THE LEAFLET

Pest Management  |  August 14, 2020

The Houseplant Pest Cheatsheet



Pests can be the bane of any houseplant enthusiast’s passion. The good news is, when caught and identified early they are eminently treatable. Use our handy cheat sheet to bring yourself up to speed on the most common types of houseplant pests. 


Pest

Physical Description

Life Cycle

Feeding

Habitat

Highly Susceptible Plants

How to treat aphids on indoor houseplants

APHIDS

Small, sap-sucking pests with pear-shaped, unarmored bodies; species range from yellow, green, black, brown, to pink. Wingless adults and female nymphs are most common in interior spaces, though winged forms may emerge from overcrowded colonies.

Eggs hatch in the spring, producing a wingless female that will parthenogenetically reproduce more wingless females. Aphids may develop wings once the host plant has perished, allowing them to locate a new host with ease.

Use piercing, sucking mouthparts to feed on plant sap. Because aphids require more protein than they’re able to extract from plant tissues, they will excrete the excess sugars that they suck from the plant. Can transmit viral diseases.

Found on undersides of developing leaves and on new buds.

  • Herbs
  • Annuals grown indoors
  • Flowering plants

Management

  • Neem Oil / Azadirachtin A&B
  • Insecticidal soap
  • Mineral oil
How to treat spider mites

SPIDER MITES
read the guide

Have oval shaped bodies and their possible colors range from red through yellow to green.

The body of a spider mite is separated into two distinct parts: (1) the gnathosoma and (2) the idiosoma. The gnathosoma includes only the mouthparts. The idiosoma is the remainder of the body and parallels the head, thorax and abdomen of insects.

The eggs are attached to fine silk webbing and hatch in approximately 3 days. The life cycle is composed of the egg, the larva, two nymphal stages, and the adult. The length of time from egg to adult varies greatly depending on temperature. Under optimum conditions (~80ºF), spider mites complete their development in 5 to 20 days. There are many overlapping generations per year. The adult female lives 2 to 4 weeks and is capable of laying several hundred eggs during her life.

Feeds by piercing plant surfaces with the needle like mouthpart, subsequently sucking out the plant’s cellular contents. This leaves a grayish or yellowish stippled appearance on the foliage and causes distortion, dried out foliage, and leaf drop. 

Found on undersides of newly developed leaves. 

Webs may be visible on any part of the plant during heavy infestations.

As their populations rapidly expand and competition for food increases, mites will congregate at the apex of the plant and produce web-like silk glands on which individual mites travel.

  • Calathea, Maranta spp.
    • Ficus spp.
    • Palms
  • Fatsia japonica
  • Bird of Paradise
  • Natal Mahogany
  • Ivy spp.

Management

  • Insecticidal Soap
  • Neem Oil / Azadirachtin A&B
  • Spinosad
How to treat mealybugs

Oval shaped, often covered by a waxy, filamentous, white, cotton-like material


Vary in length from ⅛ inch to ⅕ inch; soil mealybugs are sometimes found on plant roots, with their appearance and feeding habits similar to those of the foliar type. 

Long tailed type gives birth to living nymphs, while secretions from the short-tailed type produce an egg mass containing from 100-300 eggs; eggs hatch into immature crawlers within 14 days, while nymphs generally require 6-8 weeks to mature, but can do so in as little as 18 days at high temperatures. 

Extraction of plant sap results in discoloration, stunting, and possible death of the plant. Control is difficult, as even some pesticides may not penetrate the waxy, cotton-like covering of these dense insect colonies. 

Found at stem nodes, in leaf axils, and in undersides of leaves along the veins. 

  • Aglaonema spp.
  • Epipremnum spp.
  • Dracaena spp.

Management


  • Neem Oil / Azadirachtin A&B
  • Insecticidal Soap
  • 50% Rubbing Alcohol
How to treat scale

Two main groups exist: armored or hard scales; and unarmored or soft scales 


The names refer to the shell-like coverings which protect the insect body. Control, as with mealybug, is hindered by the protective scale covering the insect. 


Scales measure up to ⅛ inch long and can be round, oval, or oyster shell-shaped, predominantly brown in color but can range from white to black. 

