Insect Updates - Page 13 of 32 - Insects in the City

Bug with a punch

Posted on May 13, 2015 by p-porter

As pretty as they are, fourlined plant bugs like to stay out of sight. Look for damage first, then the bugs.

I ran a story about this insect 5 years ago, and thought it might be time for a refresher course. The fourlined plant bug, Poecilocapsus lineatus, is a small, attractively colored insect that is active right now. Don’t be fooled by its pretty face. This insect has been recorded as a pest from about 250 different plant species, both herbaceous and woody plants. Herbs, mints, and composite flowers seem to be especially favored.

What makes the fourlined plant bug unique is the rather severe damage (see image) that can be caused by relatively few individuals. Its damage is one of the most severe for a leaf-feeding bug of this size, according to USDA scientists who recently reported on the feeding behavior of these insects. They found that the four-lined plant bug’s saliva, produced by unusually large salivary glands, making up 15-20% of the insect’s body weight. In addition the saliva itself packs a special punch. Special enzymes attack the glue that holds plant cells together, causing pits in the leaves where the cells literally collapse after feeding.

The damage on some plants look like round pits or craters. On other plants feeding spots are delineated by leaf veins. The pitted areas eventually turn black or translucent, and may eventually drop out of the leaf, leaving holes that sometimes looks more like a caterpillar than a sap-feeding insect.

Fourlined plant bug damage on Shasta daisy appears like round pits.

Most of the damage seems to be caused by the nymph stage. By the time adults appear much of the damage has been done.

Treatments for fourlined plant bugs include insecticidal soaps, oils or other insecticides labeled for the plant attacked. Soaps and oils will be most effective on the wingless nymphs, and may not harm the adults. Sevin, malathion, and some of the newer pyrethroids, such as cyfluthrin and permethrin, should work well against both nymphs and adults.

If a close inspection of the plant reveals no insects, don’t treat. Also restrict your treatments to just those plants in the garden that show damage. There is little need to treat other plants and you’ll minimize your impact on beneficial insects. And don’t treat plants in bloom that are attracting bees. If you need to treat flowering plants, do it late in the day, just after sunset when bees are no longer foraging.

Kern’s flower scarab

Posted on May 6, 2015 by p-porter

Color variation in Kern’s flower scarab.

I’ve received several reports this week from worried gardeners concerning an attractive (yes, bugs can be pretty!) beetle feeding in flowers. The Kern’s flower scarab, Euphoria kernii, is a medium-sized (8-11 mm-long) beetle reported to feed on pollen of a number of different species of flowers ranging from roses to irises to certain grasses. Coloration and markings of this beetle is also variable, ranging from all black to nearly all yellow with black markings.

There are several species of Euphoria found in Texas, but the one that seems to be common now in the Dallas area is E. kernii. All Euphoria are found in fields, meadows and thickets and are abundant in early spring (April-May). An interesting thing about these beetles is that after feeding on flowers their larval habitat is reported to be in the nests of pack rats or mounds of soil associated with other ground dwelling rodents like pocket gophers.

A decision about whether to treat these interesting beetles is up to the individual gardener. Sevin (carbaryl) and any of the common garden pyrethroid insecticides are effective against a wide range of chewing insects, and should work well against these beetles. But for my part I’m hoping you’ll put up with a little damage and simply admire the beetles for their colors and their interesting place in nature.

Flag waving for Americans

Posted on May 5, 2015 by p-porter

Ensign wasp, Evania appendigaster. The dark, flag-like abdomen, here just visible behind the wings, gives the insect its name.

The ensign wasp is one of the odder insects found occasionally in homes. A small insect, only 5-7 mm long, it does not sting or bite. In fact, it does no harm; but it is a beneficial parasite of at least three household cockroaches, the American cockroach being the most common.

