An Introduction to Insects · Digestive tract Defensive glands Communication glands Insect exoskeleton Photo ® Van Waters & Rogers / Made of chitinous proteins strong resilient ideal
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Master Gardener TrainingMichael E. Merchant, PhD, BCE
m-merchant@tamu.edu
Copyright Texas AgriLife Extension
An Introduction to Insects
Texas Cooperative Extension
What are insects and mites?
Phylum Arthropodabilaterally symmetricalhard outer exoskeletonsegmented bodiesjointed legs
Arthropod Examples
Lobsters, crabs, shrimp (Crustacea) Spiders, mites, scorpions (Arachnida)Centipedes, millipedes (Chilopoda) Insects (Hexapoda)
the most diverse form of life on the planet
Recent estimates of species diversity• 1.2 million species
described• Total estimated species
count: 8.7 million (Eukaryotes)• 2.2 million marine
• 86% of existing species undescribed (96% of marine species)
(Mora et al. 2011)
Three main body regions
• Six legged• Antennae• Metamorphosis
Insect Characteristics
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Head: Center for sensory perception
Photo ® Van Waters & Rogers /
Eyes Palpi
Antennae
Thorax: Center for movement
Photo ® Van Waters & Rogers /
LegsWings
Abdomen:
Photo ® Van Waters & Rogers /
Reproductive organs
Digestive tract
Defensive glands
Communication glands
Insect exoskeleton
Photo ® Van Waters & Rogers /
Made of chitinous proteins strong resilient ideal for small organisms
Covered with wax layers for waterproofing
Pesticides designed to affect insect skeletal systems:
Diatomaceous earthAbrades insect cuticles
Silica aerogelsAbsorbs waxes from
exoskeleton
Note: Dessicants only really effective in dry environments.
Insect respiratory system
Simple series of tubes and openingsSpiracles Tracheae
Respiratory system
Photo ® Van Waters & Rogers /
Spiracle
Trachea
Horticultural oil Vegetable oils
Mineral oils
armored scales
mosquito larva
Oil: An insecticide for all spiracles How insects grow and develop Molting occurs during immature stages Stages between molts called “instars”
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Cicada nymph final molt
Courtesy USDA ARS image gallery
Metamorphosis: (<Greek) a change in form
No metamorphosis in two groups: springtails and silverfish
Gradual * metamorphosis: grasshoppers, termites, thrips, dragonflies
Complete metamorphosis: beetles, butterflies and moths, flies, bees and wasps, ants, fleas
Gradual metamorphosis
Photo ® Van Waters & Rogers /
Three life stages: egg, nymph, adult
Immatures called “nymphs” share a resemblance to the adult
Wing-pads develop externally
Gradual metamorphosis
Photos ® Van Waters & Rogers /
Egg
Nymph
Adult
Complete metamorphosis
Most advanced form of development
Four life stages: egg, larva, pupa, adult
Immature form called “larva”
Wings develop internally in larvae
Complete metamorphosis
Photos ® Van Waters & Rogers /
Eggs
Larvae
Adult
Pupa
Types of mouthparts
Chewingcrickets, termites, beetles,
caterpillars Piercing/suckingplant bugs, fleas, lice, mites,
hoppers Spongingsome flies
Siphoningmoths and butterflies
Chewing mouthparts
Side to side movementUpper lip: labrumJaws: mandibles,
maxillaeTongue: hypopharnyxLower lip: labium
Chewing, boring, mining damage possible
Piercing/sucking mouthparts
Microscopic food channel for liquids
Plant wilting, honeydew, disease transmission possible
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Usually folded under body, between legs
Milkweed bug, Oncopeltus fasciatus
Piercing sucking mouthparts Sponging mouthparts
Sponge-like labella on certain flies
Capable of feeding only on exposed liquids such as nectar or sap
Capable of transmitting pathogens in the house fly & blow fly
Siphoning mouthparts
Flexible maxillae form soda-straw like mouthparts
Incapable of piercing skin or plant surfaces.
