Insects of Early Summer
My last insect blog dealt with three pests that emerge in early spring – aphids, tent caterpillars and Eriophyid mites (okay, technically not an insect). This time I’d like to discuss three insects that emerge in late spring to become a problem during the summer.
Flea beatles are so named for their incredible jumping ability. You see one, reach for it, and sproing… it’s gone. There is an amazing number of species throughout the world and they feed on everything from cole crops to corn, from shade trees to ornamental shrubs to perennials to weeds. That doesn’t mean that one species eats all these different plants, oh no. Most flea beetles prefer an exclusive diet, perhaps dining only on willows or potatoes. Unfortunately, the red headed flea beetle (Systena frontalis) is not among the picky eaters.
The shiny black body of this small beetle is topped with a dark red head that cannot always be distinguished as red. Eggs hatch in May and the larvae eat roots until they pupate and emerge as adults in June about the same time the Sweetspire (Itea) begin blooming. The larvae cause no appreciable damage, but adult feeding produces “shot hole” damage on thin leaves and scratching on thicker leaves.
Flea Beetle Control
Control can be tricky since they can easily move from plant to plant. A systemic insecticide applied to the soil just before hatching does wonders at reducing the population. Survivors can be treated with broad-spectrum insecticides as adults. Keep alert though, evidence shows that there are as many as three generations per year.
Michigan State’s website has additional information on identification and scouting:
Bagworms are curious beasties. Eggs hatch within the remains of their dead mother, inside the bag she began constructing as a larva. Hatchlings emerge in June when the Catalpa trees are blooming. They immediately begin spinning silken thread, which they fashion into conical “hats” that will become their life-long abode. As they grow, the caterpillars attach bits of plant to their baggy home. After about four molts, the caterpillars pupate and become adults in late summer. The male develops into a clear-winged moth. After he emerges from the pupal case inside his own bag, he flies to the bag of the female. The female develops into a distinctly unlovely creature that resembles a large maggot. She remains inside her bag, exuding pheromones to attract the male. After mating, the female produces roughly 500 to 1000 eggs inside her body before she dies. Both the bag and the female’s body protect the eggs until late spring, when the eggs hatch and the cycle begins again.
Bagworms can be found on a wide range of plants. They can defoliate whatever plant they happen to be on, so control is essential. That control is achieved through a relatively narrow window of opportunity. When the bagworms are small, they are vulnerable to a variety of insecticides. As they grow and add material to their bags, improving their “armor” as it were, that window of control begins to close. The importance of scouting to catch them at their most vulnerable cannot be overstated. If you miss that window, handpicking bags is an option. Make sure to crush them or otherwise dispose of them because the caterpillars are strong crawlers and will return to their plant if possible.
For additional information, Penn State has an excellent fact sheet:
Japanese Beetles were unknown to me before I moved to Illinois. All of my co-workers warned me of the coming invasion. But having no frame of reference, I had no clue, really. The beautiful little beetles showed up in early summer. Just a few at first, smashing into windshields on the highway or checking out what plants were on the menu. Then the main body of the invasion rose from the ground like a plague of old Egypt. Okay, yeah, that’s overstating it some, but that was what it felt like, the first season I saw them. They just kept coming.
Japanese beetle adults emerge about the same time that Queen Anne’s Lace and Chicory are blooming. Linden trees, roses, willow and smartweed are a few of their favorite things. When one beetle begins feeding, it releases a pheromone that attracts others to the same plant. That is why you often see masses feeding together, someone rang the dinner bell. And when they are finished, only the skeletons of the leaves remain.
Identifying Japanese Beetles
How can you tell if it’s a Japanese beetle? There are several metallic green insects, so some people get confused. Japanese beetles are about 3/8 inch long and ¼ inch wide with metallic copper wing covers over a metallic green body. They have five tufts of white hair on each side of their abdomen, which is a distinctive identifier.
Japanese Beetle Life Cycle
The adults mate after emerging in June and the female burrows into the soil to lay her eggs. She will lay 40-60 eggs over her lifetime. After the grubs hatch, they eat plant roots until fall. As the soil cools, they burrow deeper to hibernate for the winter. When soil warms up in spring, the grubs move closer to the surface and feed until they pupate in late May or early June. When the adults emerge in June, the cycle begins anew.
Controlling Japanese Beetles
Japanese beetle control has many facets. Quarantines operated by the USDA-APHIS are used to help prevent the spread of the beetles from infested to non-infested areas. Since eggs and grubs require moist soil, irrigation modification can be used to help regulate the pest. Several bio-control options are available; including parasitic wasps, nematodes and Milky Spore disease. Japanese beetle traps can be used, but the lure is so successful that it draws beetles in from a mile away. Place the trap far from any desirable plants. Most nurseries spray insecticides to kill the adults that invade. Since Japanese beetles keep coming from other areas, spraying must continue until they are gone for the year. Drenching insecticides to kill the larvae is also an option.
The Japanese Beetle Harmonization Plan contains additional information on control:
Japanese Beetle life cycle chart