Females may produce hundreds of eggs beneath the scale; eggs later hatch into tiny translucent crawlers about 1/100-inch long; these unprotected crawlers migrate to new feeding sites where they become attached to the plant and develop their own protective shells. 

Removal of plant sap causes yellowing and wilting of foliage. 
Hard scales produce very little honeydew. Dead scales look dry and puckered and are easily dislodged. 

Found along leaf veins or on stems.

  • Schefflera spp.
  • Ficus spp.
  • Natal Mahogany
  • Succulents

Management

  • Imidacloprid
  • Mineral Oil
  • Neem Oil
  • 50% Rubbing Alcohol
How to treat scale

Tiny, elongated insects with tan, brown, or black bodies that vary between 0.5mm-5mm in length. Adults have bristle-like wings.

Eggs hatch into larvae, which may pupate in the soil or on the host plant. The full life cycle may take 2-4 weeks, with high temperatures favoring quick development.

Both adults and larvae have piercing and rasping mouthparts with which they injure plant tissues in order to extract sap. Injured tissue may have a silvery, stippled appearance and may later turn brown via the loss of sap.

Found inside of new growth / unfurling leaves,  and on flower buds.

  • Philodendron spp.
  • Monstera spp.
  • Syngonium spp.

Management

  • Spinosad
  • Insecticidal Soap
  • Neem Oil / Azadirachtin A&B
How to treat fungus gnats

FUNGUS GNATS
read the guide

Adult is a grayish fly about 1/8 -inch long; a weak flier, they possess a delicate pair of wings and long legs. 

The long, thin soil-inhabiting larvae are translucent white with a black head and attain a length of about ¼ inch. 

Adult females deposit 75-200 eggs in moist, organically rich soil; the full life cycle includes several pupal stages and can be completed in 4 weeks, which is shorter in higher temperatures. 

Larvae feed in and on wet soil. Larvae feed mostly on decaying plant tissue, but may also feed on the stem at the soil line and on the roots, stripping them of their outer layers of tissue; this allows fungal rot organisms to enter. 

Adult flies are found around near moist soil surface. Larvae are found on or within the soil.

  • Plants that do not want to dry completely between watering
  • Planters with reservoirs

Management

  • Bacillus thuringiensis
  • Let soil dry out (if possible)
How to treat caterpillars on indoor houseplants

CATERPILLARS

The caterpillar is the worm-like larval stage of butterflies and moths. 

When the egg hatches, the caterpillar will start his work and eat the leaf it was born onto. Thus, the mother butterfly needs to lay her eggs on the type of leaf the caterpillar will eat – each caterpillar type likes only certain types of leaves. Since they are tiny and can not travel to a new plant, the caterpillar needs to hatch on the kind of leaf it wants to eat. 

In addition to creating notches and holes from feeding, caterpillars generally leave black fecal deposits on plants. 

Can infest nearly all parts of the plant, and some can even be found in the growing media or underneath pots. 

  • Herbs
  • Annuals grown indoors
  • Flowering plants

Management

  • Manual removal. You can tell how many of them you have on a plant by how much of their poop (black dots) is distributed on the foliage!
How to treat millipedes on indoor houseplants

CENTIPEDES & MILLIPEDES

Centipedes are elongated metameric creatures with one pair of legs per body segment. Most centipedes are generally venomous and could inflict a painful bite, injecting their venom through pincer-like appendage known as forcipules. Despite the name, centipedes can have a varying number of legs, ranging from 30 to 354. Centipedes always have an odd number of pairs of legs. Centipedes are predominantly carnivorous.

Centipedes mate in warm months and stay dormant through winter. A centipede may live up to six years.   

Centipedes are usually attracted to houseplants because of an abundance of organic material -- such as fallen leaves -- and moisture. 

Centipedes feed on home-invading species like cockroaches and spiders.

Centipedes neither feed on, nor damage plants.

Centipedes may find their ways into your indoor plants while looking for insects to feed on.

The warmth and safety of a heated home may also attract centipedes inside to reproduce.

  • Any

Management

  • Diatomaceous earth