How insects are classified and named
Carl Linnaeus (Carolus Linnaeus) 1707-1778
Father of taxonomy, born in Sweden
Professor, Uppsala University developed today’s system of
scientific names Species Plantarum (1753), Genera
Plantarum (1754) and SystemaNaturae (1758) standard reference for naming plants and animals
Linnaeus’ created a taxonomy
*added later by Latrielle
(> Greek: taxa=to arrange, classify or place)Memory aide
King Philip Came Over From Gloria Spain
Kingdom, Phylum, Class, Order, Family, Genus, Species
A word about scientific names..Blatella germanica (Linnaeaus)Genus species Author
Common names:croton bug (NY)German cockroach (U.S.)steamfly (U.S.)waterbug (U.S.)cucaracha (Spanish)küchenschabe (German)*&#@$!!* (universal)
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Wild and crazy namesTropical canopy-inhabiting beetles by Terry
IrwinAgra vationAgra cadabraAgra katewinslettae (ESA Newsl. 9/2005)
Hemipteran genera described by G. W. Kirkaldy in 1904Ochisme (sounds like O kiss me)PolychismePeggichismeDolichisme, etc. (Berenbaum 1993)
Wild and crazy names Tiphiid wasp described by V.S.L. Pate in 1947 Lalapa lusa (op. cit.)
Liparid fly named by B. Neumoegen in honor of colleague H.G. Dyar in 1893 dyaria (op. cit.)
Three species of slime mold beetles named by Q. Wheeler and K. Miller in 2005 Agathidium bushi Agathidium cheneyi Agathidium rumsfeldi (ESA Newsl. May 2005, Bull. Am. Mus.
Nat. Hist. 291 (1), 1-167)
Lots more at: http://home.earthlink.net/~misaak/taxonomy/taxPuns.html
How to classify?
Insect Orders 30 total, 5 “Big Orders” Archaeognatha (bristletails) Thysanura (silverfish) Ephemeroptera (mayflies) Odonata (dragonflies) Plecoptera (stoneflies) Isoptera (termites) Blattodea (cockroaches) Mantodea (mantids) Grylloblattodea (ice crawlers) Mantophasmatodea Orthoptera (grasshoppers) Phasmatodea (walking sticks) Embiidina (webspinners) Dermaptera (earwigs) Zoraptera
• Psocoptera (booklice)• Phthiraptera (lice)• Thysanoptera (thrips)• Hemiptera (bugs, aphids, etc)
Holometabolous orders• Megaloptera, Raphidioptera,
Neuroptera• Coleoptera (beetles)• Strepsiptera• Mecoptera (scorpionflies)• Siphonaptera (fleas)• Diptera (true flies)• Hymenoptera (bees, wasps, ants)• Tricoptera (caddisflies)• Lepidoptera (moths, butterflies)
Ptera = Latin for wings
Order Hemiptera Name: Hemi- half,
ptera=wing
Metamorphosis: gradual
Mouthparts: piercing/sucking
Two large suborders
Suborder Homoptera: Cicadas and their relatives
Name: homo = same, ptera = winged
Food: plant feeders
Notes:Wings uniformly membranous, held roof-like over the body. Aphids, whiteflies, leafhoppers, scales
Homoptera: mealybugs,aphids, leafhoppers, scales
Suborder Heteroptera: true bugs
Name: heteros Gr.= different, ptera = winged
Metamorphosis: gradual
Mouthparts:piercing/sucking
Food: plant feeders, predators
Heteroptera: True bugs
Only outer half of wings membranous, held flat over the body. Stink bugs, plant bugs, assassin bugs, leaf-footed bugs, etc.
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Coleoptera: Beetles
Name: Coleo = sheath, ptera = winged
Metamorphosis: completeMouthparts: chewingNotes: Only 2nd pair of wings used in
flight. Most diverse insect order. Many important pests of outdoor plants, stored grains and wood.
Beetle takingflight
First pair of wings is the elytra
Diptera: Flies
Name: di = two, ptera = winged
Metamorphosis: complete
Mouthparts: sponging, piercing/sucking
Notes: Excellent fliers. Larvae are legless and generally found in water or around wet environments. Many important indoor and outdoor pests.