Ensign wasps are experts at locating not the cockroaches themselves, but the egg cases (oothecae) that cockroaches deposit. According to one account, when the female ensign wasp encounters a cockroach egg case, she first taps it with her antennae, presumably to confirm that it is an acceptable host for her egg. Then she lies down beside it (I have never heard of an insect voluntarily lying on its side before!) and braces her legs against the ootheca. After much labor she inserts her slender ovipositor into the tough ootheca and lays a single egg. After hatching, the wasp larva matures while feeding on the dozen or more cockroach eggs inside each ootheca. No cockroaches will hatch from an egg case that has been parasitized by an ensign wasp.

The name ensign wasp comes from the unique, stalked abdomen. Shaped like a sailor’s signal flag, she frequently waves her abdomen up and down while stalking her prey as if to say, “Here I am! Look out cockroaches!”

Egg cases produced of the American cockroach (shown here) make up food for the ensign wasp.

If you find an ensign wasp in your home, there’s no need to panic. It likely means that one of the larger species of cockroaches (American, Smoky brown, or Oriental cockroaches) is present somewhere inside the structure. I see one or two of these wasps in my office building every year. I know they come from the rarely seen population of American cockroaches lurking in the walls and ceilings of our office building–something found in nearly every commercial building. I like to think that we don’t see a lot of cockroaches because we have these little wasps keeping watch.

If you see these wasps AND see cockroaches on a regular basis, you may want to consider some control action. Against the cockroaches, not the wasps! One home owner recently swore that the ensign wasps were coming at her, and were tough to kill. Not true, though they do look impressive when they wave their little flags. The only ones who should get nervous about ensign wasps are the cockroaches.

For more information about cockroaches around the home, see the fact sheet Cockroaches and Their Control.

Tent caterpillars without the tent

Posted on April 10, 2015 by p-porter

Forest tent caterpillars rest between feedings on a silken mat where they may be easily seen and treated. Photo via NBCDFW Channel 5 TV.

Forest tent caterpillars are one of the most widespread and abundant of the tent-making caterpillars. Like their close cousins the eastern tent caterpillars, forest tent caterpillars feed primarily on trees; but unlike their cousins, and the common fall webworm, the forest tent caterpillar doesn’t make an actual tent. Instead the caterpillars aggregate between feedings on a silken mat which they spin on some area of the trunk or on large branches of the host tree.

Forest tent caterpillars are relatively easy to recognize. Besides their distinctive aggregation behavior, caterpillars can be recognized by their dark-gray to brownish body color, with pale-blue and yellow lines extending along each side, and a chain of distinct whitish shoeprint-shaped spots running down the middle of their back. After completing their immature development in two or three weeks, they pupate and eventually turn into a handsome but mostly obscure brown moth.

Forest tent caterpillars appear once a year, usually in April, sometimes in very large numbers. Then they “disappear” for a whole year until the cycle begins again. Some years caterpillar numbers are very high, but most years they may be noticed only by the sharpest-eyed observers. The cycles of up and down appear to be driven by a combination of environmental and natural control factors, like birds and parasitic insects. This may be one of those abundant years, at least for some areas. Sam Houston Electrical Cooperative reported dozens of power outages this month from masses of tent caterpillars covering electrical transformers, causing fuse overloads. I have received several emails over the past few days from residential areas with pictures of caterpillars massed on their silken mats.

Heavy caterpillar infestations on neighboring trees overflow onto an electrical transformer. According to Sam Houston Electric Cooperative there have been dozens of power outages caused in this way in the past week. Photo by Sam Houston Electric Coop.

If your favorite tree has a case of these leaf feeding caterpillars, there is probably little reason for concern. Most trees can easily withstand 20% loss of foliage with no harm, and in most residential locations most infestations will likely not have a major impact on tree foliage. In the event of heavier infestations, even when trees are completely defoliated, deciduous trees usually re-leaf and recover quickly. However when other stressors are present (e.g., drought, disease, physical damage to the tree from construction, etc.) and there is heavy defoliation, trees may experience slowed growth or dieback of parts of the tree.

