The month of July is almost over but not our hot weather. Monsoon rains have helped with rain here and there and have kept the cap on temperatures with late afternoon clouds.
But that is not what I am going to talk about this week. The subject today is about entomology.
Entomology is the study of insects, and after all I am an entomologist. Did you know that all bugs are insects but not all insects are bugs? What about the butterflies, the dragonflies, the fleas, the beetles, the aphids? These are not bugs but are all in their own order just as bugs are in their order, hemiptera.
But enough about the science of entomology. Realizing that most insects are either good or neutral, we will now focus upon a few of the bad guys.
The first is the leafcurl ash aphid. It, of course, attacks green ash trees. Feeding by these aphids creates a tightly rolled up bunch of leaves, usually at the end of branches. Inside this ball are lots of aphids, their cast skins, and strands of wax coated with honeydew. Aphids colonize only young leaves that have not fully expanded.
Usually the damage is mostly cosmetic and populations of aphids crash by later summer when new leaves are no longer produced. Also, many natural enemies help bring this pest problem to an end. If you must control these insects, systemic insecticides such as Orthene or Merit work well as sprays.
Next on the list are the poplar twiggall flies. They produce a gall on new twigs of aspens starting in the spring. While these can be unsightly, rarely do they cause significant problems. It is possible that these galls could weaken these infested twigs and result in breakage of twigs or limbs later on in situations of heavy winds.
If you want to prevent this pest problem, I recommend using a systemic insecticide containing imidacloprid such as Merit, Malace, or Bayer tree and shrub insecticide. A soil drench in the fall, following label directions, will result in up to 12 months protection, certainly long enough to control the single generation in the spring.
The next two pests attack honeylocust trees. The first is the honeylocust spider mite. While mites are not really insects, entomologists generally are responsible for dealing with them. These mites feed on the undersides of the leaves leaving a multitude of small flecked wounds. Heavy infestations can cause leaves to turn yellow and eventually can cause premature leaf drop. Mite problems are most prevalent on trees planted along roads and in parking lots; typical hot, dry places.
There are several miticides that can control mites once they appear, but the best approach would be to apply horticultural oil when the tree is dormant and leafless. This will kill overwintering eggs and females. To avoid problem mites, plant honeylocust trees in irrigated areas where lower temperatures and higher humidity will discourage their development.
Last but not least is the honeylocust plant bug. This bug feeds on developing leaf buds and leaves, resulting in discoloration, deformation of developing leaves and even death of younger leaves. Twig dieback can occur under severe infestations. May and June are the months when infestations begin to be noticed.
This insect is easily controlled with most insecticides available to home-owners. I would look for this pest by mid May with plans to spray if detected. Damage found in July can- not be reversed through spraying.
Well, that is it for this week. Some of my future columns will address even more of these public enemy insects of landscape trees and woody perennials. Until then, keep cool, garden early in the day, keep pulling those weeds and keep the faith. Beautiful gardens can be had by all.
Jim Leser retired to Cedaredge after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a master gardener.blog comments powered by Disqus