Woolly aphids - how do you treat them?

[Leo in N E Illinois]

Mealy bugs - wooly aphids - and other adelgids, are more common in the root zone when one uses an open, larger particle mix. For bonsai, we often use what to the mealy bug would be an open mix with good air penetration. The good air to the roots is essential for a good compact root system. Unfortunately, it means mealy bugs can still breathe "underground", if we used a heavy fine clay mix, we would have bad roots, but no problems with mealy bugs in our roots. The only solution, is to use your pesticide as a soil drench. Drench not just the foliage, but also submerge your pot in the mix, or thoroughly saturate the soil with the pesticide. This is for contact pesticides. For systemic pesticides the drench of the soil is not necessary.

As always, read the label of the pesticide you are using before you use it. Look to see if there are special instructions for use as a drench. Read to determine whether it is a systemic or only a contact pesticide. Read to know what the mode of action for your pesticide is. And as always, follow safety precautions.