Aphids are among the most common of garden pests. They’re relatively soft, squishy and destructive. There are thousands of species, and their reproductive strategies are 
What’s that in the shadows?
Aphids!
I’ve seen them approach 1cm, but most in my garden are several millimeters long. 
Ahpid close-up
Depending on the severity of the infestation, control practices can range from blasting the insects with a hose to insecticidal soaps, topical oils and pesticides to systemics. More environmentally friendly approaches include the release of aphid predators like the ladybug. As aphids grow, 
Aphid exoskeletons
Ants commonly “farm” aphids for their 
Uh-oh
Aphids on pine
Aphids often focus on weak foliage, and they further weaken any foliage upon which the feed. 
Aphid damage on last year’s needles
Given enough time to feed on pine foliage, they can cause needles to yellow and die. Unchecked infestation can do the same to entire trees. And because aphids can be vectors for harmful viruses, they can pose a significant threat to bonsai. 
The branch on the left lost its needles due to aphid damage
Treating aphids on pine is the same as treating them on broadleaf trees. Avoid aphids as much as possible by providing enough light and fresh air in the tree’s interior. Keeping plants overly full and crowded next to each other on the bench creates ideal conditions for aphids. Just say no – give your trees the space and sunlight they deserve!
Occasionally aphids provide disguises for themselves. Fortunately, in the case of wooly apple aphid, the disguise is the giveaway.
Wooly apple aphids on apple
The small, brown aphids create fluffy, white secretions in which they hide. The cotton-like structures are often found close to buds. Treat them like you would other aphids.
Close-up
Wooly apple aphids
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Ray says
Hi Jonas, what deterrent are you using?
Scott says
Love the pests posts. Thanks for all the good info!
I hope I’m not jinxing myself when I say I have few problems with scales and aphids. I’ve mostly been battling spider mites but most of my attention is given to mealybugs on my indoor crassula’s and other succulents. Is there anything in the works for a mealybug pest post of the week :)?
-Scott (Washington DC)
Jonas Dupuich says
Hi Ray – I’m thinking of applying neem oil and a systemic with imidacloprid. I think of treating bonsai this time of year as a first line of defense against the more virulent infestations that often strike in early spring.
I may also use lime sulfur on the black pines if it gets cold enough. Lime sulfuring trees that are actively growing can burn the foliage.
Jonas Dupuich says
Hi Scott – spider mite can be a difficult pest to manage and mealybugs are among the more annoying. I’ll see about a post if I can come up with photos. In the meantime, mealybug control is similar to scale control. As I don’t have experience with jade indoors, it might be worth posing the question at http://ask.bonsaitonight.com to see if other readers have suggestions.
Francesca says
Thank you for the useful info! I have problems with aphids so it is incredibly helpful for me. Thanks for sharing!