These reddish-brown mites are cool-season mites and are active in spring and fall. They can be identified by their front legs that are about twice as long as the body and the other legs. Thousands of clover mites can invade a house through cracks in foundations or by crawling through the screens. They do not bite or sting people or pets. When crushed, they cause a blood-red spot that may stain the walls, curtains or carpets. 

Clover mites feed on the plant juices of turf grasses, clover and even certain trees or shrubs. They are more common in newly established lawns or older lawns that have been heavily fertilized. For control, caulking any cracks or opening in the foundation will help prevent mites from getting into the house. A grass-free zone of 18-24 inches around the base of the house also can be an effective barrier against mites. Landscape rocks are not effective barriers to clover mites. Some plants are not attractive to clover mites including zinnia, marigold, salvia, rose, chrysanthemum, petunia, juniper, spruce, arborvitae and yew. These plants can be planted in the grass-free zone. Insecticides registered for mite control and outside use around the house can be used as a perimeter treatment around the base of the house to reduce mite infestations. Insecticide should be sprayed 2-3 feet up the side of the house and 2-3 feet out from the base. Applications should be concentrated in the area where mites are entering the house. A vacuum or damp rag can be used to remove mites from inside the house. 

Janet J. Knodel

Extension Entomologist

janet.knodel@ndsu.edu

Adults overwinter in crevices of bark and emerge in the spring to deposit eggs in the new leaves. Nymphs hatch from the eggs and feed on the leaves causing galls to form on the underside of leaves in the summer. Most galls do not harm the health of the tree but only cause aesthetic injury. Biological control with parasitoids (wasps) is important for control, so leaving the leaves on the ground in the fall will encourage parasitoid conservation since wasps overwinter in galls in leaves. No insecticides are recommended.

Janet J. Knodel

Extension Entomologist

janet.knodel@ndsu.edu

All yellowjackets sting and their stinging behavior is considered a defensive reaction when the colony is threatened. They can sting more than once because their stinger stays with the insect. Yellowjackets are more aggressive during August into September and more likely to sting people. Although yellowjackets are actually a beneficial insect feeding on other insects, they often become a pest problem when nests are located near homes, schools, picnic areas, or playgrounds. Pest control is often warranted.

Biology:  These wasps are social insects and build nests of paper-like material. Nests generally resemble a teardrop-shaped soccer ball and often are seen hanging in trees. Sometimes nests are located underground in mammal burrows, cavities or in between house siding. In the northern temperate climates, only the mated queen wasp overwinters from the previous year’s colony. Queens are inactive during the winter, hiding in protected places like under tree barks or attics. In early spring, the overwintering queen builds a new nest and lays an egg in each cell. Larvae hatch from the eggs and are dependent on the queen for food. The queen forages outside the nest and brings food (caterpillars and other insects) back to the larvae until pupation. Sterile female workers emerge from pupae and take over nest building and brood rearing, while the queen stays in the nest. During late summer into early fall, adult males and newly produced queens leave their parent colony. The colony dies off, and only newly mated queens will find a protected place to overwinter.

Control: Vespid wasps are active outside the nest during the daylight hours. Nearly the entire colony is in the nest during the evening and night-time hours, so control measures should be applied to the nest then. There are many insecticides labeled for control of hornets and yellowjackets. The difficulty is making the treatment without being stung. Usually an aerosol spray of one of the many fast-acting wasp killer will quickly kill all workers present in nest. Examples are permethrin, synergized pyrethrins or pyrethroid insecticides. A slower-acting insecticidal approach is to apply carbaryl (Sevin) dust directly onto the exposed nest and entrance hole. After treatment, check the nest for any activity the following day and re-treat if necessary. Nests should be removed to avoid attracting dermestid beetles at some later time and to keep wasp pupae from possibly reestablishing the nest. If dealing with yellowjacket nests in structures like homes, the nest entrance should never be plugged from the outside. If constrained yellowjacket workers cannot escape to the outside, they may locate a way to escape toward the inside of the home or structure, creating a possible stinging threat for people inside. Yellowjacket nests become an important source of carpet and other dermestid beetle infestations in the home, so the nest should be removed whenever possible. When outside enjoying your picnic, avoid wearing bright colors and perfumes which are attractive to hornets and yellowjackets. 

