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What's Bugging Your Garden? Sucking Insects

What’s Bugging Your Garden 

Sucking Insects 

A number of insects, such as aphids, whiteflies, leafhoppers, spider mites, and others suck out plant juices, causing a spotty or yellow discoloration on the leaves and shoots.  The damage may be difficult to spot in the beginning, but a severe infestation may result in wilting and curling of leaves and shoots.  All sucking insects except leafhoppers congregate in large groups.  Here are the major ones to watch for.

Aphids are obnoxious pests, the bane of every gardener.  They are tiny 1/16 to 1/8 inch long, pear-shaped sucking insects in numerous colors—green, yellow, orange, black, gray, pink, brown, and even white.  The saliva of some species stunts growth and causes leaves to wilt and curl.  All aphids secrete honeydew (plant sap enriched with sugars and amino acids), which attracts ants.

Aphids have a strange life cycle.  Wingless females emerge from eggs as nymphs.  They mature and give birth to living young without being fertilized.  These young reproduce in the same way for several generations until some develop wings and fly off to other plants.  In the fall, winged males as well as females are born.  Aphids generally produce 20 or more generations each season and are found almost everywhere.


Aphids    Photo courtesy Missouri Botanical Garden Botanical Garden Plant information 

Whiteflies  are minute, 1/30 inch long, sucking insects that pierce the leaves or stems of vegetables, and draw out the sap.  They have two pairs of wings covered with a waxy powder.  Whiteflies are often present in large numbers on the undersides of leaves but go unnoticed until the plant is disturbed, when they fly out in a cloudlike swarm.  White flies secrete a sticky honeydew that becomes a growing surface for sooty black fungus.  The female whitefly lays 20 to 25 eggs that hatch into nymphs.  After feeding for some time, the nymphs enter a pupal stage from which they emerge as adult whiteflies.  Like aphids, they are found almost everywhere.

Leafhoppers are strange-looking, slender, wedge-shaped insects up to ½ inch long that damage plants by piercing them and sucking sap.  Vegetables attacked by leafhoppers often have discolored, crinkled, curled leaves and exhibit wilting or browning leaf tips and margins, often called hopperburn.  Eggplant, celery, lettuce, potatoes, and rhubarb are especially susceptible.  Adult leafhoppers migrate south in the winter and return north in the spring.  More than 2000 species are found all over North America.

 Beet leafhopper

Beet Leafhopper    Photo courtesy 

Thrips are active, needle-thin insects that look like black or straw-colored slivers.  They have two pairs of slender wings edges with long hairs.  Thrip species are named for the plants they attack.  There are onion thrips and bean thrips.  Thrips also damage carrots, cabbage, cauliflower, celery, cucumbers, melons, squash, tomatoes, turnips, and other vegetables by sucking plant juices.  Female thrips insert eggs in leaves and stems, and pale nymphs hatch in about a week and start to feed.  There are several generations a year, but they are most numerous in late spring and mid-summer.  Thrips are found worldwide.


Thrip     Photo courtesy Missouri Botanical Garden Plant Information 

There are several species of spider mites that attack vegetables, but the one most often found in home gardens is the two-spotted or red spider mite.  This tiny pest is about as big as a speck of pepper, and although it is called the red spider mite, it is more often green, yellow, or brown.  To tell whether your plants are under siege, place a piece of white paper under a small plant and shake the plant; if mites are present, some will fall on the paper and you’ll see small specks moving.  Mites lower the vitality of plants by destroying leaf tissue and by sucking nutrients.  The affected leaves turn pale green and may show blisters on the upper sides.

Mites construct silver webs over flower buds or leaves and between stalks.  They attack a number of garden vegetables, including tomatoes.  Female mites lay 100 or more eggs attached to webs on the undersides of leaves.  Mites have a one to two-week life cycle, and as many as 17 generations develop each year.  Spider mites are found everywhere in North America.

 Spider mite

Spider mites     Photo courtesy 

True Bugs 

Many people refer to all insects as “bugs,” but in actuality entomologists (insect experts) put true bugs in a class by themselves as distinct from beetles, caterpillars, and other insects.  They are relatively small creatures, 1/10 to about 5/8 inch long, with forewings that thickened toward the base and long slender beaks that suck sap out of vegetables.  Young true bugs resemble the adults except that they are even smaller.  Here are the most mischievous.

Garden flea hoppers are black, long-legged jumping “bugs” up to 1/10 inch long that attack plants by sucking out the sap.  In the spring females pierce leaves or stems and insert eggs.  There may be five generations in a season.  They are found mostly east of the Rocky Mountains.

Harlequin bugs are flat, broad, shield-shaped, 3/8 inch long and can be spotted by their unusual coloring:  black with red, orange, or yellow bands and stripes.  The green nymphs (young bugs) suck out so much sap that white or yellow blotches appear where they have fed.  If the bugs attack in sufficient numbers, leaves wilt, turn born, and die.  They are found throughout the southern half of the United States.

 Harlequin bug

Harlequin bug    Photo courtesy 

Squash bugs are 5/8 inch long and are black or brown on top, yellow underneath.  Leaves attacked by squash bugs wilt rapidly, becoming black and crisp.  They attack all vine crops, particularly squash and pumpkins.  Squash bugs spend the winter under dead leaves, boards, and similar material.  In the spring the females lay yellow eggs on the undersides of leaves.  The nymphs are bright green when they emerge and molt several times before becoming winged adults.  There is generally only one generation a year.  Squash bugs are found throughout the United States.

 Squash bug

Squash bug   Photo courtesy 

Tarnished plant bugs are ¼ inch long flat oval bugs that are streaked with brownish to yellow or yellow-black blotches.  This insect also has a clear yellow triangle marked with a black dot on the lower third of each side.  The nymphs are yellow-green with black dots.  By injecting fluid into the plant, the bug causes deformed leaves on beets and chard, wilted and discolored stems on celery, and blackened shoot tips, dwarfing, and pitting on beans.  It also attacks many other vegetables.  It is found throughout the United States.

 Tarnished plant bug

Tarnished plant bug    Photo courtesy 

A blast from the garden hose will usually send some of these insects flying off your plants, but they will return.  If they do and you find yourself with an infestation then try safe organic chemicals such as:

Hot Pepper wax  repels aphids, mites, thrips, whiteflies, leafhoppers and other insects.  Protects plants from pests by repelling them.  Made from capsaicin, an extract from cayenne peppers and paraffin wax.  Safe to humans and pets.

Safer’s Insecticidal Soap is non-toxic that works on aphids, whiteflies, plant bugs, leaf hoppers, spider mites, and other soft-bodies insects.

Bonide All Seasons Concentrate Pest Control Spray is a paraffin oil.  For aphids, bud moths, whiteflies, mealy bugs, blister mites, scale insects, red spiders.

Sharpshooter a citric acid that destroys the wax coating of the insect’s respiratory system.  Used for aphids, caterpillars, cutworms, earwigs, lacebugs, leafhopper, loopers, mites, moths, snails/slugs and whiteflies.

Safer Brand 3-in-1 Ready to use Garden spray works as fungicide, insecticide, and miteicide.  Targets and kills aphids, caterpillars, earwigs, lacebugs, mealbugs and mites.  Approved for organic gardening.

The next blog will feature borers.

© Copyright by Karen Newcomb