Blister Beetles - What Hay Producers and Buyers Need to Know
By Lee Townsend

Here are some key points about blister beetles –

• Blister beetles occur throughout the US – they are a potential problem in most all hay-production areas but risk varies greatly from area to area and year to year.

• Blister beetle toxicity is caused by cantharidin, a defensive compound that occurs in male blister beetles and is transferred to females during mating. If sufficient numbers of live or dead beetles are consumed, cantharidin irritates the intestinal and urinary tract and can lead to animal death, especially in horses.

• In Kentucky, blister beetles are active from mid-July into early September. They tend to cluster together, especially on flowering plants.

• Clear steps can be taken to eliminate or greatly reduce the potential of blister beetles in hay – 1) Use hay for horses that is cut before blister beetles become active; 2) if practical, cut hay before alfalfa or common flowering plants in the field are in bloom; 3) do not crimp condition hay if many plants are in the bloom stage.

Blister beetles feed on a wide range of plants including alfalfa, clover, soybean, potato, tomato, and eggplant and are especially attracted to flowers. Like the Japanese beetle, feeding by a few blister beetles draws in more. Large numbers of beetles can cluster on small patches of flowering plants in an otherwise uninfested field. This can result in infested hay.

Fields should be checked visually for blister beetles before harvest. Especially flowering plants along field margins should be inspected. Sickle bar mowers and some circular or rotary mowers lay the hay down without crushing many beetles. As the hay cures, the beetles will leave.

Blister beetles have long (3/4" to 1-1/4"), narrow bodies, broad heads, and antennae that are about 1/3 the length of the entire body. The segment behind the head is narrow, so the beetle appears to have a "neck". The front wings are soft and flexible in contrast to the hard front wings of most beetles. The black blister beetle (jet black) and the margined blister beetle (black with thin gray stripe around wing covers) are common species in Kentucky.

Female blister beetles lay clusters of eggs in the soil in late summer. The small, active larvae that hatch from these eggs crawl over the soil surface entering cracks in search for grasshopper egg pods which are deposited in the soil. After finding the egg mass, blister beetle larvae become immobile and spend the rest of their developmental time as legless grubs. Blister beetles will not lay eggs in hay and the larvae do not feed on or develop in hay bales.

With the abundance of warmth and moisture, mosquito season is in full swing throughout the Commonwealth. Mosquitoes are a perennial nuisance for which there is no easy answer. As summer continues, there will be lots of information (both good and bad) about what works and what doesn’t.  The following measures can afford some relief.  

Eliminate Breeding Sites – Mosquitoes need quiet, non-flowing water for their development and periodic summer storms provide just such conditions. Eliminating large sources of standing water may require community-wide effort.  Nonetheless, homeowners can take steps to prevent mosquitoes from breeding on their property:

1. Dispose of old tires, buckets, aluminum cans, plastic sheeting or other refuse that can hold water. Empty accumulated water from trashcans, boats, wheelbarrows, pet dishes, and flowerpot bottoms, and if possible turn them over when not in use. 

2. Clean debris from rain gutters and unclog obstructed down spouts. Clogged or damaged rain gutters are one of the most overlooked mosquito breeding sites around homes. 

3. Change water in birdbaths and wading pools at least weekly, and keep swimming pools clean, chlorinated or covered when not in use. Ornamental pools can be aerated or stocked with mosquito-eating fish. Aeration and water movement helps because mosquitoes prefer quiet, non-flowing water for egg laying and development.  

4. Fill or drain ditches, swampy areas, and other soil depressions and remove, drain or fill tree holes and stumps with mortar to prevent water accumulation. Eliminate standing water and seepage around animal watering troughs, cisterns, and septic tanks. Be sure cistern screens are intact and access covers fit tightly.