If you notice trees with lots of caterpillars you may be able to protect at least some of the foliage by treating with insecticide applied through a hose-end sprayer. Spinosad and Bacillus thuringiensis are two low-impact insecticide ingredients that are effective against caterpillars. Even better, if you can see and have access to the large resting mats of caterpillars on the trunk, simply spot treat the caterpillar aggregation with a spray bottle using insecticidal soap, horticultural oil, or any pyrethroid insecticide. Such applications, being very targeted, will control the caterpillars with little impact on other beneficial insects.

For lighter infestations, I recommend letting the caterpillars be, and let the birds have their way with them. For more information on tent caterpillars, see https://insects.tamu.edu/extension/publications/epubs/e-218.cfm

Cankerworm caterpillars hit Texas trees

Posted on April 6, 2015 by p-porter

Dark form of the spring cankerworm. Note the three pairs of true (jointed) legs on the front of the body, and the two false (un-jointed) legs on the abdomen. The lack of legs in the middle of the body causes a cankerworm to walk in the typical “inchworm” fashion.

This week I’m receiving reports about spring cankerworm infestations in counties west of the Fort Worth, Texas area. Spring cankerworms (actually caterpillars, not worms) feed on a wide range of trees, and can defoliate trees in early spring. Although cankerworms are present in low numbers every year, periodically conditions are right for widespread outbreaks. The last time I remember this happening in the Dallas area was about 11 years ago.

If the reports are correct, this might be another “year of the cankerworm”–at least in some Texas counties. And as if to confirm this prediction, a few minutes ago a spring cankerworm dropped on my shirt from the oak tree outside my office this morning. Cankerworms, like many caterpillars, produce silk from their mouths which they use, like Spiderman, to swing from tree to tree, or to drop to the ground.

When cankerworm outbreaks occur, they can produce some of the most spectacular tree defoliation events seen in this part of the country. If you have a chance to walk through an infested forest you will see millions of tiny caterpillars hanging from tree branches and blowing on the wind. After a week or two of feeding, trees can be largely stripped of leaves.

Fortunately, these outbreaks normally pose little danger to trees, especially trees in woodlots and forests. Healthy trees on good soil can usually withstand total defoliation without significant damage. Trees that lose their leaves to spring cankerworms generally re-leaf and show no signs of long-term damage. However, trees that are under stress from drought or transplantation may benefit from a timely insecticide application, before the leaves are stripped.

If treatment is needed, sprays containing Bacillus thuringiensis (Bt) or spinosad will be the safest for beneficial insects and bees. These sprays should be applied early, before the caterpillars reach their full size. If you can’t treat early, it may be best not to treat; however other insecticides, such as carbaryl, permethrin, cyfluthrin and other pyrethroid insecticides can provide effective and rapid control of all sizes of caterpillars.

Cankerworms belong to the moth family Geometridae. Spring cankerworms range in color from light green to brown. Like all geometrids, spring cankerworms have fewer than normal caterpillars. Where normal caterpillars have three to five abdominal feet, spring cankerworms have only two. The result is a distinctive looping walk, giving these caterpillars their common name “inchworm”. Click here to see a video of this walk.

Larvae (caterpillars) hatch from their egg masses in the spring when trees are reaching bud break. They grow to about one inch long and are quite slender, often with a light green stripe along their sides. When not walking, the caterpillar’s drab color blends in well with the twigs on which they rest.

Larvae typically feed for 3 to 4 weeks before dropping to the ground to pupate. Fortunately, the spring cankerworm produces only one generation a year, so ongoing spray treatments are not necessary. Both the spring, and the less common fall cankerworm, feed only on broad leaf trees and should not pose a threat to your other garden plants.

What’s all the buzz about insect hotels?

Posted on March 21, 2015 by p-porter

This creative bee hotel uses bamboo and holes of the proper sizes drilled in logs to attract solitary bees. And it’s kind of fun to look at too.

Insect pollinators seem to be receiving some overdue attention these days. Pollinator insects provide incalculable services to humans via increased fruit production and crop pollination. According to the USDA’s Natural Resource Conservation Service, 3/4 of the world’s flowering plants and about 35 percent of the world’s food crops depend on animal pollinators to reproduce.