Diptera: Flies
Diptera larvae
Legless and generally found in water or around wet environments.
Lepidoptera: moths and butterflies
Name: lepido = scale, ptera = winged
Metamorphosis: completeMouthparts: siphoningNotes: Scaly wings, often colorful. Some
important pests of fabric, stored products.Texas Cooperative Extension
Lepidoptera
Immature form: caterpillar
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Hymenoptera: Bees, wasps and ants
Name: humen = membrane, pteron = wing
Metamorphosis: complete
Mouthparts: usually chewing
Notes: Abdomen and thorax joined by narrow waist. Many social.
Texas Cooperative Extension
bees
parasitic wasps
ants
aculeate wasps Texas Cooperative Extension
Other notable Orders…
Collembola: springtails
Odonata: dragonflies
Orthoptera: Grasshoppers
Mantodea: mantids
Isoptera: termites
Isoptera: fleas
Every July, the fleas would test their endurance in the grueling Tour de Frank.
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Master Gardener TrainingMichael E. Merchant, PhD, BCE
m-merchant@tamu.edu
©2004 Texas Cooperative Extension
Problems with insecticides
Heavy use resulted in resistance
Toxic to non-target organisms
Secondary pest problems
Integrated Pest management
IPM - a strategy that focuses on long-term suppression of
pests uses a combination of control tactics minimizes pesticides’ negative impact
on people and the environment strives to be economical
The IPM pyramidPesticides
Biological controls
Physical / Mechanical
controls
Cultural / Sanitation Practices
Non-chemical controls for pests
cultural
mechanical
biological
Pesticides What are pesticides? Any substance or mixture of
substances used for controlling, preventing, destroying, repelling, or mitigating pests. insecticides, herbicides, fungicides,
bactericides, repellents, attractants
Pesticide modes of action
Nervous system poisons Metabolic inhibitors Hormone mimics Physical poisons Repellents Attractants
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Not all pesticides are equally hazardous!
How safe is this pesticide?Everyone wants to know
The dose makes the poison
Paracelsus (1493-1541) “All substances are poisons; there is none
which is not a poison. The right dose differentiates a poison and a remedy.”
Dose-Response Curve Dose-Response Curve
Some terms
LD50 (Lethal Dose 50) - The amount of material needed to kill half of a test population
Mg/Kg – The amount of toxin (in milligrams) per Kilogram of body weight of the test subject (equals parts per million)
EPA Pesticide Toxicity Classes
Pesticide Safety
Acute toxicityRapidly produced toxicity, usually resulting from a single exposure
Chronic toxicityToxicity due to slow-action or long-term exposure to a poison
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Pesticide Safety
Possible chronic effects:Carcinogenicity-cancer
Mutagenicity-genetic mutation
Teratogenicity-birth defect
Oncogenicity-tumors
Reproductive effects
Delayed neurological effects
Tests required to register a pesticide
Acute oral toxicity Acute dermal toxicity Acute inhalation Acute intraperitoneal Eye irritation Dermal irritation Dermal photosensitization Acute delayed neurotoxicity 90-day rat feeding study 12-month dog feeding study
21 & 90-day dermal Lifetime rat feeding study Lifetime mouse feeding
study Teratology (rat) Teratology (rabbit) Reproduction Excretion/metabolism &
accumulation Antidote Mutagenicity
It is impossible to provide experimental evidence that
anything is ABSOLUTELY safe!