Janet J. Knodel, Extension Entomologist

janet.knodel@ndsu.edu

Adults are reddish-brown in color and are about 8 mm long. From late May through mid-June, adults emerge from overwintered pupae and mate. Females begin laying eggs, with a single egg deposited at the base of a needle. Eggs hatch in five to ten days. Young larvae are about 5 mm long and mature larvae are almost 2 cm long and are dark glossy green with a light lateral stripe and reddish-brown head. Larvae feed for 30 to 40 days, consuming new foliage first and then older needles. Mature larvae drop to the ground to pupate. There is one generation per year.

Defoliation is caused by larval feeding. Heavily infested trees appear ragged, especially near the top, and can be completely stripped of foliage. Severe infestations over one to several years can kill trees directly or make trees susceptible to attack by other insects.

Open-grown trees that are five to nine years old are more vulnerable to yellowheaded spruce sawfly damage than are older trees or trees in dense stands. Predators, such as birds and rodents, and parasitic wasps are not always effective in keeping sawfly populations at acceptable levels. If infestations are light, larvae can be removed by hand. Isolated ornamental trees can be effectively treated by spraying off the larvae with a strong jet of water. However, chemical control often becomes necessary as the sawfly population increases. Acephate, carbaryl, imidacloprid, malathion and several pyrethroids are labeled for use against yellowheaded spruce sawfly. Biorational treatments include azadirachtin, horticultural oil, insecticidal soap, pyrethrin and spinosad.

Janet J. Knodel - Extension Entomologist

janet.knodel@ndsu.edu

It’s a Cecropia moth (Hyalophora cecropia), which is one of North America’s largest native moths. It belongs to the family Saturniidae or giant silk moths. Females can have a wingspan of 6 inches. They are found from the east coast to the Rocky Mountains and into Canada. Larvae feed on many different trees, such as maples, elms, ash, wild cherry and birch trees. Adult moths only live for about 7 to 10 days.

Janet J. Knodel - Extension Entomologist

janet.knodel@ndsu.edu

The gall is like a “house” for the developing arthropod larva. Larvae feed and secrete toxic chemicals within the plant tissues and the plant reacts by creating abnormal plant growth called galls. Although galls are not attractive, they generally do not cause significant plant mortality. Their injury is only aesthetic and chemical control is usually not necessary. There are several biological control agents, such as parasitoids that are common on galls and some can provide up to 50% mortality of galls. Shown are photos of common galls in North Dakota:  hackberry nipplegall caused by a psyllid and maple bladdergall mite caused by an eriophyid mite.

Extension Entomologist

janet.knodel@ndsu.edu

Spring cankerworms (Paleacrita vernata) belong to the inch-worm family Geometridae. They attack a variety of hardwoods including basswood, bur oak, elm, green ash, maples and white birch. There is one generation per year and they overwinter as larvae (caterpillars) in earthen chambers in soil. Larvae pupate and the spiny, wingless female emerges in early spring. Females lay masses of about 100 eggs in crevices of bark on the lower trunks of hosts. Young larvae hatch from the eggs and feed on the buds and unfolded leaves. Larvae range in color from yellow-green to almost black and have a yellow stripe along the side of the body and about ¾ to 1½ inches long when mature (Fig. 1). Another differentiating characteristic of spring cankerworm larvae is the two pairs of abdominal prolegs and a pair of tubercules on the dorsal surface of the abdomen. Larvae crawl via a looping behavior and are often blown by the wind as they hang from their own strands of silk.

Defoliation is caused by larval feeding. Repeated defoliation for three or more consecutive years will stress trees, decrease aesthetic value, and may kill tree branches.

Insecticidal treatments should be directed at the larvae in late spring or early summer. A residual insecticide sprayed on the trunk, branches and newly expanding leaves will kill the larvae as they emerge from the eggs. Spray ten days after egg hatch for the best control, but before larvae reach 1 inch long. Some active ingredients of insecticides labeled for homeowners include: carbaryl, cyfluthrin, imidacloprid, esfenvalerate and permethrin. Biorational pesticides include Bacillus thuringiensis var. kurstaki (Bt), insecticidal soap, spinosad and pyrethrin.

