Identify & Control
Garden Pests

Curled leaves/sticky honeydew/stunted growth

Neem oil/insecticidal soap/ladybugs/strong water spray

Armyworms occasionally mass migrate from grasses when their food source is being depleted. They can damage lettuce seedlings by feeding in the crown and chewing away the midrib and growing point. Once heads form, these caterpillars can bore into them, making the heads unmarketable.

Bagrada bugs insert their needlelike mouthparts into plant tissues and suck the sap. They can kill germinating seeds,seedlings, or young transplants when they feed on the apical meristem (terminal bud). White, starburst-shapedlesionsand stippled areas develop on leaves and stems, which may wilt and die. Such damage on leafy cole crops such as mizuna and other non-cole cropBrassicagreens such asarugulacan render the crop unmarketable. When bug feeding damage causes meristematic tissues to die, he

These worms feed in thecrownof the plant and can severely stunt or kill seedlings. The potential for damage is reduced between thinning and head formation. Once heads form, beet armyworms may cause serious damage by boring in from the bottom of the head which means that damage cannot be seen from above. In the San Joaquin Valley, fall populations are much more damaging than spring populations. In the central coast, beet armyworm damage starts to appear in late summer. In the low desert valleys,

While some damage is caused by nymph and adult feeding, beet leafhopper is a serious pest because it vectorsBeet curly top geminivirus.Curly top-infected plants turn yellow and stop growing.Leavesroll upward and turn purplish. Leaves and stems become stiff. Spring plantings are the most susceptible. The insect migrates from overwintering hosts in the foothills and is mostly a problem on the west side of San Joaquin Valley.

Bulb mites damage lettuce at germination only by penetrating the seedcoat as soon as germination begins. This pest is most damaging when emergence is slowed by cool, wet weather. Bulb mites can drastically reduce plant stands, especially when lettuce follows cole crops.

Holes in leaves/green caterpillars

BT spray/row covers/hand pick

Cabbage maggot feeding causes yellowing, stunting, slowed growth, and in some casesdeath of the plant. Cabbage maggots candestroy rootsof any cole crop. When larvae are numerous, they riddle the roots with tunnels, providing entryways for bacterial soft rot and the pathogen that causesblack leg. Though damage is usually restricted to the roots, heavy infestations can attack the flowering heads of cole crops.Young plants, between seedling emergence until about one month after thinning or transpla

Holes in leaves/green droppings

BT spray/row covers/hand pick

Caterpillars feed in the crown of the spinach plant and can severely stunt or kill seedlings. The potential for damage and contamination continue right up until harvest. In the San Joaquin Valley, fall populations are much more damaging than spring populations. Cutworms feed at or below ground level.

Larvae form mines on the surface of the fruit.

Defoliated plants/orange eggs underneath leaves

Hand pick/neem/spinosad/straw mulch

The corn earworm may be present throughout the season but is most abundant during August and September. Larvae feed on leaves, tassels, the whorl, and within ears, but the ears are the preferred sites for corn earworm attack.Ear damageis characterized by extensive excrement at the ear tip. Young larvae feed on corn silks, clipping them off. Shortly thereafter, they feed their way into the ear where they remain, feeding in the tip area until they exit topupatein the soil.

Corn earworms and tobacco budworms can destroy lettuce seedlings by feeding on the crown. They also bore into heads of maturing lettuce where they are difficult to control.

Corn leafhopper causes damage in two ways. First, leafhoppers directly feed on the plant, sucking out juices. Heavy populations can cause the leaves to dry; also, both the adults and nymphs produce sticky honeydew while they feed, which gets on the corn leaves. Black sooty mold frequently grows on the honeydew, reducing the photosynthetic capacity of the plant. Secondly, and more importantly, the leafhoppers transmit a pathogen calledSpiroplasma kunkelii,a bacteria-like organism that c

In California, like most of the U. S., leafminers cause little or no economic damage in corn. After hatching, the larvae burrow into the leaves where they tunnel between the upper and lower leaf surface. Larvae feed on the mesophyll, leaving behind transparent tunnels or mines. As the maggots grow the mines increase in size, and the larvae form blotchy mines rather than the more familiar serpentine mines commonly observed on vegetables. (The parallel venation of the corn leaves prevents t

Crickets generally do not cause economic losses in cucurbits. Crickets can cause some damage initially by eating flower parts and causing poor or incomplete pollination. Also, as fruit reaches the full slip stage, this pest can enter the stem end and feed internally on the fruit. Excrement of crickets can spot melons, resulting in exterior dark stains that may affect marketing value.