This new interest in bees is resulting in a renaissance of a sorts in creative ideas for attracting and sheltering pollinator insects in backyards and parks and even hotels. In European hotels and hostels I’m told it’s not uncommon to see bee hotels like the one pictured here. Click here for more inspiration, but keep in mind that in Texas some of these designs will attract ants and spiders as well. If you’re OK with that fact, I think you can have some fun with this.

The idea of drilling holes in wood for bees comes from the fact that many solitary (non-stinging) bees prefer to nest in natural cavities in wood or stone. These bees, many of which are excellent pollinators, often lack good nesting sites in urban and suburban settings. By providing artificial homes for these fascinating insects, we can help conserve their numbers in our increasingly urbanized landscapes. you might even up the production of tomatoes and squash in your backyard vegetable garden.

Osmia, a species of mason bee, is a highly beneficial pollinator that can be attracted to artificial bee hotels.

I can’t go into details on how to construct these “hotels” here, but there are many good sites that do. To get inspired to start, check out the Native Bee Nest Site Project on Facebook. For a free copy of a whole book on rearing Osmia, blue mason bees–one of our prettiest and efficient native pollinators–check out the Sustainable Agriculture Research and Education site.

In the interest of full disclosure, my first attempt at creating a bee hostel last summer was not a spectacular success. I did not manage to attract any bees, though I did get some lively acrobat ants. But I am not discouraged. This summer I’m modifying my bee shelters to get better overhang on the front porch, and will try re-positioning them. South-facing nests are supposedly better, though I’m not convinced that bees in Texas are dying for more direct sunlight. I also plan to try drilling holes in wood blocks, and looking for some properly sized straws to allow me to clean out any nests that do form. Dr. Christine Casey, with the University of California, has also provided a short, but useful, fact sheet on how to build your own hotel.

By the way, if you’re still a little worried about inviting any kind of bee to your backyard, remember that solitary bees rarely sting. Besides, these interesting and active insects add immeasurably to the gardening experience. A garden without the satisfying hum of bees in the summer would be a pretty dull place indeed.

New study on bees and neonics

Posted on March 20, 2015 by p-porter

New labeling for some plants sold by The Home Depot alerts the consumer to neonicotinoid-treated plants.

Environmental groups have pressured retailers this past year to label neonicotinoid-treated plants. This Home Depot label also tells why the plant was treated.

Are insecticides to blame for killing off the honey bee? That question has stimulated lively debate in both scientific and policy circles the past two years. At the heart of the controversy is a group of insecticides known as neonicotinoids. Neonics, as they’re sometimes called, have risen over the past 20 years to become the number one class of insecticides sold worldwide, and are being used increasingly by nurseries and home gardeners to control a variety of landscape and garden pest problems.

Environmental groups contend that the case is cut and dry, namely that neonics are the reason for colony collapse disorder (CCD), a bee killing phenomenon that keeps commercial beekeepers awake at night. Yet, most bee researchers agree that the issues surrounding CCD are complex and technical, and that pesticides are certainly not the whole picture. In a newly reported study, conducted by researchers at the University of Maryland, field realistic levels of the popular neonic, imidacloprid, did not appear to have any detectable effect on bees. This despite earlier studies which showed that neonics appear to affect bees in subtle but dangerous ways.

Much of this debate about neonics has centered on what constitutes “field realistic levels” of imidacloprid and its neonic cousins. Industry representatives have contended that some recent critical studies, cited by environmentalists as justifying a ban neonicotinoids, were flawed because they were based on unrealistically high levels of the insecticides.

Maryland researchers tried to address these concerns by feeding their bees imidacloprid in protein supplement patties at doses of 5, 20, and 100 micrograms per kilogram (parts per billion). The lowest dose, 5 parts per billion, has come to be recognized as field realistic based on several studies of pesticide concentrations in the nectar and pollen of treated crops. The insecticide-laced protein supplement was provided to the bees over a continuous 12 week period. Even so this was, the authors contend, a higher exposure scenario than would likely occur in agricultural settings, where the contaminated pollen and nectar is not likely to be present continuously.