Janet J. Knodel & Pat Beauzay

Extension Entomology

janet.knodel@ndsu.edu

patrick.beauzay@ndsu.edu

Mosquitoes need water to complete their life cycle and the first three life stages (egg, larva, and pupa) require water for development. In the summer, mosquitoes can complete their life cycle in 7-30 days depending on species, temperature and environment. Residential areas are a major source of breeding sites. Man-made objects such as bird baths, uncovered boats, discarded tires and plant pots allow mosquitoes to breed in our own backyards. Ditches along roadways often become filled with water and are also ideal breeding sites for floodwater mosquito species. To minimize breeding sites for mosquitoes around the home:

1)       Remove standing water that has accumulated in man-made objects – tires, bird baths, uncovered boats and plant pots, anything that will hold water.

2)       Flush water out of bird baths and pet dishes at least twice a week

3)       Clean debris out of roof gutters.

4)       Correct any drainage problems in yards so rainwater will not pool in low areas.

5)       Fill tree holes with cement or sand.

6)       Swimming pools or spas should be chlorinated.  If not in use, cover. 

7)       Repair leaky faucets or air conditioning units.

8)       Keep grass and shrubs around your house well-trimmed.

For temporary relief around the yard, insecticides that target adult mosquitoes can be sprayed a few hours or a day before a picnic or other event. However, these measures only provide temporary relief because mosquitoes can move long distances of 20 or more miles. Outdoor foggers usually only provide about 3 hours of relief before the chemical dissipates and mosquitoes return. Spraying trees or shrubs, and long grass where adult mosquitoes are resting may help reduce local mosquito populations. Numerous insecticides are available for the homeowner, such as, Tempo, Demand CS, or Sevin.

Home owners can treat small water areas, such as bird baths, garden pools, etc., by using a bacterial insecticide. These insecticide products are known as “dunks” (or “donuts”) and are available at many retail stores, garden centers and on-line garden suppliers. Dunks contain a granule that contains the bacterium Bacillus thuringiensis israelensis or "Bti". This bacterium kills mosquitoes, but does not harm fish, birds or other wildlife. The "dunk" versions are well-suited for small breeding sites (100 sq. ft. or less) and will control mosquito larvae for about 30 days. Before using Bti products, it is a good idea to understand the life cycle and habitat requirements of mosquitoes in your area. Simply treating all areas of standing water without knowing if they are actually sources of the problem is a waste of time and money.

Again, the best long-term solution to severe mosquito problems is to modify or eliminate breeding sites.

For protection against mosquito bites and diseases that they vector (such as West Nile Virus) follow these guidelines:

1)       Wear long pants and long-sleeved shirts and earth-tone color clothing (light brown, olive, khaki).

2)       Use mosquito repellent containing DEET, picaridin, or oil of lemon eucalyptus (biopesticide).

3)       Fix holes in screen windows and doors to prevent mosquitoes from getting indoors.

4)       Stay indoors at dawn and dusk when mosquitoes are most active.

5)       If you are planning an outdoor picnic or activity, spray trees and shrubs with ready-to-use insecticide sprays, aerosols or foggers the day before your activity. Always read and follow the pesticide label.

Additional mosquito information is available at the website for the Centers for Disease Control and Prevention.

http://www.cdc.gov/ncidod/dvbid/westnile/index.htm

Janet J. Knodel - Extension Entomologist

janet.knodel@ndsu.edu

For example, ticks can transmit Rocky Mountain spotted fever and Lyme disease, and mosquitoes can transmit West Nile virus. The main question consumers have is how to find a product that can prevent you from being bitten and is safe to use. Mosquitoes and ticks are attracted to us by our odors and carbon dioxide from breathing. Most repellents work by masking the chemical cues and making you unattractive for feeding. Unfortunately, they only work at a short distance and do not kill their insect target. So, even when you have repellent on, you can still see mosquitoes whining in your ear and flying around nearby. Repellents are available as sprays, wipes, sticks, foams and lotions. It is important to select the ‘right’ repellent for your activity (exercising or relaxing), weather (hot and humid, or cool and dry), and the amount of time that you plan to be outdoors. The EPA has a website to help you choose the repellent product that is right for you at:  http://cfpub.epa.gov/oppref/insect/index.cfm

