Indoor Garden Pests: Lifestyles Of The Creepy And Crawly

Indoor Garden Pests: Lifestyles Of The Creepy And Crawly

Bugs are kind of like "The Transformers" alien-robots that star in the popular sci-fi movies. They change so dramatically, you may not even realize when they have gone from innocuous to destructive. Insects' feeding habits, hiding places, and even appearance are so different as they grow and mature that you almost wouldn't think they were the same species. To keep a few pests from turning into a major infestation, you need to recognize them at each stage and treat them with a pest control that's effective against each type. Here are the six most prevalent grow room pests and how to identify them – from eggs to adults.


  • Whiteflies Eggs: Clusters of up to 400 eggs are deposited in a circular pattern on the underside of leaves, most commonly on the uppermost branches of plants. The eggs are pale yellow when freshly laid. They then darken to brown when they're close to hatching, which typically takes a week to 10 days.
  • Nymphs: The newly hatched pests are pale, almost translucent, so they blend with the color of the leaves to which they are attached. The youngest (first instar or stage) nymphs are called "crawlers" because they move away from the egg before flattening themselves against the leaves to feed. They remain in place and continue sucking juices from plants as they grow and shed their outer shell, or molt, three more times.White Fly Larvea
  • Adults: After molting for the fourth time, whiteflies turn into a pupa (like caterpillars in a cocoon) and stop feeding for a week. They emerge as adults with wings, ready to fly to new plants and lay their eggs. The whole process from egg to adult takes about 25 days and the cycle can repeat almost constantly in a warm, indoor garden.
  • Controls:

A. Set up sticky traps to help you monitor for the presence of adult whiteflies and control small populations of them.

B. Spray neem oil on egg clusters before they hatch.

C. Treat the destructive nymphs with potassium salts of fatty acids (insecticidal soap), which breaks down their protective outer coating and causes them to dehydrate.


  • Aphids Eggs: In an indoor garden, most types of aphids bear live young – as many as 80 in a week – but those that do lay eggs, which are nearly translucent and almost microscopic, tend to deposit them on browning leaves and rotting foliage.
  • Nymphs: The pale, tiny wingless nymphs begin feeding on plant juices immediately, rapidly increasing in size and molting up to four times before becoming adults.
  • Adults: Mature aphids are wingless until the population becomes too dense to feed on just one plant. At that point, some of the females develop wings and fly off to start new colonies on other host plants. In the warm confines of indoor gardens, aphids can produce many overlapping generations each year, developing from newly born nymph to reproducing adult in as little as a week. That's how an aphid population can expand dramatically before you've even noticed them.  Aphid Nymphs
  • Controls:

A. Aphids often hide in the nooks and crannies of plants, so the best way to eliminate them is to coat the whole plant with a spray that combines neem oil, which suffocates both nymphs and adults, and insecticidal soap, which dehydrates them.

B. Be sure you get the spray into all of the hard-to-reach places, such as between branches and stems.


  • Thrip and LarveaEggs: The long cylindrical or kidney-shaped, pale white eggs look like tiny grains of rice. They're inserted into leaves, stems, or flowers. The females do not need to mate for reproduction and each female can produce up to 80 eggs, which hatch within days.
  • Nymphs: They are wingless and translucent when they emerge and they begin feeding on plant sap immediately. The nymphs molt two or more times, often becoming darker in color with each stage, until they drop into the soil or growing medium to pupate, developing wings and the rest of their adult bodies.
  • Adults: After emerging from the soil, the black or brown adults fly to a host plant and prepare to deposit their eggs. The whole life cycle is about two weeks long. Thrips live year-round inside.
  • Controls:

A. Spray plants with a formula that includes azadirachtin, a natural insect growth regulator extracted from seeds of the neem tree, which disrupts the hormones that cause nymphs to molt. This eliminates individuals before they can transform into reproducing adults.


  • Spider MiteEggs: The adult pests are so tiny they're very hard to see, so you can imagine that their round, translucent eggs (which look like tiny water droplets) are not visible without magnification. A female lays as many as 300 eggs over a couple of weeks on the leaves and stems of host plants.
  • Nymphs: Tiny six-legged larvae hatch and begin sucking plant sap, most often on the underside of leaves and in other unseen places. After a few days, the nymphs molt and grow two more legs. They molt twice more before maturing into adulthood.
  • Adults: After mature spider mites mate, they no longer feed on the plant, but they do spin white webbing around leaves and stems. Indoors, the whole life cycle can occur in just five days.Spider Mite Web
  • Controls:

A. Spider mites thrive in very hot, dry environments, so maintaining the humidity level of your grow room between 50 and 60 percent can help prevent them from reaching infestation levels.

