3 Invasive Insects to Look Out for this Summer

Invasive insects are a big problem. They not only wreak havoc on our lawns but are difficult and costly to control.

Here are three that will undoubtedly cause you a headache (if in your area) and how you can rid your landscape of these unwelcome guests.

Emerald Ash Borer
This beetle first appeared in Ontario approximately 20 years ago. Introduced from Asia, it is responsible for the destruction of millions of ash trees in North America. The bright, metallic green adults are hardly the problem, though; they feed on leaves but cause little or no damage to the tree itself. It’s their young that are responsible for the damage that leads to the tree’s demise. In late June, the beetle deposits eggs between bark crevices and cracks on ash trees. When the eggs hatch in mid-late July, the larvae bore down to the inner bark where they feed on the tree, creating long serpentine galleries. These ‘galleries’ disrupt the tree’s ability to transport water and nutrients from the soil to its leaves, resulting in its decline. Trees that are heavily infested will usually die within two to four years.

Signs of infestation: Yellowing or browning of leaves, typically in the upper canopy; S-shaped larval galleries in the wood under the bark that are packed with a mixture of sawdust and larvae excrement; and D-shaped exit holes in the tree bark. Increased woodpecker activity may also point to infestation as the bird likes to feed on beetle larvae and pupae.

Remedy: Insecticide use, which will typically remain effective for one to three years. However, it must be applied at the right time and in strict accordance with the product label to be successful.

Japanese Beetle
This beetle is easily identified by its colouring: metallic green thorax and head, and iridescent
copper-brown wing covers.

Japanese beetles are a serious pest for more than 300 types of plants, including vegetable crops, flowering plants and ornamental shrubs like rose bushes. They damage plants by eating the flowers and the leaf material between the veins. The larvae, called grubs, are also destructive, feasting on the roots of grass and plants from beneath the soil surface.

Japanese beetles can generally be seen from June through August or September. They are most active on warm, sunny days and prefer plants that are in direct sunlight.

Signs of infestation: Skeletonization of plants. Upon closer inspection of the plants, the beetles are easily seen feeding on the foliage.

Remedy: Shake the insects off into a bucket of soapy water early in the morning when they are sluggish. This will kill them.

European Earwig
Native to Europe, western Asia and North Africa, this earwig is now well-established here. It is more injurious to plants, particularly dahlias, zinnias, butterfly bush and hollyhocks, than native species.

These earwigs are reddish-brown in colour, with a slender, elongated body, set of short wings, which are rarely used to fly, and pair of pincers. They are primarily active at night. During the day they like to hide in dark, cool, moist places — in cracks and under rocks, logs, loose clods of soil and mulch in flowerbeds.

Signs of infestation: Dead plants and shrubs, activity near outdoor lights and a foul smell. Earwigs produce a pheromone, which can be strong when they cluster in larger numbers.

Remedy: Eliminate its hiding places followed by insecticide use. If the earwig’s place of shelter is not addressed, insecticide application will probably not control this pest very well.