Toxicity x Exposure = Hazard
Pesticide labeling Pesticide labeling
Most important source of information The label is the Law Read the label
before you buy/sell the product before you use the product before you dispose of the product
Common vs. trade names Trade name is a
proprietary name used by a company (e.g., Sevin®)
Common name is the generic name for the pesticide (e.g., carbaryl)
Extension publications use common names
The public looks for trade names : (
Pesticide formulations
Granules Baits Dusts Liquid concentrates Aerosols Suspensions RTU (ready to use)
Insecticide chemical classes
Organo-phosphates Carbamates Botanicals Pyrethroids Neo-nicotinoids Others
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Organophosphates
Many common pesticides chlorpyrifos (Dursban) diazinon acephate (Orthene) malathion
Disappearing from market
Botanicals
Pesticides derived from plants pyrethrins neem extracts & oils rotenone Mint oils citrus oils clove oil other essential oils
Pyrethrins
From ground-up flowerheads of pyrethrum daisies
A natural combination of six compounds: pyrethrins I and II, jasmolin I and II, and cinerinI and II
More uses approved than any other insecticide Usually includes a “synergist” to keep insects
from detoxifying it
Chrysanthemum cinerariifoliumC. coccineum
Spring cankerworm
Pyrethroids Synthetic chemicals based
on study of pyrethrinschemistry
Broad spectrum replacements for Dursban®, diazinon
Residual and stomach poisons
Low in toxicity to birdsand mammals, but hazardous to fish
University of Florida
Pyrethroids
Recognize by suffixes: -thrin or –ate
Examples: Esfenvalerate Permethrin Bifenthrin Cyfluthrin Allethrin Sumithrin Others
Neonicotinoids
New class of systemic pesticides imidacloprid (Bayer) dinotefuran (Spectracide?)
Effective against Homoptera Coleoptera (chewing, boring) Thysanoptera
Relatively low in mammalian, bird toxicity
Organic vs. synthetic
“organic” pesticides include products derived from natural sources
Synthetic pesticides are human-produced
Poison ivy
Are organic products inherently safe?
Giant hogweed
Plants also have carcinogens!
Tobacco (leaf) - 7 carcinogens Strawberry (fruit) - 7 carcinogens Onion (bulb) - 6 carcinogens Tea (leaf) - 6 carcinogens Carrot (root) - 6 chemicals Cauliflower (leaf) - 5 chemicals Grapefruit (fruit) - 5 chemicals
Source: Phytochemical Database, USDA - ARS - NGRL http://www.ars-grin.gov/duke/activity.html
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Low impact pesticides
Pesticides with minimal impact on people and on beneficial organisms, including beneficial insects
Low impact pesticides
Insecticidal soaps & oils Kill small and soft-bodied
insects and mites. Contact insecticide with short residue.
Examples: Safer’s soap, Sunspray Ultrafine Spray Oil, vegetable and neem oils
Low impact pesticides
Microbe-derived Consisting of, or derived from microbes. The
best are low in toxicity to humans and non-pathogenic to non-target organisms.
– Examples: Bacillus thuringiensisproducts, spinosad
Low impact pesticides Baits
Mixture of an insecticide with some sort of food attractive to pest. Generally low percentage active ingredients make these relatively safe.
Examples: fire ant baits, containerized cockroach baits, granular ant, cockroach and cricket baits
Low impact pesticides Botanicals
Derived from plants. Although some active ingredients are toxic, generally formulated as a low percentage a.i. and degrade quickly in the environment.
Examples: pyrethrum, rotenone, neem extract, mint oils, capsacin, others...
Low impact pesticides Insect growth regulators
Based on insect hormones unique to arthropods
Disrupts reproduction, molting, other growth processes
Excellent safety record Products for fire ants,
white grubs, fleas, others
Low impact pesticides Other low toxicity
pesticides Kill through physical or
stomach poison action. Generally non-toxic on skin. Examples: silica aerogel,
diatomaceous earth, boric acid and borate compounds, sulfur
Parts of a Label
Trade name Chemical name Common name Formulation type Allowed sites
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Parts of a Label
Precautionary statement
First aid Environmental
statement EPA Registration
number Directions for use Disposal instructions
Leeway with labels?
