Thrips

Info for the Indoor Gardener

Wondering what to do if your houseplants are attacked by thrips? Below the Google ads the Indoor Gardener can learn how to identify and eradicate these common garden pests.

DESCRIPTION

thrips are alligator shape: long and narrow
very tiny: 1/16th - 1/8th inch
some sources say as small as 1/25th inch
most have wings
fringes on wings
short antennae
females usually larger than males

LOCATION

hide in buds of flowering houseplants
they like dark parts of the plants
attracted to water and moisture
favorite houseplants:

arrowhead vine
dieffenbachia
ficus
hibiscus
mother-in-law's tongue
philodendron
schefflera
zebra plant
Franliniella occidentalis prefers African violets

MULTIPLICATION

fly to nearby house plants
can be blown by fan, wind
also spread by crawling, jumping
up to 8 generations/year

DESTRUCTION

puncture plant
suck nutrition from leaves, sometimes stems
slows growth
can transmit fungal and viral plant diseases
sources disagree whether or not species of this garden pest are plant-specific
sting people and pets: can cause itching or rash

DETECTION

very hard to find
use a magnifying glass
shake branches over white paper to detect
use yellow or blue sticky traps
they can be found hopping along the soil surface
leaves appear misshapen or curled
brown edges at times
scarring on leaves
leaf can appear with stripes or spotting
upper layer of leaf can be dead
silver or white scarring present
black feces spot present
leaf may become lacelike
flower petals have spots that are pale or dark
leaves drop off

SOLUTION

Since some species of these garden pests are beneficial, be sure to identify your thrips before trying to control them.

isolate plant immediately, moving it slowly away from other houseplants
use systemic insecticides
chemical sprays: Acephtate, Malathion, Diazinon, Carbayl, Methoxychlor (follow directions)
some sources advise against Malathion use as not effective and encourages increase in spider mites
horticultural oils: azadriachtin, neem oil, permethrins with piperonyl butoxide
insecticidal soaps
garlic oil
every 2-3 days mist infected plants or gently wash off - repeat for at least 4 weeks
foliar pesticides - every 5-days
mist with a drop of pine oil in water
cut off branches where thrips are detected
use dichlorvos strip and cover plant with plastic bag for 24 hours
Natural Predators for use in greenhouse or conservatory:

Megaphragma mymaripenne
Thripobius semiluteus - parasitic wasp
Orius insidiosus - pirate bugs
Amblyseius cucumeris - predator mite
Neoseiulus mackanziei - predator mite
Iphiseius degenerans - predator mite
Hypoasis miles - predator mite
Chrysoperla - green lacewings
Damsel bugs

For Botanists, Scientists, Outdoor Gardeners, and School Reports

Not all thrips are garden pests. Black hunter and six-spotted thrips are beneficial, feeding on fungal spores or pollen. Some species eat up pest thrips as well as spider mites

Order: Thysanoptera
Suborders:

Terbrantia
Tubulifera

worldwide about 5,000-6,000 species
U.S. and Canada - about 265 species (not counting predator thrips)
100s of varieties
Beneficial Species:

Franklinopthrips orizabensis
Franklinopthrips vespiformis

LIFE CYCLE:

Females do not need to mate to lay eggs
Unfertilized females lay only male eggs
Mated females lay eggs of both genders
Female "ovipositors" cut slits in leaves or buds
25-50 eggs are laid in these channels
Eggs are narrow, long, large
Eggs hatch in 2 days - 1 week
Two nymph stages in which they feed (lasts about 1 week)
Larvae are wingless
Prepupae and pupae stages fall off leaves and grow in soil
Prepupae stage about 1-2 days
Pupal stage is non-feeding; not true pupal stage (lasts 1-3 days)
About 8 generations/year
Egg to adult - about 2 weeks (depends on moisture and temperature; can take up to 3 weeks)
Adults live 1 - 1-1/2 months

DISCLAIMER: The Indoor-Gardener.com provides information through data research and personal experience and does not mean to recommend or refute any product used for insect control inside or outside the house. Read and follow instructions carefully as listed on all products. Indoor-Gardener.com is not responsible for use of any product or method described on these pages, nor for any possible adverse affects of such use. The legal use of chemicals for plant health can change, and it is solely the responsibility of the user of such chemicals to remain in compliance with such laws. Indoor-Gardener.com and Batya D. Wininger assume no liability resulting from the use of any information on these pages. While this website does its best to provide only the best, up-to-date information to its visitors, there can be changes and mistakes. Read labels carefully and follow instructions for use.

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