Pests are unwanted plants, animals, insects, germs or other organisms that interfere with human activity. They may bite, destroy food crops, damage property, or otherwise make our lives more difficult.

1. Insect Pest Control
Methods
LNT 136 – Spring 2017
Mark Valen

2. Integrated Pest Management
• Set Action Thresholds
• Identification
• Prevention
• Control

3. Action Thresholds
• An Action Threshold is an acceptable level of pest
damage above which you will decide to take action

4. Monitoring

5. Management
• Cultural Control
• Pick trees suited to location
• Avoid excess nitrogen
• Add supplemental water during drought
• Avoid stock‐piling cut lumber
• Avoid injuring trees
• Look for resistant varieties

6. Management
• Mechanical Control
• Prune out heavily infested branches

7. Management
• Physical Control
• washing foliage
• Barriers such as sand, salt, copper shields.

8. Natural Enemies
• Parasites
• Pathogens
• Predators
• Birds
• Lizards

9. Insecticides
• Biological
• Bacillus thuringiensis (Bt)
• Nematodes

10. Insecticides
• Botanicals
• D‐limonene
• Pyrethrum
• Neem Oil

11. Insecticides
• Inorganics
• Diatomaceous earth
• Sulfur
• Borate (boric acid)

12. Insecticides
• Insecticidal Soaps
• Effective against soft bodies insects
• Can cause damage to delicate plants

13. Insecticides
• Oils
• Foliar sprays
• Delayed‐dormant applications
• Can be mixed with soaps

14. Insecticides
• Carbamates, Organophosphates, Pyrethroids
• Synthesized from petroleum products
• Kills when directly applied or pest contacts residue
• Also kills beneficials
• Cause of pollution

15. Insecticides
• Neonicotinoids
• Systemic pesticide; translocates within the plant
• Can be absorbed by plant roots, bark, or foliage
• Can control for specific types of pests
• May impact beneficials

16. Argentine Ant
• Workers are all the same size, small,
1/8‐inch long
• Uniformly dull brown
• Feed on sweets, fresh fruit, and buds
of some plants
• Tend honeydew‐producing species
• Distinctive trails along branches of
trees and shrubs
• Outdoors in soil, under wood, slabs,
debris, mulch, or in branches and
cavities of trees and shrubs
• Shallow, 1‐ to 2‐inch deep mounds in
open, often disturbed habitats,
either moist or dry

17. Aphids
• Pear, shaped insects.
• Can be green, brown,
black, or white.
• Suck plant juices out of
young, tender plant tips.
• Excrete a sticky honeydew.
• Honeydew leads to black
sooty mold.
• Ants may protect them.

18. Bagrada Bugs
• Stink bug that attacks plants
within the mustard family
(Brassicaceae)
• First found in Los Angeles
County in 2008.
• By 2011, the pest had
disseminated throughout
Southern California to include
San Diego, Imperial, Orange,
Riverside, San Bernardino, and
Ventura counties.
• Often confused with the native
Harlequin bug

19. Gold Spotted Oak Borer
• Introduced to San Diego County,
California, in the late 1990s or early
2000s
• Likely brought into the state on oak
firewood collected and transported
from the insect’s native range in
southeastern Arizona or northern
Mexico.
• Prefers mature oak trees, but it
occasionally attacks smaller oaks
with a diameter at breast height
(dbh) of about 10 inches.
• Cause crown thinning and dieback,
bark staining on the main stem, bark
injury from woodpecker foraging,
and D‐shaped emergence holes on
the main stem and larger branches
of the tree, eventual tree death.

20. Glassy‐winged Sharpshooter
• Introduced to southern California in
the early 1990s.
• Large leafhopper that feeds on plant
fluids in the xylem
• Feeding rarely causes significant
damage
• Can spread the disease‐causing
bacterium Xylella fastidiosa from
one plant to another
• This bacterium is the causal agent of
devastating plant diseases such as:
• Pierce’s grape disease
• Oleander leaf scorch
• Almond leaf scorch
• Mulberry leaf scorch
• Sweet gum dieback
• Cherry plum leaf scorch

21. Grasshoppers
• Large populations may
build up in foothills and
rangelands, especially
after a wet spring, and
then migrate into nearby
gardens, often
defoliating everything in
sight.
• More than 200 species of
grasshoppers occur in
California, but only a few
of these cause significant
problems in gardens.

22. Mealybugs
• Soft, oval, wax‐covered
insects
• Feed on many plants.
• Piercing‐sucking insects
• Like soft scales, they can
produce abundant
honeydew and are often
associated with black
sooty mold.
• Favored by warm
weather

23. Psyllids
• Flattened, round insects
related to aphids.
• Nymphs suck plant juices
leaving a round pit on
the leaf.
• Adults have wings &
jump when disturbed.
• Eugenias, pepper trees,
mallows.

24. Asian Citrus Psyllid
• Mottled brown insects.
• Feeds on all varieties of
citrus
• Vector for fatal
huanglongbing (HLB)
disease
• HLB can kill a citrus tree in
as little as five years, and
there is no known cure

25. Scale
• Round, turtle shaped
insects with a waxy
covering.
• Have long piercing
mouth parts that suck
plant juices.
• Soft and armored
scales exist.

26. Cottony Cushion Scale
• Soft, sticky scale insect
with distinctive rippled
body.
• Sucks plant saps from
leaves and stems.
• Slowly kills leaves and
branches.
• Produces honeydew.

27. Snails
• Belly‐footed organisms.
• Feed on live plants and
decaying matter.
• Live in dark moist
locations.
• Young seedlings are
very susceptible.

28. Spider Mite
• Small, almost microscopic
organisms related to ticks
and spider.
• Pierce and suck out plant
juices.
• Cause stippling of the leaf
surface, it looks dull and
“sandblasted”

29. Thrips
• Slender, 1/16” long
insects that rasp at the
leaf surface.
• Can be white, yellow,
or black.
• Leave behind shiny
fecal matter on leaf
• Turn leaf silvery or
bronzy.

30. Whitefly
• Tiny, sap‐sucking insects
• May become abundant in
vegetable and ornamental
plantings, especially during
warm weather.
• They excrete sticky
honeydew and cause
yellowing or death of leaves.
• Outbreaks often occur when
the natural biological
control is disrupted.
• Management is difficult
once populations are high.