Holes in leaves/scarred fruit/bacterial wilt

Neem/kaolin clay/row covers/hand pick

Stems cut at soil level

Cardboard collars/diatomaceous earth/BT

These beetles chew off seedlings or feed on foliage. Damage often begins on field edges because this pest typically invades from weeds or adjacent crops. Darkling ground beetles are most active at night.

Larvae feed mostly on outer or older leaves of plants. Young stages rasp the undersides of the leaves, creating damage with a characteristic "window paning" appearance, in which the upper surface of the leaf remains intact and becomes transparent. Older larvae chew small holes or feed at the growing points of young plants and chew floral stalks and flower buds.Diamondback moth infestations are most serious when they damage the crowns or growing points of young plants or Brussels sprouts. This in

When melons are approaching maturity and are at the half slip stage, an entry point into the soft fruit tissue develops. Driedfruit beetles can enter at this site and start feeding. They can also enter at any open site caused mechanically or by other insects.

Irregular holes/hide in debris

Trap with rolled newspaper/oil traps

False chinch bugs can be an occasionally serious problem on fresh market tomato fruits. Their feeding causes indiscernible lesions on green fruits, which later become apparent as numerous, small black spots when fruits are treated with ethylene to bring on ripeness and color. Feeding on tomato foliage can cause leaves to turn brown and drop. Seedlings or newly transplanted tomatoes can be killed by the high number of migrating bugs more commonly occurring along the field edge.

Crickets are occasional pests, usually confined to sprinkler irrigated fields in the low desert. Crickets are of the concern mainly during the stand establishment when they can quickly destroy rows or even most of a field by clipping of seedling plants shortly after emergence.

Tiny holes in leaves (shot-hole damage)

Row covers/kaolin clay/diatomaceous earth

Symphylans may damage sprouting seeds, seedlings before or after emergence, or older plants. They feed primarily on root hairs and rootlets, and their ability to injure the crop decreases as plants get larger. However, their pitting of older roots may provide entryways for pathogens.

Grasshoppers destroy leaf tissue and, if present in extremely large numbers, will consume the entire plant. They may also chew on fruit, scarring the surface and netting of cantaloupes.

Hornworms feed on blossoms,leaves, andfruit. At high populations they can extensively defoliate plants and scar the fruit. They are rarely a problem in the warmer interior valleys unless natural enemies are disrupted, in which case, they can do serious damage. They are mostly problems in garden situations.

Cabbageworm larvae chew seedlings and large, irregular holes in leaves, bore into heads, and may contaminate marketed produce with greenish-brown fecal pellets. Most economic damage is to the marketed plant parts.

Skeletonized leaves

Hand pick into soapy water/neem/milky spore for grubs

The leafhopper has sucking mouthparts and can cause severe white stippling andyellowing of the leaves, green spotting of the fruit, and premature leaf drop. Large populations can reduce quality as well as yield.

Adult leafminers have such a preference for cotyledons that seedling growth may be stunted. Larvae mine between upper and lower leaf surfaces, creating winding, whitish tunnels that are initially narrow, but then widen as the larvae grow. Excessive mining renders leaves unmarketable, reduces photosynthetic capacity, and provides easy access for disease organisms.

