A Bug Lady's Observations at Vancouver's Compost Demonstration Garden
Ursula Dole of GREENBUG Biological Pest Control Inc., will be spending the last Saturday of every month this year at our demonstration garden in Vancouver. On this web page, she will share with you her observations. You can also visit her at the garden at 2150 Maple Street, (corner of 6th and Maple), or call 604-736-2250. Bring your pests (in a jar) and your questions.
The Greenbug Guide to a Totally Organic Garden - BC EditionFor further bug information, visit these three resources:
By Ursula Dole and Diane VanKirk
Published by Greenbug Biological Pest Control, 1998
- Integrated Pest Management Manual for Home and Garden Pests in British Columbia
- Seattle's Integrated Pest Management Fact Sheets
- Pesticide-Free Solutions from the Northwest Coalition for Alternatives to Pesticides
October 29, 2005
Aah, the last Saturday of October and Halloween weekend to boot. So, what else would I write about but spiders. Spiders, my favorite arthropods, often strike fear into the hearts of otherwise well adjusted individuals. The reasons for this fear may differ from one person to the next, but the reactions are pretty much the same, namely a shriek accompanied by a shudder and a running leap to safety or a weapon. Should the spider survive such an encounter with a human, it is probably scarred for life.
Spiders (Order: Araneae) are the largest group of arachnids, with some 35,000 species named so far. These familiar predators can be found on the ground, under rocks, among grasses, on plants, in trees, in caves, in or on the water, in basements, in bathtubs, in kitchen sinks, well, the list goes on. Spiders are easily recognized by their eight legs and body consisting of two distinct parts; the cephalothorax and abdomen. Most spiders have eight simple eyes, although some have less or none. Below the eyes are two jaws (chelicerae) which end in fangs. Venom is produced on glands and empties through a duct in the fangs. The venom is used to kill or paralyze prey. The majority of spiders pose no threat to humans as their venom is not potent enough and their fangs cannot penetrate our skin.
One of the more visible spiders is the garden or "cross" spider (Araneus diadematus) which spins its web across almost any gap, including door ways and open windows. The spider gets its name from the cross-like pattern of silvery spots on the abdomen. The spider usually rests head downward in the center of the web or at the end of a single thread, waiting for flying or jumping insects to get stuck in the web. Females are larger than the males and attach egg masses to a leaf, twig, or other structures at the side of the web. The spiderlings usually stay in the egg sac until the first molt, after which they disperse either by ballooning or just walking away. Ballooning is the process by which spiderlings, and in some species adult males release long silken strands, which they use like parachutes to ride the wind to other areas.
Other common spiders are the wolf spiders which actively hunt insects either by sight or through the feel of vibrations and do not produce a web. Wolf spiders often enter houses through open doors and windows and can be seen wandering across the floor or trapped in the bathtub, the latter being the reason for the myth that they come up the drain. Also sight orientated hunters, jumping spiders jump on their prey - either insects or other spiders. They, too, do not weave a web, but can be observed trailing an anchoring silk thread. Most spiders are opportunistic predators, which means they do not have a specific prey, but will eat whatever they can catch. Overall spiders are important insect pest control agents and should be encouraged in the garden.
Some spiders which are encountered almost exclusively in buildings belong to the genus Tegenaria. The barn funnel weaver (Tegenaria domestica) is the most common one and constructs a sheet-like web in a dark corner. The hobo spider (T.agrestis), whose bite is quite painful also builds a sheet-like web, but this can be found in cracks and crevices close to the ground or higher up, eg. around window sills, as long as there is a dark place to hide. And then there is the giant house spider (T. gigantea), which by some people is considered the least attractive of spiders. The male in particular can cause a panic when he runs across the living room floor with his long, bristly and spindly legs flailing about every which way.
The most feared spider in British Columbia is the black widow (Latrodectus hesperus), but she is also the most recognizable spider with her shiny black body and red hour glass (or two red triangles) on the underside of the abdomen. This spider's venom can indeed be deadly, but she usually is not very aggressive unless disturbed. Black widows can often be found in outhouses, wood piles and abandoned mammal burrows, but also in grocery stores, having been transported with the fruit and vegetables. The female will eat the mate after mating, if possible, but that is not a trait unique to black widows; females of other species do it as well.
Spiders vary considerably in size. The largest of all spiders is the goliath tarantula of South America with a leg span of 25 cm. The smallest fully grown spider is the male of a species called Patu digua which has a body length of just 0.37 mm. Apart from size, spiders differ greatly in appearance. While some are brightly colored, others are very inconspicuous. Some are fat-bodied, others resemble worms, and many are bizarrely decorated with strange surface features.
Spiders avoid danger in a number of ways. Many have impenetrable hiding places, others use color for concealment. For example, green spiders live among leaves, while yellow, red, or white ones hide among flowers. Some are beautifully camouflaged against backgrounds like lichens or bark, and others go unrecognized because they mimic ants - insects which just about everybody avoids.
Despite the fact that a lot of people find spiders ugly and disgusting, the truth remains that they are beneficial and play an important part in the ecology of the plant by helping to control harmful insects and policing their own populations.
