Beetles: here, there and everywhere

Just like the Beatles song said, "Nobody can deny that there's something there." Many of you probably noticed a lot of little shiny black beetles around your home and even out in the field. I've seen a few different beetles actively moving around. The sap beetle, or sometimes called the picnic beetle, can be found in high numbers in urban areas now. As the common name suggests, they are attracted to human food, like fruit and vegetables. But they are normally seen  feeding on overripe fruit and decaying organic matter. In a few weeks you may see them feeding on corn silks. They are also secondary invaders and will feed in corn husks infested by corn earworm. Most literature suggests they aren't an economic pest.

Sap beetles are black and shiny with four irregular spots on the forewings. Note the antennae are clubbed and the wings don't fully cover the abdomen. Photo by Joyce Gross, UC-Berkeley.

In addition, I've got reports of a few different flea beetles in corn. Corn flea beetles are common to see early in the season. Corn is the preferred host plant where the adults scrape along upper and lower corn leaves. They will also feed on grasses. The feeding itself isn't an economic problem, but they can vector a bacteria that causes Stewart's wilt. Foliar insecticides are not economically justified after V5.

Corn flea beetles are small, shiny and black. Note the enlarged hindleg femurs used for jumping. Photo by Mike Quinn, TexasEnto.net.

Another flea beetle out and about lately is the redheaded flea beetle. They are similar in size to the corn flea beetle, but more oval in shape and have a red head (funny how entomologists come up with common names!). They can feed a several weeds, corn and alfalfa.

 

The redheaded flea beetle also has enlarged hindleg femurs for jumping. Photo by Lewis Veith.

Getting creative to collect Japanese beetle

Many of you are talking about the high numbers of Japanese beetles in Iowa this year. They have increased exponentially in some of our small plot trials in central Iowa since last week. The dual-lure pheromone trap from Trece is one way to collect these adults. The lures are extremely attractive to Japanese beetle and can draw in adults from a mile away. So the traps are ideal for first detection in a new area, but not recommended as a management tool.

This Japanese beetle pheromone trap can fill up in about an hour right now in Story County, Iowa. Photo by Brent Pringnitz, Iowa State University.

In case some of you are wanted to see just HOW MANY Japanese beetles you can collect, a regular pheromone trap just won't cut it because it fills up too fast. Well, a few people have taken it to another level to see how many GALLONS they could trap in one day. Rex De Bruin and Chris Sparks at BASF Plant Science in Story County replaced the green collection container with a 13-gallon trash bag. They were able to fill it over night. We've done this in the past to use the beetles for lab assays and it is not a good smell.

This modified Japanese beetle pheromone trap (13-gallon trash bag) was filled overnight. The trap entrance was clogged with more beetles! Photos by Rex De Bruin, BASF.

Japanese beetles are hungry

Since I first mentioned seeing Japanese beetle about two weeks ago, I've had many reports of significant numbers around the state of Iowa. There have been a few look-alikes emerging, too, and a recent ICM News article can help with identification. Of course I have seen them on urban plants, but that is where I would expect to see them in June. I noticed adults feeding in corn, soybean and vineyards this week.

Normally, Japanese beetles feed on corn silks later in the season, but Mark Licht, ISU Field Agronomist, noticed them feeding on the corn leaves. I personally haven't seen this before, but I guess they have to feed on something until the silks come out. I did visit a few farms around Ames today and noticed adults in corn. I don't know if they were feeding or just trying to stay protected from the wind. I also noticed beetles defoliating young soybean. They often aggregate to feed and mate, so individual plants had skeletonized leaves.

Japanese beetles in V8 corn at the ISU Johnson Research Farm. Photos taken 14 June 2010 by Erin Hodgson.

 

Japanese beetle defoliation is often overestimated in soybean. Although some leaves were heavily skeletonized, the overall defoliation on these V2/V3 plants was <1%. Photos taken 13 June 2012 by Erin Hodgson. 

Japanese beetle feeding and mating on grape leaves at a winery in eastern Iowa. Photo taken 13 June 2012 by Erin Hodgson.

Ukrainian farmer visit

Today I gave a short presentation on corn and insect management to a group of Ukrainian farmers.

They are on a tour to learn more about agriculture in the midwest. Mark Licht, ISU Field Agronomist, organized a full day of talks and tours for the group. Roger Elmore, ISU Corn Agronomist, started the day with a review of corn production - a really interesting topic for them! I followed with a brief discussion on how we manage insects in Iowa. They don't have access to GMO's, and they asked lots of questions about our options in corn. European corn borer is the more important pest for them. I think they were surprised by how much a bag of corn could cost! Next Mark was going to review tillage, machinery and general production practices in Iowa and give them a tour of some ISU Research Farms.

It was my third time working with a Ukrainian farmer group. The translators are always great about getting my messages across. They thanked me with a hand-painted plant from the Ukraine!

Insects pick up activity in late May

The last week of May was a busy time for insects. Many people reported seeing insects in corn and soybean. Brian Lang wins the prize for finding the first soybean aphid of 2012. I think he usually finds the first ones, even though the prize is just a "woo hoo" from me. Finding winged aphids and first instars is difficult on VC-V1 soybean, so I always try to look for ants and lady beetles.

Lady beetles, pirate bugs and lacewing larvae find soybean aphid on young soybean and are easier to see than aphids. Photo by Marlin E. Rice.

I saw my first Japanese beetle today near the ISU Library. A few adults were destroying a rose garden as the blooms were trying to open up. I also got a few calls this week about white grubs feeding on corn and soybean roots. We have several white grubs as possible culprits, including annual, true and Japanese beetles. Unfortunately, there are no rescue treatments for actively-feeding grubs in field crops.

 White grubs have three pairs of true legs and are always in a c-shape.  Photo by David Cappaert, Michigan State University.

Many people are sending me great photos showing caterpillar damage in corn. Black cutworm is still actively damaging late-planted corn in some areas, but older corn (>V5) should be big enough avoid clipping. First generation European corn borer and corn earworm larvae can be seen in a few fields. For some reason ECB females are attracted to taller corn, so check those fields first (especially if they are non-Bt hybrids). Various armyworms, cutworms and thistle caterpillar have also been reported at low densities in corn.

Corn earworm caterpillars vary greatly in color, ranging from light green to pink to brown. They have light and dark stripes running length of the body. Photo by Clemson University. 

For more insect activity updates, read this ICM News article. You may be seeing more insects out there and I would appreciate any pictures or reports you may have.