Posts tagged monarch

Japanese beetles are back

They’re back.

Japanese beetles

Japanese beetles

I spotted the first Japanese beetle of the season yesterday on my raspberry bushes. I went to check one of my rose bushes and sure enough, there was another one, sucking the life out of a beautiful pink bud. Unfortunately, both got away.

The beauty of these copper-colored beetles belies the devastation they wreak. Adult Japanese beetles feed on more than 300 types of plants – turning leaves into lacy skeletons. As larva, the white c-shaped grubs feed on turf grass roots.

I’ve heard some people have luck with the Japanese beetle traps that can be found at garden centers. Others say the traps just lure more beetles into your yard. When I see just a couple of the bugs, I use the squish method, but as they become more numerous, I’ll try to control their numbers with soapy water.

Take a small bucket with water and dish detergent – any kind will probably work – and knock the beetles off the plants into the bucket. The beetles are more active at certain times of day and will fly off. Othertimes, they do a drop and roll, which is the best way to get them to fall into the bucket. Early evening seems to be the time when they are more sluggish and easier to catch that way. Obviously, if you are growing crops that the beetles are attacking, such as grapes (another favorite,) you’re going to need a different method of control. They also favor certain trees, but supposedly they don’t kill the trees as do pests like the emerald ash borer. I also wonder what they will ultimately do to the monarch butterfly population, as Japanese beetles devastate the monarch’s food source, milkweed.

Since they make my top 10 bad bugs list, the Japanese beetle and different control methods can be found in several posts on this blog. Just use the search box at the right to find more from city arborist Daniel Gibbons, master gardeners and others on this foreign invader.

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Letting milkweed grow

A monarch caterpillar makes its way along a milkweed plant in late July in Cedar Rapids, Iowa.

A monarch caterpillar makes its way along a milkweed plant in late July in Cedar Rapids, Iowa.

  

 

This monarch caterpillar was munching on common milkweed at my garden this weekend. As noted below, habitat destruction has reduced the amount of milkweed growing in the Midwest, which is the only food source for the graceful Monarch butterfly. That’s one of the reasons I don’t kill off all the milkweed in my gardens. Another reason: the scent of milkweed flowers, as another gardener once described it to me, is intoxicating. Unfortunately, my nemesis, the Japanese beetle, has managed to suck all the milkweed flowers to brown this year. More plants are springing up, and hopefully will bloom after the destructive beetle has gone underground. Though the caterpillars look a bit ominous, they won’t bother your tomatoes or other plants, so don’t poison or otherwise kill them off, as Monarchs already face a number of obstacles to survival.

 

 

 

 

 

 

   For more information on milkweed, the following came from the Monarch Watch Web site at www.monarchwatch.org

    Monarch larvae appear to feed exclusively on milkweeds in the genus Asclepias and several other genera of viny milkweeds in North America. Milkweeds are perennial plants, which means an individual plant lives for more than one year, growing each spring from rootstock and seeds rather than seeds alone. In the Midwest, milkweeds were historically common and widespread on prairies, but habitat destruction has reduced their range and numbers.

    Milkweeds belong to the family Asclepiadaceae, derived from Asklepios, the Greek god of medicine and healing. Though most members of the genus Asclepias are tropical, there are approximately 110 species in North America known for their milky sap or latex contained in the leaves. Most species are toxic to vertebrate herbivores if ingested due to the cardenolide alkaloids contained in the leaves and stems.

    When Monarch larvae ingest milkweed, they also ingest the plants’ toxins, called cardiac glycosides. They sequester these compounds in their wings and exoskeletons, making the larvae and adults toxic to many potential predators. Vertebrate predators may avoid Monarchs because they learn that the larvae and adults taste bad and/or make them vomit. There is considerable variation in the amount of toxins in different species of plants. Some northern species of milkweed contain almost no toxins while others seem to contain so much of the toxins that they are lethal even to monarch caterpillars.

 

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