Very little Can use on pests not
listed only if the site of application is listed
In most cases you can use LOWER rate than on the label
Pesticide signal words
Caution LD50 greater than
500 mg/Kg Warning
LD50 50-500 mg/Kg Danger - Poison
LD50 less than 50 mg/Kg
1
Master Gardener Entomology TrainingMichael E. Merchant, PhD, BCE
m-merchant@tamu.edu
Copyright Texas AgriLife Extension
Common Texas pests
Different types of insect damage Chewing
Mining Skeletonizing leaf feeding root feeding Boring
Sucking Meristem feeding Phloem feeding Mesophyll feeding
Gall making
Chewing insects
Tobacco budworm on petunia
Root feeding by Pyllophaga
Leaf skeletonizing by oak sawfly
Chewing pests Caterpillars
sawflies
beetles
grasshoppers
snails and slugs
Fall webworm/tent caterpillar
East
ern
tent
cat
erpi
llar
Fall
web
wor
m
Fall webworm Physical removal of webs,
larvae on smaller trees
Insecticides
Adult fall webworm
Chemical caterpillar control
Texas Cooperative Extension
soaps and oils
Bacillus thuringiensis
Spinosad Fertilome® Borer, Bagworm,
Leafminer & Tent Caterpillar Spray
Greenlight® Spinosad
pyrethroids
20/40 Rule for defoliators 20% spring
defoliation
40% summer defoliation before tree health is affected
Bagworm
Life spent in silken cocoon
Females wingless
One generation/year
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Bagworm
hand removal
Bt, spinosad
Pyrethroidinsecticides work well
Bagworm damaged tree
Photo courtesy Neil Sperry
What would you do?
Fall caterpillars
Damage usually not important to tree health
Spray tree with low impact pesticide for aesthetic purposes Treat tree with hose-end
sprayer or hire arborist for large trees
Walnut caterpillar on pecan
Leaf rollers and tiers Caterpillars specializing on various plants
Leaf roller on redbud
Leaf rollers and tiers Difficult to control
with insecticides
Early treatment best
Systemic insecticidesOrthene
Lesser canna leafroller
Fate of 3 types of insecticides
Contacts kill only through direct contact (you get what you hit!), otherwise they evaporate Soap, oils
Residuals remain on plant surfaces for varying times malathion, carbaryl (Sevin), diazinon, cyfluthrin (Bayer
Advanced Garden), permethrin (Spectracide Pro)…
Systemics absorbed by, and work from inside plant acephate (Orthene), imidacloprid (Merit), dinotefuran
(Safari)
Sawflies
Caterpillar-like Not susceptible to Bt,
spinosad Identification Single eyeFive or more pairs of
prolegs on abdomen
Loblolly pine sawfly
Snails and slugs Sanitation
Traps
Barriers
Baits metaldehyde iron phosphate
Grasshoppers Periodic outbreaks in rural
and urban fringe areas
Row covers
Insecticides permethrin (Conquest,
Spectracide) cyfluthrin (Bayer) bifenthrin (Ortho) esfenvalerate
Beetles
Texas Cooperative Extension
Residual insecticides work well
Flea beetles on crape myrtleCucumber beetle
3
White grubs Immature form of the June
beetle
Underground root feeder 5-10 grubs per ft2
One generation per year Adult emergence in June,
July Ideal treatment time around
4th of July (July-early August)
White grub controls for homeowners
Granular insecticides imidacloprid + cyfluthrin (Bayer Advanced
Lawn® Complete Insect Killer) halofenozide (Scott’s GrubEx - old) Trichlorfon (Dylox®, Bayer Advanced Lawn
24-Hour Grub Killer Plus) chlorantraniliprole (Scott’s GrubEx)
Water-in with at least 1/2 inch water after application.
