stink bugs like to eat many of the same things you do such as beans, peas, cabbage, corn, okra, squash, tomatoes, peach, cotton, soybeans, alfalfa, citrus, ornamental plants, forage crops and many weeds.

Characteristics

I am sure you are quite familiar with the look and smell of stink bugs.  They have the shape of a shield and a five segmented antennae.  Like that is not enough they smell horrible. The southern  green stink bug adult has a rather bland green color and the familiar shield shape that you know and cringe at the site of.  The females are larger than the males measuring 13.15 mm long, and the average male measures 12.1 mm long. The females lay eggs three to four weeks after becoming adults. Females lay an average of 260 eggs during their lives.  The Southern Green Stink Bug has a very long season of laying eggs as you may know.  Eggs can be deposited as early as the second week of April and as late as the second week in December.  Each mass of eggs that are deposited contain 30 to 130 barrel shaped eggs. The eggs are light yellow to white, and as the the incubation moves forward the eggs turn pinkish.  The barrel shaped eggs also have more interesting features, they have a lid that is disc shaped (for the nymphs to get out!) There are finger -like projections around the lid called chorial processes and there are 28 to 32 of them! The eggs are very small, only 1/20 of an inch long and 1/29 of an inch wide.  Incubation time ranges from 5 days in the summer and two to three weeks in early spring and late fall.     The eggs are deposited on the underside of leaves and in the upper portions of canopied crops or weeds. The Southern Green Stink Bug favors weeds such as beggerweed, rattlebox, Mexican clover, wild blackberry and nut grass.

Instars

The nymphs look very different than the adults.  They also look very different at each instar.

First instar they have red eyes, transparent legs and antennae and are light yellow. The nymphs are only in this stage for three days before thy molt into the next stage.  They do not feed in this stage.

Second Instar the nymphs have black antennae, thorax, head and legs.  The abdomen is red and the spaces between the second, third and fourth antennal segments. The thorax has a yellow spot on each outer side.  The nymph stays in the second instar five days.

Third Instar Southern Green Stink Bug Nezara Viridula

The third instar has size differences.  The nymph stays in the third and fourth instars for seven days. In the fifth instar the nymph develops his wing pads and dull green color.  The nymph is in the fifth instar for eight days before becoming an adult.  It takes about 65 to 70 days for the southern green stinkbug to complete his life cycle.

Fourth Instar Southern Green Stinkbug Nezara Viridula

 

 

Feeding

Stink Bugs destroy your plants by using their piercing-sucking mouthparts. They pump salivary fluid  down their long beak like structure (rostrum) and liquified food is brought back up the tube like apparatus.  The green southern stink bugs prefers fruits such as tomatoes and beans as you may know.  They also feed on green shoots.  Young plants shoots may wither and die if they have been attacked by green southern stink bugs and fruit is often left unmarketable.

Sanitation

Fall cleaning of the garden and tilling are your first defense. By getting rid of the debris in your garden the harlequin bugs have no place to hide.  We have multiple seasons so turn under your crop residue as soon as you are finished with your crop.  Do not plant brassicas in the same place during the year, rotate them, so the harlequin bugs can not find them or feed on them.  Turning over the garden in the fall and planting with a cover crop will get rid of any remaining pests and their eggs.

Beneficial Insects

One bug that acts as a beneficial insect in this instance is the sow bug or pill bug.   At night the pill bug will climb up the base of the plant and feed on the eggs of the harlequin bug.  If you mulch your garden with straw the pill bugs will live in there and decompose material. The pill bugs eat the harlequin bug eggs at the same time.  Make sure to compost the straw at the end of the brassica season in a very hot compost pile to destroy any eggs that may remain.

The Tachinid fliy, Trichopoda pennipes and wasp Trissolcus basalis also parasitize southern green stink bugs eggs.  Plant flowers to encourage these beneficials.

Cover Crops

Cover cropping helps keep plants less vulnerable against bare soil, so that seedlings blend in with the landscape. The harlequin bugs have a harder time finding the young plants.

Row Covers

Using row covers will keep you protected from these pesky critters.  Fortunately if you are using row covers on members of the brassica family they do not need to be removed all season.

Trap Crop and Delayed Plantings
Mustards are a great trap crop.  Plant them earlier than your other brassicas and spray them with an organic OMRI approved insecticide to control the stink bugs.

Biorationals to Control the Stink Bug

Pyrethrins

Are made from the seed cases of  the pyrethrum flower, a species of chrysanthemum flower. It is the safest around food.

Diatomaceous Earth (Silicon Dioxide)

Ground up fossilized one celled diatoms that pierce the exoskeleton of many pests. It is used as a drench only in a powdered form.

Beauveria bassiana

This is a natural soil occurring fungi that is found in soils. It acts as a parasite to insects.  Once the droplets touch the targeted insects, they attach to the insects skin and germinate by sending out structures or hyphae that penetrate the insects body.  The insects die within 3 to 5 days. The dead insects body can be a source of spores as well. This should be done in the cooler parts of the day.

Azadirachtin 

Two active ingredients from neem tree seeds.

Heterorhabditis bacteriophora

A beneficial parasitic nematode.

Rosemary Oil

A miticide, fungicide and insecticide made from rosemary oil and other oils.  Do not use when heat exceeds 90 degrees F during the day.

Kaolin (Surround)

Kaolin clay is a particle film barrier  and can offer some protection for the organic grower.  Kaolin clay is an anti-caking agent used in toothpaste and other ingredients.  It was accepted onto the OMRI list in 2000.  It acts as a barrier between the pest and the plant by forming a film.  Make sure to spray kaolin on the underside of the plant leaves as will as that is where the harlequin bugs like to lay their eggs.

Vacuum

Yes, you heard it right, get that dust buster out early in the morning when the stink bugs are moving slow and vacuum them away. Remember to close up your garbage can tight when you take it out or they will scurry in a hurry!

Orange Oil

If you get the stink bugs while in the first three instars you can get them with orange oil.  Just remember do no use any oil if the daytime temperatures are 90 degrees F or higher or you will burn your plants.

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