Garden Views: Fun and not so fun insects


Fireflies also known as lightning bugs have appeared! These insects are in the beetle family Lampyridae and are considered a summertime favorite, though this year they are appearing in late spring. Even the most squeamish among us must admit awe and fascination over these beetles with glowing butts.

Fireflies’ lifecycle involves an egg, larva, pupa, and adult. Eggs are laid in moist humus, leaf litter or moist soil. Upon hatching, many Ohio species will spend two or more years as predatory larva in the soil eating snails, slugs, worms, and other smaller soil arthropods like springtails. They then pupate and appear as adults to feed, mate, and lay eggs.

To increase fireflies in your landscape for years to come use leaf mulch or wood mulch around plants to mimic the humus layer where eggs may be deposited, and to conserve moisture. Preserve waterways and aquatic habitats that lightning bugs will favor. Reducing outdoor lighting also helps them to show off their lights and find each other to mate and produce the next successful generation of our favorite summertime light show.

Another insect that has appeared is the Spongy Moth. The spongy moth, Lymantria dispar (formerly the European gypsy moth) is a non-native, invasive species that has moved west into Ohio from Pennsylvania and south from Michigan. This insect is not fun and can cause havoc to your landscape.

Each egg mass an adult female moth lays can contain between 500-1,000 individual eggs; once hatched the larvae or young caterpillars are able to feed on the leaves of over 300 different tree and shrub species. Egg hatch occurs about the same time as redbud trees are blooming.

As the caterpillar becomes larger, the more they can consume and are known as leaf feeding machines. Oaks trees tend to be their favorite however they seem to enjoy spruces as well. The feeding injury is especially hard on evergreens, and I have observed spruces dying in a single season where nearly all the needle foliage was consumed. Normally healthy deciduous trees can usually withstand two years of defoliation before they decline.

The worst part in my humble opinion is what goes into the caterpillar’s mouth comes out the other end as insect excrement or what Horticulturists call frass. Imagine thousands of caterpillars frassing at the same time, and you are outdoors under the canopy of the tree being fed upon.

After the caterpillars compete their feeding frenzy, they will pupate and emerge as an adult moth. Female moths are white and are not capable of flying. The males are brown and fly in a zig zag pattern. The adult moths do not feed, therefore causing no additional damage to the plants. They do however want to find a mate so the female can lay an egg mass that will overwinter and hatch the following spring – and so the cycle continues.

Control of the caterpillars is by applying insecticides labeled for spongy moth. Choose products with the active ingredients: bifenthrin, cyfluthrin, cypermethrin, deltamethrin, permethrin, and others. These ingredients typically protect treated foliage for a week or two and multiple applications may be needed to maximize protection against spongy moth caterpillars. Thorough spray coverage is also needed as untreated foliage will not be protected. While homeowners may be able to spray smaller trees, larger trees will generally need to be treated by an arborist or a tree care company to achieve good spray coverage.

It is important to note that healthy deciduous trees and shrubs leading up to a spongy moth outbreak can handle a defoliation as a result of the caterpillar feeding by sending out an additional set of leaves later in the season as the feeding subsides when the caterpillars pupate and ultimately become adult moths. It is only after repeat defoliation that these plants typically show signs of decline or even death in some situations.

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