A Japanese beetle crawling on a leaf that has been chewed badly.
Shiny, copper and green Japanese beetles are a major summer pest. Adults eat plant leaves, and juveniles (grubs) eat turfgrass roots. The candy-striped leafhopper on the right feeds on plant leaves by sucking out sap, and it can infect plants with diseases. Photo by H. N. Kolich.

Japanese beetle – This shiny, metallic beetle was introduced to the U.S. through New Jersey in 1916 and has been spreading – and damaging crops, lawns, and ornamental plants – ever since. Japanese beetles are pests in both the juvenile and adult stages of life. As larvae, they live in the soil and eat the roots of lawn grasses. Following their spring feasting, the white grubs pupate for a couple of weeks, then emerge in June as adult beetles.

The adults are generalists; they’ll eat the leaves from a wide range of plants. In my yard, they prefer my thornless blackberry plants. I find that the beetles are more sluggish in the evening, no doubt full and tired from all that eating. They are easily hand-picked from the leaves, and dropping them into a bucket of soapy water is an effective, non-chemical control method.

If you notice a heavy infestation of Japanese beetles in your garden, you can treat lawn areas in August with milky spore bacteria (Bacillus papillae) to reduce the population of overwintering grubs. This natural bacteria is effective only against Japanese beetle grubs. A second application the following spring (late April to early May) will help knock back adult population even further. Chemical controls are also available.

Aphids – These small insects come in many forms and over 1,300 species. Many species are plant-specific, and their host preference is reflected in common names, such as green peach aphid, potato aphid, wooly apple aphid. They are often found on plant stems or the underside of leaves. They puncture the plant and suck out sap, causing plants to lose vigor. The sap passes quickly through their systems, and falls on to lower leaves of the plant. This sticky “honeydew” can cause further plant issues. It attracts ants, who appreciate honeydew so much, that they may tend or “farm” the aphids to keep them producing it. If ants don’t gather the honeydew, it turns into sooty mold, a black substance that coats leaf surfaces and prevents photosynthesis. Fortunately, several beneficial insects, such as lady beetles, readily eat aphids. Certain small wasps lay their eggs inside aphids, which provide food for the developing larvae. A strong blast of water from a garden hose will knock many aphids off plants. Spraying insecticidal soap on aphids is another low-impact control method.

An aphid crawling on a plant.
This wooly aphid is one of over 1,300 species of aphids in North America. Aphids cause primary plant damage by puncturing plant tissues and sucking out sap. Aphid droppings, called “honeydew,” may attract ants who use the sticky substance as a food source. Accumulations of honeydew on leaf surfaces turn into a black, sooty mold that interferes with photosynthesis. Photo by H. N. Kolich.
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