Lace bugs

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Underside affected by lace bugs. August, 29, 2015

Lace bugs are tiny sucker insects difficult to see. Nonetheless, their effects are quite visible in late summer. It is the main pest I have experienced in my young orchard so far, and it is commonplace in mature trees. I discuss here if intervention is worthy or not.

Monosteira unicostata is the lace bug that affects almond trees in the Mediterranean region. There is no much literature about it, but I have learned that it has several generations during spring and summer. It loves high temperatures. It feeds in the underside of leaves, tiny black spots appear on it. The pest makes the tree look silverly or pale. It is considered to weaken the tree and reduce production.

I planted my orchard in 2013. I observed this pest in some trees, mainly affecting the weakest ones in the sunniest side of the orchard. The effects of the lace bugs appeared in late August. I did not appreciate them in the spring. In August, 29, 2015 they were present in most trees. Many have very visible symptoms, again in the sunniest and driest location of the field. In a mature orchard they affect virtually every tree, but almonds had grown with no problem.

I noticed that some young trees were completly free from lace bugs. They were those which were treated with thiametoxam in May because they were affected by aphids. This systhemic insecticide killed aphids and also seem to have killed lace bugs at their first stages, which explain that they were so healthy in late summer.

Lace bugs activity fades away in September, so delaying harvest is a good strategy to avoid itch.

Very affected tree. Silverly pale look. August, 29, 2015.
Very affected tree. Silverly pale look. August, 29, 2015.

All in all, I consider that the visual symptoms and the occasional itch that lace bugs cause when they bite do not pose any serious threat to plants or humans. I follow the no treatment option.

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