Mosquitoes Take a Bite Out of Summer Gardening

Mosquitoes are easy to recognize by sight, sound or feel. Of course, they are not a garden pest because of any damage to plants. Their damage is a much more personal annoyance to the gardener.

Mosquitoes are best known because of the blood-sucking habits of the females. Males do not feed on blood, but live solely on nectar from flowers or moisture from other sources. The females require blood in order to develop eggs. The blood can come from a variety of animals, depending on the species of mosquito.

Mosquitoes come from larvae that live in standing water in ponds, pools and puddles or buckets, barrels and birdbaths. The larvae are called wrigglers because of their swimming action as they feed on algae and organic debris. Larvae live for 7 to 10 days and then change into a pupa or "tumbler" that lasts for another 2 or 3 days.

Each new generation of mosquitoes can appear in as few as 10 days. Large populations develop quickly when periodic summer rainfalls keep water impoundments full, leading to the miserable mosquito situation we have now.

Wishful Thinking
There is very little that an individual can do to change mosquito populations in a significant way. Most home garden control actions taken against mosquitoes amount to wishful thinking, largely because of mosquito dispersal. While some species of mosquitoes remain near the water where they developed, others may travel distances of up to a mile or more during their adult life span of approximately 2 to 3 weeks.

Prevention of mosquito breeding in your garden or landscape is desirable, even though it won¹t solve your mosquito problems. Remove old tires, buckets and other water-holding containers. Change the water in the bird bath and wading pool at least once a week and clean out or repair roof gutters so that water does not accumulate. Drain or fill puddles or ditches that hold water for long periods of time.

Fogging or spraying the backyard and garden for control of adult mosquitoes may provide relief for a few hours or less. Residual sprays can be applied to tall grasses, weeds and shrubs to reduce adult populations. The larger the area treated, the better the control, but even the best results are likely to be short-lived.

More Wishful Thinking
Some of the least effective mosquito controls are the simplest to use. For example, light trap insect electrocutors are easy to install but are worthless.

"Bug zappers" have been extensively marketed for many years with claims they can provide relief from the annoyance of biting mosquitoes and other pests in your backyard. However, their effectiveness has been widely disproved by studies that have shown they fail to kill mosquito females.

Also worthless are the so-called mosquito repellent plants such as scented geraniums and citronella grass. These "miracle plants" do contain citronella oil, but growing the plants has absolutely no effect against mosquitoes. Significant amounts of repellent oils can be released when the leaves are crushed, but rubbing the crushed leaves on your skin is risky because of allergy or irritation.

Citronella candles, like scented geraniums, can be a welcome aesthetic addition to your garden or patio decor or ambiance, but the effectiveness of candles in keeping away mosquitoes is again, wishful thinking. Any light breeze will disperse the repellent and sufficient concentrations of repellent are only likely to accumulate immediately next to the candle under calm conditions.

What Does Work
The one mosquito coping technique likely to work for most gardeners most of the time is application of personal repellent to exposed skin and clothing. There are several repellents to choose from, including commercial products and home remedies and everyone seems to have his or her own favorite. The best mosquito repellent is the one that works for you and that may be different from the one that works for someone else.

Most repellent products contain DEET, the abbreviated name for N, N-diethyl-meta-toluamide, a repellent developed approximately 40 years ago and still the most effective repellent available. Research reported by Consumer Reports magazine three years ago found that a 40 percent DEET aerosol "warded off mosquitoes for more than six hours." Products of 20 to 40 percent DEET were nearly as good and protected for up to four hours. Sparing use of the lower concentration products is adequate most of the time.

"Natural" repellents that contain citronella or a mixture of citronella, cajuput grass, sassafras, peppermint, myrrh, vanilla and other ingredients seem to work for some people, though their performance in research has been poor. Avon's Skin-So-Soft bath oil and hand cream, alternatives that have garnered a large number of testimonials, contain isopropyl palmitate, one of several known mild repellents. Effectiveness is highly variable but usually short-lived, often as short as 15 minutes.

When using any repellent, don't apply near eyes, on lips or on broken skin; avoid breathing spray, don't use near food and wash repellent off with soap and water when it's no longer needed.

Yellowjacket Nests in Houses

If you have "bees" going in and out of the wall of your house, you probably have yellowjackets.

Yellowjackets are elongate, about 1/2 inch long and are black with yellow markings showing as stripes on the abdomen. These wasps construct large paper nests underground, in wall voids and in other protected places. They contain several horizontal combs and several thousand individuals.

All members of the nest, except the "queen," die during the winter and new ones are started each summer by fertilized females that overwinter in protected places.

The young yellowjackets (larvae) feed on insects and other bits of meat that the adults capture or scavenge from garbage cans, picnics or other areas where food is left uncovered. The adults chew up the insects or other meat and feed this partially digested food to the larvae. Adults feed on nectar and the juices of the larval food.

Elimination of nests is best done at night when the yellowjackets are less active. Be sure to wear protective clothing in order to minimize exposed skin to possible stings.

Underground nests will usually have a single opening that the wasps use to enter and leave the nest. Ground nests can be treated by soaking the nest opening with Diazinon. Seal the opening with soil immediately after spraying.

Wall void nests are frequently several feet from the wall opening that wasps use to enter and leave the nest. Thus, direct insecticide spraying involves the removal of part of the wall.

These wall void nests can also be killed by placing carbaryl (Sevin) dust in and around the wall opening. The yellowjackets pick up this dust on their bodies, groom themselves with their mouth parts and feed each other in the nest. Frequently, the insecticide dust must be reapplied up to four times over a two week period.

Once the wasps have been killed, a few more may emerge from cocoons over the next few days, but these are likely to encounter the insecticide dust and die also. Since the source of reproduction, the queen, has been killed, no more young will be produced. After two weeks have passed with no wasp activity near the nest opening, the hole may be sealed.

Caution! Do not confuse yellowjackets with bald-faced hornets, bees and beneficial wasps. These insects are considered friends of man, because they feed flies and other harmful insects to their young and pollinate plants in the process of gathering nectar to feed themselves. Their nests should be allowed to survive in most situations.

If one stays at least three or four feet away from the nest, hornets will usually not attack. Lawn work and other necessary activities close to the nest should be done late in the evening, when hornets are less active. Rarely will hornets sting while foraging for food.

Annual Grub

Annual white grub adults are in full emergence throughout the state. Unless you are using imidicloprid (Merit, Grubex), treatment should be delayed until late July in southern Illinois and early August in central and northern Illinois. Imidicloprid treatments should be applied now, if needed.

Late Summer 1996
Cover Crops | Tomato Problems | Annual White Grub Homeowner Control Options | Phalaenopsis: "No Better Orchid for Beginners" | Bug Bites | Lawn Care Calendar | To A Violet | Hort Shorts | Hort Tips | OTC Hearburn Drug | Food Safety Checklist |Healthy Cooking: Cabbage | Nutrition Facts: Meal Planning 101 (Part 3 of 3) | Health and Household Tips | Did You Know?

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