Aphids are small sap sucking insects and members of the superfamily Aphidoidea and the family Aphididae. There are many different species (more than 5,000) in the aphid family.
Aphids come in a variety of colours like green, yellow, black, red or brown. Their bodies are oval shaped and if you look very closely you will notice that they have long whip like antennae.
An aphid infestation normally starts with a few adults feeding on a plant. If the plant is a suitable host, these scouts deposit approximately a dozen wingless nymphs, through an asexual form of reproduction called parthenogenesis.
These female nymphs feed on the sap of the host plant and can produce numerous offspring per cycle. As the cycle is repeated throughout the spring and summer season the aphid colony grows exponentially. The host plant will soon covered in aphids. The aphids eat large amounts of sap from the host plant in order to get adequate nutrition. The aphids also excrete a substance called honey dew, which contains a high percentage of sugars.
SIGNS OF INFESTATION
Ants on your cannabis plants are often a sign of aphids. This is because the honeydew excreted by aphids attracts ants, who feed on the honeydew. The ants have a symbiotic relationship with the aphids and in return for honeydew the ants fiercely defend the aphids from insect predators. This might sound very farfetched, but it is scientifically proven ant behaviour.
The honeydew excreted by the aphids can also attract a type of fungus commonly referred to as “black sooty mould”. The black sooty mould grows on the honeydew deposits and colours the host plant’s leaves and stems black. Black sooty mould is usually a sign of an advanced aphid infestation.
Initially aphids tend to hide under the leaves of the host cannabis plant until such time as the infestation reaches larger numbers and then the aphids should be visible on the leaves and stems. The green variety of aphid may be more difficult to spot at first due to the colour blending in with the leaves.
Due to the high amounts of plant sap that the aphids suck from the host plant you should see signs that your infested cannabis plants are struggling. These signs may include wilting leaves, curling leaves, yellowing leaves and general stunted growth of your cannabis plant.
A great environmentally friendly way of helping prevent an aphid outbreak is by making use of companion plants.
Companion planting is a process whereby the growing environment are improved by planting beneficial plants close to one another. Individual plants protect others against pests by emitting a strong odor that should help deter aphids from reaching your cannabis plants.
Some of the best companion plants for keeping aphids away from your cannabis plants are coriander, basil, dill, garlic and chives. For more information on companion plants please see the section on companion plants.
Aphids spread by winged colonizer females, who lay eggs on the new plants they wish to colonize. This means that outdoor growing areas are most at risk of an aphid infestation and that it is very difficult to prevent these winged colonizer female aphids form reaching your outdoor growing area. One way of keeping the aphids away from your outdoor cannabis plants would be to make use of companion plants as discussed above.
The best strategy with outdoor aphid control is to regularly check your plants (at least once a week), this will hopefully enable you to catch and control the aphids early on when the colony is small and manageable.
Indoor growing areas are less likely to be reached by winged colonizer females than outside growing areas, but aphids can still reach your indoor grown cannabis plants by other means – like bringing cannabis plants or clones into your indoor growing area from elsewhere/ outside. The answer to this problem is to only grow from seed in your indoor growing area or if you still decide to bring clones or other cannabis plants into your growing area from outside or elsewhere, you should quarantine these plants separately from your growing area for at least a week. Checking them regularly for aphids and other pests.
Even if you do not see any aphids or other pests (like red spider mites) during quarantine it is still advisable to dip the clone or small plants in a insecticidal soap solution before bringing them into your grow area. If you cannot dip the plants thoroughly spray them with an insecticidal soap solution.
If you find aphids on your cannabis plants a good first step is to prune off infected areas and dispose of it by putting it in the trash. After you have pruned off the infected areas you can try spraying off any remaining aphids with a garden hose (if possible).
If you are struggling with a heavy infestation of aphids, you can also spray your plants with an environmentally friendly insecticidal soap solution like Biogrow’s Neudosan. Please note that normal dishwashing soap is not insecticidal soap and using it could end up burning your plant leaves and not killing any aphids. It is very important to properly follow the instructions of the insecticidal soap you are using because if you do not accurately dilute the insecticidal soap you might end up burning you plants. One of the benefits of using insecticidal soap is that larger predatory insects like lady birds (lady bugs) won’t be affected if they come into contact with it in their adult form.
If the infestation still persists after trying insecticidal soap you can try spraying with neem oil. However be aware that the neem oil may also kill any other beneficial insects it comes into contact with. When using neem oil you should take care not to get it on your buds as it will leave a bitter taste and the effects of smoking neem oil coated buds on human health have not been properly studied (it could be harmful to your health).
If you see any ants on your cannabis plants you should eliminate them, because the ants will defend the aphids against natural predator insects such as ladybirds (ladybugs) and their larvae, tachina flies, parasitic wasps, praying mantises, lacewing larvae, hover fly larvae, tree crickets, small spiders and young assassin bugs.