Some popular repellents are: DEET (or N,N-diethyl-m-toluamidae or N,N-diemethylbenzamide), Picaridin (KBR 3023), oil of lemon eucalyptus, and IR3535. DEET and Picaridin are both synthetic repellents, whereas oil of lemon eucalyptus and IR3535 are biopesticide repellents (derived from natural materials). In general, the more active ingredient in a repellent corresponds to a longer period of protection from bites. However, shorter protection time does not necessarily mean less protection, just less time. In Table 1, the protection times of tested mosquito’s repellents are listed and range from 5 hours to 0 (Source: University of Florida, IFAS Extension). When using repellent, apply enough to cover exposed skin or clothing. Avoid apply repellent to skin under the clothing and to cuts, wounds or irritated skin. Some people may be allergic to ingredients in the repellent. Use common sense when applying products and read the label first! The EPA has ruled that normal use of DEET is not a human health concern.

Besides repellents, clothing is important and netting can be used to deter biting insects, such as mosquitoes. Some outdoor manufacturers, such as L.L Bean, also make “Buzz Off” clothing with Permanone-treated fabric as an alternative to topical repellents. Permethrin is the active ingredient in Permanone, which is safe for humans according to the EPA. Buzz Off clothing is effective in repelling insect for 25 washings. 

Other common topical products on the market combines repellents and sunscreen. However, the Center of Disease Control (CDC) does not recommend using combined products with both repellent and sunscreen. Blending these two products decrease their efficacy due to lower amounts of active ingredients. Also, this may increase your exposure to the insect repellent since you may need to reapply more frequently. The CDC recommends applying sunscreen first and then the insect repellent.

There are several devices that don’t work as bug repellents, such as devices that emit sound to repel mosquitoes or ticks. Eating garlic, vitamin-B, onions or any other foods will not make a person less attractive to mosquitoes either. Don’t use traditional electric bug zappers. They attract many other insects, often beneficial insects, but mosquitoes largely ignore them. The newer portable traps (Mosquito Deleto from Coleman Company or Mosquito Magnet from American Biophysics Corp.) emit carbon dioxide and a chemical called octenol, which lures mosquitoes away from people. However, it is unknown whether these traps reduce the number of bites to people nearby. Citronella candles have been used since 1882 to repel mosquitoes, but research has shown that they are no more effective than plain candles, which give off heat, carbon dioxide and moisture.

Proper and safe use of insect repellent will help make your summers more enjoyable when working or playing outdoors!

 Janet J. Knodel

Extension Entomologist

janet.knodel@ndsu.edu

Digger bees prefer to infest areas of the lawn with sparse grass from drought conditions or tree shade. Although these bees are often blamed for causing the unhealthy lawn, digger bees do not damage a healthy lawn.

Digger bees have one generation a year. They overwinter as larvae in the underground cells. In the spring, digger bees pupate and emerge as adults. The female creates the nest in the ground and collects pollen, packing it into the chamber. Then, eggs are laid in the pollen-packed cell, and larvae feed and develop for the rest of the summer and over the winter. Males are not involved with nest construction or provisioning, and spend their time cruising over the nesting area for a chance to mate. Adult bees only live for about 4 weeks and then are not seen again until next spring. Digger bees are solitary bees and each hole is one bee’s nest. In contrast, honey bees are social bees with a queen bee and many worker bees in one nest.

Fortunately, digger bees are docile and not very aggressive. They typically do not sting unless trapped or handled. Still, large numbers of active bees swarming over an area of lawn can be distressing for homeowners. For management, homeowners can try watering, mulching or planting shade tolerant grass in the area to make it a less favorable habitat for digger bees. Insecticides are recommended as the last resort, since digger bees are valuable native pollinators which pollinate our trees, shrubs and flowers. Homeowners can use powder or liquid formulations of insecticide, and dust or spray into the entrance of the burrow. Some suggested insecticides include Sevin® (carbaryl), Tempo® (cyfluthrin), or any other insecticides registered for wasps and outside use in lawns. Please be certain that you are not dealing with other bees or wasps (hornets) that are very aggressive and harmful. They can quickly attack you in large numbers and cover you with stings! You may want to hire a professional pest control company for those aggressive insects.

 Janet J. Knodel - Extension Entomologist

janet.knodel@ndsu.edu