Leafroller feeding on marketed parts of cole crops or the florets is generally minor, so direct damage from leafrollers is rarely economically significant.Leafroller larvae commonly tie one or more leaves together with silk and chew the foliage within these webbed shelters. Cole crops near native and riparian vegetation or urban landscapes may be more likely to attract leafrollers. Each leafroller species feeds on many species of plants, and adults can migrate from alternative hosts to lay their

Younglarvaefeed primarily on the undersides of lower leaves, skeletonizing them. High numbers of loopers can damage seedlings severely enough to kill them or slow growth enough to inhibit uniform maturing of the crop. Older larvae may burrow into the head from the top.

Lygus feeds by piercing cell membranes. This activity affects the subsequent cell division in the area of feeding resulting in sunken, callused lesions that could become necrotic with time. Egg laying injury is also associated with lesions. Adults lay eggs in the midrib areas of the leaf. The injury initially appears as holes or pits on the midrib and later expands into lesions.

Lacy skeletonized leaves/yellow larvae

Hand pick/neem/row covers

Infestations with the beet cyst nematode may be fairly regularly distributed throughout a field or, more commonly, may occur in several randomly distributed, localized areas. It typically takes several years before the population densities increase to levels that affect plant growth and cause obvious aboveground symptoms. Fields will have oval-shaped spots with spinach plants in the center most severely affected. The spinach appears small, chlorotic, and stunted. The symptomatic areas may

This insect feeds on a wide variety of weeds and crops. The larvae build a nest by tying leaves together with silk webbing and remain inside this nest while feeding on the surface of the leaves. When leaves lie over a fruit, or if two fruit are touching, the larva will nest between the surfaces and feed on the fruit, causing substantial scarring. Larvae do not burrow into the fruit.

Adult weevilsfeed on fruitand leaf buds.Larvae feed inside the podsandcause young fruit to dropprematurely, reducing yields. Larger fruit often do not drop when infested, resulting in crop contamination.

Potato tuberworm larvae prefer to enter the fruit at the calyx end, making a dry burrow through the core and the fleshy portions that radiate from it, but they may enter at any point on the fruit's surface. They usually spin a web over the entrance to their burrows, and the fruit must be carefully observed to detect damage.

Root-knot nematodes cause characteristic galls on roots; galls may be up to 1 inch in diameter but are usually smaller. These galls interfere with the flow of water and nutrients to the plant; infected plants are less vigorous than healthy plants, may be yellowed, are prone to wilt in hot weather, and respond poorly to fertilizer. Damage areas usually appear as irregular patches and are frequently associated with sandy or coarse-textured soils.

Saltmarsh caterpillar is rare, but serious pest of lettuce and other crops in Low Desert areas of Southern California. Larvaefeed on leavesand cause economic losses.

The larvae damage and kill germinating seeds and verysmall seedlings. Affected seedlings may wilt, be abnormally light green, and stunted. Once the stand is established and seedlings have developed a few leaves, seedcorn maggot is unlikely to cause economic damage.

Slime trails/irregular holes

Beer traps/copper tape/diatomaceous earth/iron phosphate

Stippled leaves/fine webbing

Strong water spray/neem/predatory mites

Crown mites may damage sprouting seeds, seedlings before or after emergence, or older plants. They feed primarily on newly expanding leaves at the heart of the plant. Their ability to injure the crop decreases as plants get larger and as plants grow rapidly. The damage appears as deformed leaves or as small holes in expanding leaves.

Most springtails are harmless scavengers and are considered as beneficial organisms because they aid in the decomposition of decaying plant material. However, some species may cause stunted seedling growth by damaging germinating seeds, roots and leaves of seedlings when present in large numbers. The seedlings may appear wilted and may die if damaged when young. Damage occurs as minute, rounded pits on young leaves or roots, or as irregular holes in thin leaves. Mature plants are typically not

Wilting leaves/brown spots/egg clusters

Hand pick/trap boards/neem

Wilting/sawdust-like frass at stem base

Inject BT into stem/surgery/row covers

On green fruit, damage appears as darkpinpricks, surrounded by a lightdiscolored areathat turns yellow or remains light green on ripe fruit.Fissuresbelow the surface turn corky. Stink bugs may also carry yeast and other pathogens on their mouthparts that may cause fruit decay when introduced during feeding. A few fields have been significantly damaged by yeast introduced by stink bugs; this damage is scored as "mold" by state graders.

