They creep, crawl, fly and inch toward you. Insects, good and bad, are all around us. Have you recently gone beneath your trees and wondered what is all that sticky stuff falling down on you and coating your sideway, decks or even your vehicle? You probably didn’t know that sticky stuff may actually be excrement from insects. The cool spring temperatures have created a perfect environment for the insect world to explode in numbers.
This spring, our Master Gardeners have experienced a huge influx in the number of phone calls and office visits, not only on the sap-excreting aphid, but also other leaf-eating insects, such as leafrollers and plant bugs.
Of the top three questions handled by Master Gardener volunteers this spring, the overwhelming majority have been about aphids. Ash trees were attacked viciously by ash aphids. Homeowners often didn’t notice the damage until the leaves were tightly curled, protecting the aphids from control efforts.
In most cases, healthy, well-watered trees will recover from attack by aphids, as temperatures warm and beneficial insects like lady beetle larvae eat the aphids. A forceful steam of water before the leaves curl up works well to dislodge aphids from the tree. Aphids are soft-bodied insects that also can be easily managed with low toxicity products, such as horticultural oils and soaps.
Another common insect question is about the little caterpillars hanging on trees from silk strings and causing curled leaves. From apple and pear trees to hornbeam and maple, several different types of moths are laying their eggs, and tiny green caterpillars, called loopers or leafrollers, are chewing on the leaves. In most cases, the damage is minimal, and the trees can easily replace the damaged leaves. Similar to aphids, loopers are soft-bodied. When they are blown off the leaves by a strong water stream, they must crawl back to the host plant and often die before getting there. If numbers are out of control, you can also try a larvicide, which only effects caterpillars and does not harm other insects.
Our third most common insect problem this year is the honeylocust plant bug. These insects attack new growth on honeylocust trees, causing leaves to develop yellow to brown spots. The leaves then become twisted. Heavy infestations can sometimes cause twig dieback. In most cases, populations of the insect are reduced drastically with the onset of warm summer temperatures.
No matter what issue you may have in your landscape, proper identification of the pest is key. This will allow you to use the most effective control and minimize potential harm to pollinators and beneficial insects. Hosing plants down with water will not only take care of many pests, but will also rinse dust and insect residue off the plant leaves and provide needed water during the coming warm, dry summer months.
Wendy Hanson Mazet is the horticulture program coordinator for University of Nevada Cooperative Extension in Washoe County. Have questions about your plants? Contact a master gardener at 775-336-0265 or firstname.lastname@example.org, or visit www.growyourownnevada.com.