Posts tagged entomologist

What do lightning bugs eat / An Evening with Fireflies

     An upcoming event at the Indian Creek Nature Center prompted me to call one of our awesome entomologists at Iowa State University. The Nature Center is having a walk at 8 p.m. Friday featuring one of my favorite insects –  the lightning bug!  

Lightning bug/ David Cappaert, Michigan State University, Bugwood.org

Lightning bug/ David Cappaert, Michigan State University, Bugwood.org

    What’s not to love about lightning bugs? They light up dark summer nights with their intermittent flashes and unlike other nighttime bugs, they don’t bite – in fact, they kind of tickle when you catch them. Best of all, in their younger stage, they eat slugs and other pests. 

Lightning bug larva/ Gerald J. Lenhard, Louisiana State Univ., Bugwood.org

Lightning bug larva/ Gerald J. Lenhard, Louisiana State Univ., Bugwood.org

   I wrote about lightning bugs last year after attending a workshop led by ISU entomologist Donald Lewis. Until then, I had no idea that  lightning bugs, as larvae, dined on not only slugs, but other insect larvae and snails – a real beneficial beetle! But I’ve had a nagging question since then: what do adult lightning bugs eat? After all, kids catch lightning bugs all the time, put them in a jar, punch holes in the lid and throw some grass inside. So do lightning bugs eat grass??

   Probably not, was the answer.  Donald Lewis said, if anything, they might occasionally feed on nectar. Some female species of lightning bugs use the signal of a different variety of lightning bug to attract males, and then, well, the male doesn’t become their mate, but their meal!  So, that’s what that species eats, but, he said, most adult lightning bugs appear to not eat much of anything.

   As an aside, he noted that punching holes in the lid of a jar might be more harmful to lightning bugs than leaving the lid intact and not-too-tight on the jar. Lightning bugs come out at night because they need a certain level of humidity and would basically dry up in the hot summer sun. Punching holes might allow too much air into the jar and also dry out the bugs. Safest bet might be a catch and release method. Get a good look, admire their flashing lights and let them fly free.

     Here’s some info about Friday’s (June 5, 2009) walk:   An Evening with Fireflies, Indian Creek Nature Center, 6665 Otis Rd. SE, Cedar Rapids. 1 ½ mile walk on grass-surfaced trails. Members, $3; non-members, $5. Children, $1. For more details, see: http://indiancreeknaturecenter.org or call (319) 362-0664.

    REMINDER: Remember to stop by the Gazette/KCRG tent between 9-10 a.m. Saturday (June 6, 2009) at the Downtown Farmers Market in Cedar Rapids. Sign up for the drawing (rattles, corn-made dishes and other baby items courtesy of Dandelion Earth Friendly Goods) and let me know what you’d like to see on the Homegrown blog and in The Gazette. The tent will be in Greene Square Park, along 4th Avenue, close to the corner along the railroad tracks. See you there!

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Ladybugs, Lady Beetles

   They are red, orange or shades in between and tend to invade homes in late fall.

   Ladybugs and lady beetles are different names for the same bug that some people see as a pest, but I see as a benefit. I don’t have the large-scale home invasion that some people do, so that could be why I see ladybugs through rose-colored glasses. When they do come indoors, I have a spot for them on my houseplants.

   My houseplants spend the summer outdoors and are given a good shower before I bring them inside in the fall. I don’t use any type of chemical insecticide, and that’s where the ladybugs come in: put them on the plants and they spend their days looking for tiny bugs to eat. They’re amazing to watch in action.

 I know my solution isn’t for everyone, so following are tips from Iowa State University about indoor control and other helpful information:

Ladybug in action

Ladybug in action

 

  The Asian lady beetle is present all summer but is most noticeable in the fall when second generation adults migrate from trees, gardens and fields to reflective, vertical surfaces (such as the south side of the house) in preparation for winter hibernation. 

 

   Asian lady beetles are a beneficial biological control in trees during the summer, and in fields and gardens during the fall, but can be a severe household nuisance during late fall and winter. Wooded residential and industrial areas are especially prone to problems.

   The origins of the Asian lady beetles are not clear, although it appears the current pest species was not purposefully released in the United States or in Iowa. Beetles that arrived by accident in ports such as New Orleans in the late 1980s have crawled and flown all by themselves to all corners of the country.

   The multicolored Asian lady beetle is 1/3 inch in length; dome-shaped; yellowish-orange to red with variable black spots on the back. Deep orange is the most common color. The 19 black spots may be faint or missing. There is a black “W” shaped mark on the thorax.

   Asian lady beetles, like other accidental invaders, are “outdoor” insects that create a nuisance by wandering indoors during a limited portion of their life cycle. They do not feed or reproduce indoors; they cannot attack the house structure, furniture, or fabrics. They cannot sting or carry diseases. Lady beetles do not feed on people though they infrequently pinch exposed skin. Lady beetles may leave a slimy smear and they have a distinct odor when squashed.

   Asian lady beetles follow their instinctive behavior and fly to sunny, exposed surfaces when preparing to hibernate through the winter. The time of beetle flight varies but is usually from mid-September through October (depending on weather.) Light colored buildings and walls in full sun appear to attract the most beetles.