Sap-feeding insects
Brown soft scale
Aphid
Phloem feeders
Feed on the phloem (sap) of plantsAphidsWhiteflies Plant bugs ScalesMealybugs
Aphids
Pear-shaped
Long legs
Tiny tails (cornicles)
Found in colonies
Diagnosing aphids
Pear-shaped insects on leaves, stems (with or without wings) Cast skins Honeydew deposits
Honeydew
Crepe myrtle aphid and black sooty mold
Scale-caused black sooty mold
Aphids High reproductive rate Parthenogenesis (able to
reproduce without mating)
Damage plants via feeding, honeydew, disease transmission
Subject to many natural enemies
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Aphid natural enemies
Syrphid fly
Lady beetle
Green Lacewing
Aphid natural enemies-immature forms
Lacewing larva
Lady beetle larva
Syrphid fly larva lady beetle pupae
Bev Wigney, magickcanoe.com
New Mexico State University, http://www.nmsu.edu/biocontrol/bugs/
Healthy aphids
Parasitized aphid An aphid’s worst nightmare: parasitoidsEmerging parasitoid
Aphid mummies
Parasitoid stinging aphid
Aphid control
protect natural controls
water streams
soaps and oils
pyrethrins
systemics
organo-phosphates
USDA
Whiteflies Nymphs are sap
feeders on leaf undersides
Adults small, whitish flying insects
High reproductive rate
Often difficult to control
Adult whitefly
Whitefly control Soaps and oils
good coverage essential
Pyrethrins/neem Systemic insecticides
acephate (Orthene) imidacloprid
Multiple treatments may be needed on 7-10 day cycle
May be a secondary pest
Scale insects Euonymous scale
Brown soft scale
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Scale insect control
Soaps and oils dormant vs. summer oils
systemic insecticides
sprays timed to kill crawler stage
Scale crawlers
Crape myrtle bark scale
New pest on crape myrtle
dark trunks, leaves (black sooty mold)
dinotefuran, imidacloprid
Thrips Very tiny most commonly eaten
insect
Feed on meristemtissue
Damage: delay in growth darkening of flowers puckering and stunting
Thrips damage on chrysanthemum, U of Kentucky
Thrips control Systemic
insecticides acephate (Orthene)Disulfoton
Spinosad Treat before damage
becomes severeGreenhouse thrips
Mesophyll feeders Spider mites Lace bugs
Leafhoppers
Other plant bugs
Spider mites Fast reproductive rate
Live on leaf undersides
Favored under hot, dry conditions
Can be worsened by some insecticides permethrin imidacloprid
From w
ww.plantlilies.com
Spider mite control
Water streams Soaps and oils
pyrethrins
sulfur
bifenthrin
Lace bugs
lantana lace bug
http://ww
w.cedarcreek.um
n.eduD
r. John Haarstad
Corythuca
arcuata
Borers Enter as larvae through
weak spots in bark Adult forms emerge from
holes chewed in bark One generation per year,
usually
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Borer damage
Adult borers
University of Colorado
Borers Good horticultural
practices can prevent many kinds
Avoid wounding, damage to bark
Residual insecticides: permethrin cyfluthrin
Galls Plant response to a
stimulus or injury
Galls formed when tissue is growing
Most plants are not hurt by galls
No effective sprays for galls that have formed
Galls caused by wasps
Fire ants, Solenopsis invicta Exotic pests from South
America
Range from 40 to 400 mounds per acre
In addition to nuisance, can be economically, medically important
Fire ant mounds
Step 1: Let them eat bait
Broadcast a fire ant bait over the entire yard
Use a seed spreader to ensure uniform coverage
Secrets to success with baits
Apply only fresh baitscheck date of
manufacture test some first
Apply when rain is not expected
Apply when ants are active
Check date of manufacture or test first
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When are fire ants active? When soil surface
temperatures are between 70° and 95° FMay - September in
most areasEvenings during hot
weather
Fire ant bait products Amdro AmdroYard
Treatment Amdro Ant Block Conserve Once and Done Extinguish Extinguish Plus Distance Maxforce
How often should baits be applied? Every 8 weeks, or as
needed hydramethylnon (Amdro ®) spinosad (Eliminator ®)
Once or twice a year methoprene (Extinguish ®) pyriproxifen (Spectracide ®,
Distance ®) hydramethylnon+methopren
e (Amdro® Firestrike Fire Ant Bait)
Step 2: Treat the mounds
Treat problemmounds with an individual mound treatment
Not all mounds need to be treated
Individual mound treatments
Liquid concentrates and Ready-to-use liquids
Granular insecticides
Dusts
Aerosols
“Organic formulations”
Secrets to success with mound treatments
Use 1 to 2 gallons of water per mound when using liquids, granules and some dusts
Don’t disturb the mound unnecessarily
Insects in the City
Insect F@ctSheets
http://citybugs.tamu.eduUseful Internet Sites Http://insects.tamu.edu
AgriLife Extension Bookstore http://agrilifebookstore.org
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http://bugguide.netThe End
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