The research shows that as dosage of the insecticide in the food increases, colony survivorship decreases; however the field-realistic dose does not significantly affect key bee health indicators, including foraging, and winter survival. The major impact of higher imidacloprid exposures is increased periods when brood (bee larvae) are not produced due to weak and dying queens late in the summer. Such effects can lead to lowered overwintering survival, a character of CCD.

While not letting insecticides off the hook entirely, the authors conclude that although short term exposure to high imidacloprid levels (represented by 100 part per billion dosages in this study) does occur in agricultural settings; it is not likely to occur continuously throughout a crop cycle. Also, data from the study show that bees are efficient in metabolizing imidacloprid, so that short term spikes in insecticide levels in nectar are likely to be quickly diluted and eliminated by the bees. They conclude that while imidacloprid might be a contributing factor to some overwintering losses in bees, seed treated crops with low residue levels are likely to have negligible effects on honey bee colony health.

In the ongoing debate over bee health, I’m pretty sure this study won’t be the final word. And I doubt that the concerns of neonics critics will be wholly satisfied. In time there will be more studies done, and we will get closer to the truth about CCD and neonics.

Meanwhile, gardeners should take care when using neonicotinoid insecticides (or any insecticides) in the garden. Never treat a blooming plant with an insecticide, especially during the day when bees are foraging. By all means use alternatives to neonics when good ones exist. There are some pests (like tough scales or some borers), however, that do not have good alternatives.

Should you be concerned about buying plants in the nursery that have been treated with a neonic? Or about treating a few trees, or beds of non-blooming plants in your yard? Such applications, if done according to label directions, should pose negligible risks to bee colonies. Why? The small amounts of neonicotinoid residues in nursery seedling tissues become even more dilute as the plant grows. Furthermore, bees forage in lots of yards and fields, relatively few of which are typically treated with insecticides in urban areas. As this study suggests, small amounts of insecticide picked up from a few treated plants are likely to be quickly diluted and metabolized within a hive.

For Monarchs not all milkweeds are equal

Posted on March 5, 2015 by p-porter

Graceful and beautiful at the same time, the sight of a Monarch butterfly never fails to lift my heart. In Texas, Monarchs are harbingers of both spring and fall. In the spring, Monarchs are seen traveling north to exploit the emerging crop of milkweed plants favored by their caterpillars. In the fall, Texas serves as a flyway for southward migrating butterflies, as most of the U.S. eastern population of Monarchs heads toward their overwintering habitat in Michoacan State, in the Sierra Madre mountains west of Mexico City.

Monarchs resting in a hackberry tree on their way south to Mexico in fall.

In recent years, however, numbers of Monarch butterflies have been in decline, leading many biologists to express grave concern for the survival of Monarchs in the eastern half of the United States. In hopes of supporting the beloved Monarch, many gardeners are choosing to include a few milkweed plants in their landscape plans. The idea is that by providing Monarchs with food plants in urban areas, we might be able to provide the butterfly population a boost, and increase their numbers throughout the warm season.

But not all milkweeds, it turns out, are equally good at sustaining Monarch caterpillars. Researchers at the University of Georgia have found that the year-round blooming tropical milkweed (Asclepias curassivica) , favored by many gardeners, may be harmful to the Monarch’s traditional migration patterns. It seems that one of the benefits of migration, as exhibited by the Monarch, is that it effectively weeds out weak or diseased individuals, while at the same time removing the population temporarily from local pathogens. Tropical milkweed encourages Monarchs to stay in one spot and form sedentary (non-migratory) populations.

Dara Satterfield and her colleagues used field and laboratory studies, along with citizen scientist observations to look at relative infection rates of sedentary vs. migratory populations of Monarchs. They concluded that widespread planting of tropical milkweed, which stays green through the winter months is leading to populations of monarchs that give up their migratory behavior. They also found that disease rates were higher in these “lazy” Monarchs.

