Aphids- Small, green bugs
Aphids- Leaves sticky from small green bugs
Aphids are very small, soft-bodied insects with long mouth parts that they use to pierce stems, leaves, and other tender plant parts in order to suck out plant fluids. Most plants have at least one type of aphid that feeds on it during the growing season or an off season warm spell.
Aphids are small, soft insects that are typically wingless. They are almost always found in groups or clusters of overlapping generations. They can be seen without visual aid and are easily smeared or squished when touched or if a finger is wiped across them.
Other signs include the presence of honeydew. This shiny film coats leaves and the understory of trees as aphids excrete the excess sugar they consume. Wasps, bees, and ants can often be found feeding on this sugar source. Often times, leaves turn black when the honeydew is colonized by a fungus called sooty mold.
Curled leaves can indicate leaf curling aphids which feed on leaves causing them to curl up and create a protective envelope where they are well protected from predators and foliar treatment attempts.
There are many different species of aphids, some of which are host specific and others that feed on a wide host range. They produce multiple generations per year and are capable of growing their populations at rapid speed by reproducing asexually. Some females will birth upwards of 12 individuals in one day! Because of this amazing reproductive ability aphid populations can jump from insignificant to harmful levels in just a matter of a few warm days.
Once populations become too high, winged forms are produced and fly to colonize new locations. Some mate and lay eggs, which is a reliable way to survive the winter in harsher climates.
Typically, damage is minimal from leaf feeding aphids. Damage can become significant if populations spike causing leaf deformation and massive honeydew problems. This causes plants to stick to each other and promotes the growth of black sooty mold which decreases the capacity of trees to photosynthesize.
Some aphids, like the Bow Legged Fir Aphid, feed on the soft tissue of branch bark causing damage to limbs on Concolor Firs that can lead to weakened wood and possible dieback if left untreated for long periods.
The best management is to help trees stay healthy and strong so they are able to defend themselves from aphids without human intervention. Proper watering and regular soil treatments help to ensure this ability.
If populations spike, a dormant oil treatment can be made before bud break in late winter or insecticidal soaps can be applied during the growing season.
There are also a number of insecticides that can be sprayed on foliage or applied systemically through the roots or trunk. The systemic applications can be applied in the dormant season and control population outbreaks for the entire growing season. It’s important to rotate pesticides if aphid problems continue to arise on the same tree. This will reduce the chance of aphid populations developing resistance to insecticides.