B. If a growing spider mite population has become a problem, spray them with a combination of insecticidal soap and pyrethrins, a compound derived from chrysanthemum flowers, to kill adults and nymphs on contact. Treat leaves with neem oil to destroy any eggs left on them.


  • Fungus GnatEggs: As you might guess from their name, these pests typically lay their clusters of round, whitish-yellow eggs in patches of fungus on the surface of growing media, on leaves, and in other damp, dark areas of indoor gardens.
  • Nymphs: The eggs hatch in about five days and pale, worm-like larvae emerge and feed on plants' roots for about two weeks. The nymphs molt several times, getting darker each time.
  • Adults: After the last molt, the nymphs pupate for about five days and finally emerge as adults ready to mate and lay eggs. A fungus gnat's life, from egg to adult, lasts about 17 days.
  • Controls:

Fungus Gnat Larva

A. Take care to minimize fungi in your grow room by cleaning up spilled water and nutrient solution, and use fans to circulate air, which helps prevent the growth of mold and mildew.

B. When those ugly fungi do show up, wipe them out with a treatment of sulfur-based fungicide, which will not harm your plants.

C. Set up sticky traps to monitor and capture fungus gnat adults.

D. Spray a combination of insecticidal soap and pyrethrins where the nymphs have clustered.


  • Mealybug Eggs: The cottony masses found mostly on the underside of leaves look like the fungal disease known as downy mildew, but they could contain 300 to 600 round, yellowish-orange mealybug eggs. They're laid over a 10- to 20-day period.
  • Nymphs: The eggs hatch in one to three weeks and the tiny, yellowish-orange nymphs begin roving around in search of feeding sites, typically clustered in protected areas such as in branch crotches or on stems near the soil line. As they feed, they secrete honeydew, which can result in patches of black sooty mold on leaves. The nymphs go through three instars, each lasting about a month.
  • Adults: Mealybug bodies are distinctly segmented and are covered with a waxy coating as they age, just like their close relatives, scale.Mealybug Larva
  • Controls:

A. Because adult female mealybugs don’t fly and the nymphs don't crawl very fast, the most likely way for them to get into your indoor garden is on plants you've brought in from the outside or from other growers. Thoroughly inspect every plant before they come into your grow room.

B. Spot-treat all of the egg masses with a neem oil formula.

C. Insecticidal soap kills mealybug nymphs and adults on contact.


  • Eggs: This pest can be hard to notice because the adult females never move, their green to brown bodies remaining attached to stems for up to three weeks after they lay their eggs beneath them. The eggs hatch while covered by the females' bodies.Scale
  • Nymphs: When the nymphs (known as "crawlers") emerge, they are yellow and have six legs around their oval bodies. The legs enable them to move away from the immobile adult and find spots to feed themselves, inserting their piercing mouthparts into plants and sucking out the sap.
  • Adults: After several molts, the nymphs' outer shells harden and turn brown or green, and their legs wither. They remain in place until they reproduce. In some species, the males develop wings as adults and appear as tiny gnat-like insects, but they are rarely seen and do not feed on plants. Females often reproduce without mating.
  • Controls:

A. Because adult scale are immobile, they are easy to remove with your fingers, but be sure to search thoroughly to find them all before they lay eggs.

B. The "crawler" stage is the best time to target scale with a spray that mixes pyrethrins, which shut down their nervous systems, and insecticidal soap, which strips away their waxy protective coating, causing them to dehydrate.


How is your grow room faring against the onslaught of thrips, aphids, and other bugs? Take pictures of your problem bugs and send them to the Safer® Brand team on Facebook, where you can get advice from our experts and the entire Safer® Brand community. Also be sure to subscribe to the Safer® Brand E-Newsletter for valuable coupon codes on our pest control products and links to more helpful articles.


Photos of Bugs on Plants

Cookies On This Site Ok This site uses cookies to improve your user experience. By using this site you agree to these cookies being set. To find out more see our cookies policy.