Larval Control - Use of a mosquito larvicide can be beneficial when it is impractical to eliminate a breeding site. Larvicides are insecticides used to control immature mosquitoes before they have a chance to develop into biting adults. Most larvicides sold to homeowners contain either the ingredient methoprene, or the bacterium Bacillus thuringiensis israelensis (Bti). Neither active ingredient is harmful to fish, waterfowl, pets or humans when used according to label directions. Many products and formulations containing methoprene (Altosid®) and Bti (Bactimos®, Vectobac®) are used by mosquito abatement agencies and other professionals. Homeowners can purchase the methoprene-based larvicide, PreStrike™ in hardware stores. PreStrike is formulated as a granule and comes in a shaker bottle. Various products containing the mosquito- specific bacterium, Bti, are also sold to homeowners.  Mosquito Dunks® and Quick Kill® Mosquito Granules, for example, can be found at hardware and discount stores. 

Adult Control - Adult mosquitoes prefer to rest in moist, shady areas such as dense vegetation during the daytime. Consequently, homeowners should remove tall weeds and overgrown vegetation from their yards. To further reduce intolerable levels of biting adult mosquitoes, residual insecticides can be applied to shrubs, hedges and other shaded areas, such as under decks and along foundations. Research by University of Kentucky entomologists indicates that such treatments effectively suppress nuisance, biting mosquitoes for about a month. Residual mosquito sprays are often best applied by professional pest control firms. Homeowners opting to try this themselves should use lawn and garden insecticides containing permethrin (e.g., Ortho Mosquito B Gone, Spectracide Mosquito Stop), cyfluthrin (Bayer Advanced Powerforce Mosquito Killer), bifenthrin (e.g., Ortho Home Defense Max), or lambda cyhalothrin (Spectracide Triazicide). For homeowners, a hose-end sprayer is usually most effective for making such applications. 

Exclusion - Mosquitoes can be kept out of homes by securely screening windows, doors and porches.  The occasional mosquito found indoors can be eliminated with a fly swatter. Aerosol-type insecticides labeled for mosquitoes, gnats, and other flying insects seldom provide much relief at the dosages applied by householders.

Topically-Applied Repellents - Repellents will help prevent bites when spending time outdoors.  Traditionally, the most effective mosquito repellents contained the active ingredient diethyl toluamide (DEET) ranging from 5% to 40%.  Higher percentages of DEET in the ingredients provide longer protection. Low -percentage formulations (10% or less) are suitable for shorter periods outdoors (e.g., a few hours), and are recommended for use with young children. Recently, two additional mosquito repellent ingredients were registered by the U.S. Environmental Protection Agency and recommended as alternatives to DEET by the Centers for Disease Control and Prevention. Picaridin (7% Cutter Advanced) and Lemon eucalyptus oil (30% Repel Lemon Eucalyptus) provide relief for about 2 to 4 hrs, particularly when insect biting activity is not too severe. Unlike DEET-based repellents, Picaridin is essentially odorless and Lemon eucalyptus oil has a lemon scent. For many people, the new products will also have a more pleasing feel on the skin. With a little hunting, both repellents can be found on store shelves. Always read and follow directions on the container. 

Other Control Possibilities - Many consumer products claim to attract, repel, capture or kill mosquitoes. Most of these devices do not appreciably reduce mosquito abundance or incidence of bites, or else their claims are unproven. Electrocuting devices or "bug zappers" using ultraviolet light as an attractant are generally ineffective in reducing outdoor populations of mosquitoes and their biting activity. Studies indicate that mosquitoes make up only a tiny percentage of the insects captured in such traps. The majority are moths, beetles and other harmless night flying insects. Other types of mosquito traps utilize carbon dioxide, warmth, light, and various chemicals (e.g. octenol) as attractants and claim to capture tremendous numbers of adult mosquitoes.  Such devices can be quite expensive. Performance claims to the contrary, such traps seldom have been shown to reduce populations of biting mosquitoes on one's property, or the frequency of bites. In some situations, they could even attract more mosquitoes into the area they were meant to protect.      