It’s unclear whether such plantings have an overall negative or positive effect on the U.S. Monarch population; but if you’re considering planting milkweed in your backyard or as part of a conservation effort, it may be best to stick with one of the many native species. For a full copy of the report click here. For information from the Xerces Society about how to select and grow milkweed for conservation purposes, click here.

Borer gets a little closer

Posted on February 20, 2015 by p-porter

Emerald ash borer adult on a penny for scale. Image: Harold Russell, Michigan State U.

What’s shiny and Godzilla green, easily fits on a penny, and has resulted in the death of tens of millions of trees over the past dozen years? If you’ve been paying attention to this blog, you might guess the emerald ash borer (EAB). Over the past few years my colleagues and I have been involved with a monitoring project designed to detect the first EAB entering north Texas. During this time I’ve watched the beetles inch closer to Texas–moving from its initial point of invasion in Michigan throughout the Ohio River valley and eventually into Missouri, Kansas and Colorado, and, last summer, in six counties in southern Arkansas.

Earlier this month, on a hunch, some zealous U.S. Forest Service employees examined a likely ash stand of 12-15 trees outside of Pineville, LA. On Feb 10, entomologist James Zablotny, emerald ash borer identification specialist for USDA, APHIS, PPQ in Romulus, Michigan, confirmed that three larvae collected from the trees were indeed EAB. The collection site was just inside the Louisiana border, about 9 miles east of Springhill, LA, in Webster Parish.

These latest finds put the EAB within 40 miles of Texas, and suggest that we in Texas may be next, if the beetle isn’t here already.

So how is this beetle with stubby wings getting so close so fast? With the help of man, no doubt. Experts believe that the most common way that this beetle finds its way across state lines is in firewood. Campers, sportsmen, or firewood vendors cut up borer-infested trees and put them on a vehicle and give the hitchhiking insects a lift.

EAB on white fringetree by Cipollini copy

Emerald ash borer larva and damage under the bark of white fringetree, a new host of this pest. Image from D. Cipollini, J of Economic Entomology, Feb 2015.

What does this mean to owners of ash trees? Since the nearest infestations are approximately 40 miles away from our state, nothing yet. However, experience from other states suggests that owners of valuable ash trees within 15 miles of a known infestation should consider proactive treatment of their trees with a labeled insecticide.

In a few weeks our office, along with entomologists from the Texas Forest Service and Sam Houston State University, will start the 2015 Texas EAB survey. This is something we’ve been doing for over five years, but this year takes on extra meaning with the threat known so close to our border.

More bad news

As if we needed more bad news, in addition to ash (trees in the genus Fraxinus), the EAB has now been found to attack white fringe tree, Chionanthus virginicus, a native tree species that is also used sometimes as an ornamental plant. In an article published in the Journal of Economic Entomology this month, Dr. Don Cipollini of Wright State University in Ohio presented the first evidence that EAB might attack other plants in addition to ash. Although fringetree is a relative of ash, the possibility exists that a few other, native plant genera closely related to Chionanthus might be susceptible to this pest.

While maybe not as destructive as Godzilla, I have no doubt we will learn to respect this pest. More on symptoms and different management options in later posts.

Getting cities ready for mosquito season

Posted on February 7, 2015 by p-porter

Knowing the basics of mosquito identification and biology is the starting point for an effective mosquito management program.

After the horrible year for West Nile virus in 2012, many Texas cities woke up to the need to devote more people and health department resources to mosquito management. To assist cities in training employees in the area of mosquito abatement, Dr. Sonja Swiger with the Texas A&M AgriLife Extension has begun offering workshops covering the basics of mosquito identification, biology and control.

This year we will have workshops in nine cities, including Dallas. Dates and links to brochures and registration information are listed below. If you work with a health department or know someone who does, consider participating in one of these programs. There is no need to be caught unaware or unprepared again.

Corpus Christi, Apr 15

Waco, Apr 21

Lubbock, Apr 30