The primary damage caused by thrips to tomatoes is the vectoring ofTomato spotted wilt virus.The virus can only be acquired by the immature stage of thrips, whereas plant-to-plant transmission primarily occurs by adults. The adult thrips can transmit the virus for the remainder of their lives, which can last 30 to 45 days. However, the adults do not pass the virus to their progeny (through the egg).High numbers of thrips can cause damage with their feeding, which distorts plant growth, deforms f

The tomato bug is also known as the tomato suck bug because both nymphs and adults will insert their long mouthparts into the stem to feed.Rings develop around stemsat these feeding sites. The rings are thickened corky areas that become yellow to reddish. The stem is weakened and brittle at these rings and can easily break when touched, causing blossom drop, dropping of young fruit, and breakage of vine stems.Tomato bugs are common in tomato fields throughout the Central Valley and in southern C

When there is fruit present, the tomato fruitworm will complete its larval development inside fruit. Early stage larvae enter the stem end of fruit when it is between 0.75 to 2 inches in diameter. During development, caterpillars may emerge from one fruit and enter another. Their feeding results in amessy, watery, internal cavityfilled with cast skins and feces. Damaged fruit will ripen prematurely. Late in the season, small larvae will also enterripe fruit. Small larvae are difficult to detect

Defoliated stems/dark droppings/missing fruit

Hand pick/BT spray/parasitic wasps

This caterpillar feeds on leaves and createsblotch-type mines, but causes most of its damage when it attacks thefruit. Where abundant, the tomato pinworm may seriously damagefoliageand infest nearly 100% of the fruit. Larvae normally enter fruit through thecalyx, but when populations are high they may enter at any point on the fruit's surface. They makedry burrowsand do not penetrate very far into the fruit. When infested fruit is picked, caterpillars may be difficult to detect unless they have

Nymphs and perhaps adults inject a toxin while feeding on the leaf that causes death in transplants, stunting, chlorosis and curling of leaves in preflowering plants, and either no fruit production or overproduction of very small, noncommercial-grade fruit in larger plants. These symptoms are collectively known as "'psyllid yellows"' or "vein greening". A bacterium, calledCandidatusLiberibacter psyllaurous orCa.L. solanacearum, has also been associated with these symptoms in tomatoes.

Russet mites remove cell contents from leaves, stems, and fruit cells. Usually starting near the ground, infestations of this mite progress up the plant and lower leavesdry out, giving the plant an unhealthy appearance. The color of the stems and leaves frequently becomesgreasy bronze or russet colored. If not controlled, this pest can kill plants.

Damage is similar to the driedfruit beetle in that the presence of vinegar flies in fruit causes downgrading or rejection of fruit. Vinegar flies are also responsible for transmitting spoilage organisms to sound fruit. Late ripening varieties are especially susceptible to damage as vinegar flies become widespread in tremendous numbers.

Western flower thrips feed on lettuce and vector plant viruses. Thrips cause injury to lettuce bypuncturing leaves and sucking the plant sap. Punctured leaves take on a silvery appearance that eventually turns to brown scarring and can be confused with windburn or blown sand damage. Look for the presence of small, black fecal specks in the damaged area to confirm thrips damage.Western flower thrips is the most important vector ofTomato spotted wilt virusand the only known thrips species to vecto

This pest feeds on both foliage and fruit. It rarely bores deeply into the fruit, but eats on the surface, causingirregular holes. Infestations are typically sporadic occurring in some years, and when a problem, most severe from July to mid-September.

Sticky honeydew/sooty mold/tiny white flies

Yellow sticky traps/neem/insecticidal soap

Wireworm larvae injure crops by partially or completely devouring seeds in the soil, thus reducing plant stands. On plants, they can cut off small, underground stems and roots or bore into larger ones.