Advertisements for portable electronic devices using high frequency, ultrasonic sound routinely appear in magazines, claiming to keep mosquitoes and other pests at bay. Some supposedly repel mosquitoes by mimicking the wing beat frequency of a hungry dragonfly. Scientific studies have repeatedly shown these devices to be of negligible benefit in deterring mosquitoes and reducing bites. Save your money, as these devices seldom if ever provide any appreciable measure of protection.

Citronella oil does have mosquito-repelling properties and the scented candles can provide some protection. For maximum effect, use multiple candles placed close (within a few feet) of where people are sitting. A single candle located at the center or edge of a picnic blanket probably will not provide much benefit other than atmosphere. Mosquito-repellent plants, garlic, and other oft-advertised botanical products generally are ineffective.

Bats and certain types of birds (e.g. purple martins) are often cited as effective natural agents for managing outdoor mosquitoes. Conservation groups and nature magazines often suggest building bat and birdhouses on one's property to promote nesting and to protect against mosquitoes. Although insectivorous bats and birds do eat mosquitoes, they make up only a very small portion of their natural diet. Much like the mechanical "bug zappers," bats and birds capture all manner of other flying insects also. Efforts to colonize and conserve these animals should not be done with the primary intent of diminishing biting mosquitoes.

When it comes to managing mosquitoes, a good rule of thumb is if the approach or device sounds too good to be true — it probably is.

Swimming pools attract a variety of insects. Honey bees come to collect water for use in their colonies. A few aquatic insects, mostly bugs and beetles, come because water is their natural environment; to them, a swimming pool is just another pond. A few (like thrips) come as a result of disturbances – cutting hay fields or wheat. Finally, there are those that just accidentally fall into the water and cannot escape.

Honey bees need lots of water to maintain optimum hive temperature and humidity; a nearby swimming pool may be the most convenient supply, causing alarm to pool owners and users. Worker bees that find a good water source will recruit colony mates to join them. Over time, hundreds of bees may be appear. Some will fall into the water and drown but others will keep coming. They are preoccupied with this task and generally are not a threat. Dealing with bee visits to small kiddy pools can be as simple as moving the pool to a different spot in the yard every few days. Bees follow directions very strictly and if the pool is not where it should be, they will not find it easily. You can stay ahead of them with the moves.

Aquatic insects, such as backswimmer bugs and toe biters, may arrive in large numbers as they fly from ponds in which they developed to colonize other bodies of standing water. In some cases, they may be abundant enough to clog filtering systems. Usually, this mass movement lasts only a few days. Backswimmers are predators; they can give a painful bite with their piercing-sucking mouthparts. There should be no question as to what the toe biter can do. The pain from these bites is similar to a bee sting but there is no toxin.



Figure 9. Backswimmer with oar-lik hind legs.



Figure 10. Giant water bug - toe biter.

Thrips can make a dramatic appearance. These tiny elongate yellow insects were described on one insect ID form as follows: "These little biting things covered an aboveground pool and deck. They were so thick that you could wipe them off with your hand. They have painful bites, children could not play in the pool for them."
 
Thrips show up at pools probably drawn to water or driven there from nearby recently-cut hay fields. On normal days thrips use their abrasive mouthparts to rasp at plant tissue, especially flowers. However, they will scrape skin, perhaps as they attempt to pick up small amounts of moisture. An occasional thrips scrape probably is tolerable but lots of them do not add to the swimming experience. A strong jet of water may be used to plaster them to decks and other surfaces where they have accumulated. Finding and managing the source of an insect problem usually is the most effective management practice but this is rarely possible or practical with swimming pool invaders. There is no safe or effective means of treating pool water to keep intentional or accidental invaders away. Covering the pool when it is not in use may be the best and only way to exclude chronic problems with unwanted creatures. Fortunately, this may be needed for only a few days at a time. The clumsy pool invaders are the easiest to handle – the few that fall in can be removed with a cleaning net or cup.