   Sealing exterior gaps and cracks around windows, doors, eaves, roofs, siding and other points of access before the beetles appear can prevent unwanted entry. Experience suggests, however, that comprehensive pest proofing is time-consuming, often impractical and usually not 100% effective.  For large infestations with intolerable numbers of beetles, spraying pyrethroid insecticides such as permethrin or esfenvalerate to the outside of buildings when the beetles appear may help prevent pest entry. Homeowner insecticides other than pyrethroids usually do not provide satisfactory prevention.

   Long-term relief may come from planting trees that will grow up to shade the south and west sides of the house. The most practical control for beetles already inside is to vacuum or sweep them up and discard. Indoor sprays are of very limited benefit. Interior light traps are available.

Donald Lewis, of Iowa State University’s Department of Entomology, adds the following about ladybug myths and facts:   

Myth: Ladybugs are different from lady beetles

Fact: Ladybugs and lady beetles and ladybird beetles are all different names for the same thing.

Myth: Asian lady beetles come from soybean fields.

Fact: There are Asian lady beetles in soybean fields, but also many other places including trees and, gardens.

Myth: Soybean harvest causes multicolored Asian lady beetles to migrate to town and to houses.

Fact: Day length and temperatures trigger migration – expect swarms of beetles on first warm days after frost. Soybean plants lose their leaves, and therefore any aphids the lady beetles might be eating long before harvest. The beetles leave soybean fields as the plant leaves begin to turn yellow and not when the combines arrive.

Myth: Farmers released the lady beetles to eat the soybean aphid

Fact: No releases were ever made in Iowa. Multicolored Asian lady beetles arrived in Iowa by wandering from adjoining states several years before the soybean aphid appeared.

Myth: Lady beetles breed in the walls of the house during the winter.

Fact: They do not reproduce during the winter.

Myth: Finding a ladybug brings good luck.

Fact: This myth might not be all wrong. Since ladybugs eat aphids, other small insects, mites and the eggs of insects and mites, you could argue that ladybugs do bring good luck to farmers and gardeners. However, there is no evidence to prove that the good luck extends beyond the benefit of fewer aphids feeding on your plants.

Myth: You can tell the age of a ladybug by counting its spots.

Fact: There are over 5000 different species of lady beetles (ladybugs) in the world and approximately 475 species in North America. There may be as many as 100 different kinds in Iowa. The numbers and arrangements of spots on the backs of ladybugs are distinctive for the different species, and once a lady beetle emerges as an adult it never changes its spots.

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Attracting pollinators

Most people would rather keep bees at bay, but Steve Hanlin, entomologist with the US Department of Agriculture research station in Ames, Iowa, understands their value as pollinators. To Steve, bees and other pollinators have a multi-billion dollar impact on what we eat and wear.

Steve spoke at Sunday’s Honey Fest at the Indian Creek Nature Center. His mention of Osmia bees was met with a round of applause by some of the beekeepers in the audience. That type of bee, also known as the Mason bee,  does not sting.

  The USDA mostly uses honey bees for their pollination of heirloom crops, which are raised by staff in Ames, but Steve called the bumblebee the “best wild pollinator there is.” The cost of bumblebees is more prohibitive, so they’re not used as often by his group.

For people with apple orchards or other plants in need of pollination, Steve said it’s best to not spray weed beds and to not use a rototiller. Both destroy habitats where bees like to live.

Old mouse nests are an ideal spot for bumblebees, but encouraging mice to live nearby raises its own questions. Basically, bumblebees live in undisturbed sandy soil.

Steve said osmia bees can be attracted by placing cardboard straws in an empty Pringles can where the bees can live. Plastic straws don’t work, as the bees would suffocate. The cardboard straws are what mail-order bees are shipped in, he said. Another “bee house” can be seen in the photo above.

 As an aside, Steve said moths also pollinate, but only night-blooming plants.

Also, some types of cactus are endangered because their pollinators, bats, are declining in number.

Honeybees don’t pollinate trumpet-style flowers, he said, and while bumblebees make little “honey pots” Steve doubts that people who buy bumblebee honey are getting the real thing. The honey, produced in tiny quantities, would have to be extracted by micro-pipette, he said.

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What bugs you?

    Something under my back porch steps caught my eye. That one piece of plastic from a backyard toy led to the discovery of other “treasures” half-buried by grass: a golf ball, broken rain gauge, half of a plastic Easter egg and an empty plastic cup. Make that, partially empty cup. A tiny amount of rainwater had trickled inside, offering the perfect breeding spot for mosquitoes. In fact, any of those items, except the golf ball, could potentially provide what mosquitoes need to multiply. It doesn’t take much.

    Ken Holscher, associate professor and extension entomologist for Iowa State University, said he wasn’t precisely sure how much water is needed for a mosquito to complete its life cycle, but said if there is at least 1 inch of water present for 7-10 days, (or as long as it takes to complete their immature development) and sufficient organic material to serve as a larval food supply, that’s all that’s needed to produce a batch of mosquitoes.

   Holscher said mosquito larvae are considered to be “filter feeders” that use their mouthparts to filter and feed on bacteria and microscopic bits of algae, fungi, and other organic detritus in the water.  Cleaner water will typically produce fewer mosquito larvae.  However, the standing water that collects in outdoor areas during the summer will usually have enough organic material to produce at least some mosquitoes.

   The Culex species of mosquitoes that can carry West Nile virus, St. Louis encephalitis and other diseases that cause brain infection, like to breed in containers, such as mine, or old tires.

   It didn’t take long for me to pitch the half-buried treasures. I’ll keep a closer eye on my bird bath and fountain, as well, to make my yard less hospitable to these unwanted summer pests.

 

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White grub watch

The following information is from Donald Lewis, Iowa State University Extension entomologist. For more information from Lewis on grubs, as well as insects,  see the Feb 3 “Lightning bugs eat WHAT??” blog post.

 

Spring is here and the grass looks as good as it is going to look all summer. Since you want to keep it that way you have probably been considering treating for white grubs, either because you have experienced white grub damage in the past, or your friends and neighbors have complained about white grub damage, or a lawn care salesperson’s pitch got you a little excited if not a little scared. Put the insecticide down and step away from the sprayer. We need to talk.

 

Biology and Habits

The white grubs that routinely damage lawns in Iowa are called annual white grubs. These root-eating, underground June beetle larvae have one generation per year and take one year to complete their life cycle of egg, larva, pupa and adult. The adult beetles of our annual white grubs are specific kinds of June beetles called masked chafers. They are tan or straw brown in color and as the name implies, they have a black stripe across the eyes and face. The masked chafers begin flying in late June and lay eggs in the turf during July.

 

The eggs hatch in two to three weeks and tiny white grub larvae begin to eat the grass roots. The grubs grow rapidly and are fully grown at one inch in length by late August or September. White grubs are pudgy, off-white except for the brown head and typically bent in the shape of the letter “C.”  Feeding by the grubs prunes the roots from the plants and causes the grass to wilt and fade. 

 

Extreme feeding by populations of 10 or more annual white grubs per square foot will cause the grass to die. White grubs move several inches deep in the soil to spend the winter. They move back near the surface in the spring time but cause little additional damage as they wait to pupate in June, emerge as adults and start the cycle over.

 

Management Options 

White grub populations and damage to lawns vary greatly from year to year and place to place, even varying from spot to spot within the same lawn due to variations in beetle numbers, weather, turfgrass vigor, soil conditions and other factors. There is no method that predicts if and where grubs will occur or how severe the damage will be. What happens in your lawn this summer is a random event and not directly tied to previous experience. Therefore, decisions concerning white grub management are difficult; there is no one right answer for everyone.

 

There are three basic approaches to grub management in the home lawn, depending on your tolerance for damage, comfort with pesticides and willingness to spend the cash. White grub insecticide treatments are not only expensive but hard to justify from an environmental standpoint.

 

In places such as golf courses and some lawns, the risk of any white grub damage is so intolerable that preventive insecticides are applied to every part of the lawn, every year. When this approach is chosen, the proper time of application is between early June and Aug. 15. A compromise modification of the golf course approach is to treat only those areas that have been previously damaged. Beetles tend to return to the same areas in successive years, so it is logical to treat the areas where the grubs were last year or the year before.

 

The second approach is the wait-and-see approach. Watch the lawn carefully for early signs of damage (wilting, turning brown) during August to early September when grubs could be feeding. Apply a curative insecticide only where and when needed. The risk is that you might still lose some sod, especially if summer rainfall or irrigation keeps the grass growing and vigorous through July and August. Damage symptoms may not appear until after it is too late for effective treatment (late September through late October).

 

Unfortunately, raccoons and skunks are much better at locating grub populations than we are and the first symptom of a grub problem in your turf is likely to be that your lawn was “plowed” by varmints overnight.

 

The final alternative is to do nothing. This may be easier to do if you count up how many years you DID NOT have grub damage. Divide the cost of replaced sod by that number of years. If the yearly-averaged cost is less than the price of insecticide, do nothing and take your lumps in the occasional year when damage occurs. This approach is much easier to follow if you believe “it’s just grass, anyway.”

 

White grub management decisions are difficult and frustrating. Many homeowners are frightened into applying grub controls because of advertisements on TV, in plant centers or because of horror stories they have heard about grub damage. Studies at Cornell University have shown that more than 70 percent of all grub control treatments were applied needlessly because there were no grubs in the lawn.

 

If you do choose to apply insecticides, read the application directions carefully before buying. Some grub treatments are preventive and must be applied before mid-August. Others are curative and work only if the grubs are present. Know which you are getting before you buy. Apply carefully according to label directions and thoroughly water in the insecticide. Watering accomplishes two things: it moves the insecticide into the soil where the grubs reside, and it removes the active ingredient from the surface and greatly reduces the hazard of insecticide exposure to people, pets and wildlife walking on treated turf.  Irrigate the treated area with at least one-half inch of water.

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