September 24, 2005
Today is the last Saturday in September and I was observing the yellowjackets and other wasps in the garden. I am always amazed how many different wasp species can inhabit a pesticide-free garden, many of which may never be noticed by the casual onlooker. Some of these are the beneficial parasitic wasps which lay their eggs in or on their hosts, like aphids or the eggs and caterpillars of butterflies and moths. The wasps can be very small and inconspicuous or large and colorful. Ichneumon wasps, for instance, are often fairly large and slender, with the part of the abdomen attached to the thorax elongated and severely constricted. The females usually possess a long and conspicuous ovipositor. The larvae of ichneumonids are parasites of caterpillars, beetles and other wasps. Parasitic wasps live solitary lives, while the more commonly known yellowjacket (12 - 16 mm, black with yellow or white stripes) and baldfaced hornet (16 - 20 mm, body black, white pattern on face) are social insects, whose colonies consist of a fertile queen, infertile female workers and males, the latter appearing in early fall. At the end of the season (mid to late fall), rearing slows and colonies begin to break up. All workers and males die, only the fertilized females survive. These future queens disperse and find shelter in protected sites. The nests are left and not reused.
Yellowjackets can be quite aggressive and may sting without much provocation. Their nests are often hidden and, therefore, easily disturbed. In spring and early to mid summer the wasps diet mainly consists of live and dead insects and other invertebrates, while in late summer and early fall fruit, rotting or not, is a major source of food. Baldfaced hornets feed on live insects throughout the season, making them pest control agents in the garden. For the most part they only sting when their nest is threatened. This is often avoidable since the conspicuous paper nests are built free-hanging on branches of trees and bushes or under overhangs and eaves.
Because yellowjackets are scavengers they are attracted to more diverse sources of protein and sugar than just insects and fruit. So, when you are sitting down in your garden to a nice picnic consisting of at least one of the major food groups, chances are that you will have some uninvited guests. Here are some tricks that might help you to enjoy the outdoors a little more. Starting in early spring, before yellowjackets start looking for a nesting site, hang brown paper bags, filled with paper and shaped like gourds, around your yard, patio or balcony. These gourds look like hornet nests to yellowjackets and, therefore, pose a threat. Baldfaced hornets have been observed attacking yellowjackets. They do this either, because they consider yellowjackets competetion for food or may see them as prey. Since yellowjackets are attracted to protein, dead or alive, a bit of moist cat food placed out of the way of your eating area may just be enough temptation for the wasps to change their flight path to that location. Should the wasps insist on sharing your meal you might want to consider removing some of it to the side and letting them have it. The worst you can do is to slap at them, especially if you are allergic to their sting, because that only makes the wasps madder and more aggressive. Also be aware that yellowjackets are attracted to shiny objects like cutlery, rings, ear rings and necklaces, sweat, flowery perfumes, deodorants and hair products. If at all possible wear light clothing during your outdoor meals.
The nests of yellowjackets are often located in attics, under eaves, hidden in walls, dense hedges or the ground. If you need to remove the nest, which may contain several thousand individuals, I would strongly suggest to let a professional all natural pest control company take care of that, otherwise the consequences could be unpleasant, to say the least. Once, I located a sizable nest in an attic. But instead of turning my flashlight off after I knew where they were, I kept shining the light on them. This seemed to annoy them. As a matter of fact, I know it did, because all of a sudden a loud buzzing noise could be heard and several hundred wasps (well, 20 or 30 at least) came toward me. I dropped the light and, literally, dove out of the door, kicking it shut behind me. I had no idea I could move that fast. So, the lesson to be learned here is: if you suspect a yellowjacket nest in an dark area, let somebody else check it out, preferably a professional with the proper equipment and clothing.
August 28, 2005
Today's topic of my bug report is the importance of pollinators in the garden. It is often mistakenly assumed that honey bees are the only pollinators of any significance. While honey bees play an important role in the pollination of plants, particularly crops, other insects, including several members of the different bee families, are equally well equipped for this task.
Some of the more obvious ones are bumble bees, which like honey bees, are social insects with a well defined cast system, consisting of a queen, sterile female workers and drones (males). Golden northern bumble bees and red-tailed bumble bees can often be observed visiting many flowers in the garden and, thereby, distributing pollen. The pollen clings to the hairs on their bodies and is stored for transportation back to the nest in special pollen baskets on their hind legs from where it rubs off onto the reproductive organs of the flowers.
A pollen collection apparatus is not unique to honey bees or bumble bees. Plasterer bees, yellow-faced bees, green metallic bees, mason bees, digger bees and mining bees, just to name a few, are also equipped with such a device and are important pollinators. Some of these bees are solitary while others are social or communal, but all may be present in a garden with a high rate of plant diversity.
Members of different wasp and fly families contribute to the pollination process as well. Yellow jackets, for instance, are not only beneficial as insect predators, but also as pollinators during their search for nectar. Hover flies (syrphid flies) are also unsung pollinators. While the larvae prey on aphids, the adults drink nectar and, thereby, transfer pollen from flower to flower. Because butterflies also feed on nectar they pollinate flowers in their quest for food. Even ants which farm aphids can transport pollen from one flower to the next.
To attract as many different pollinators as possible to the garden, it is important to have the right kind of plants. The more heterogenous a garden is the more beneficial insects can be found. Pollinators, predators and parasitoids are attracted to gardens with a mix of tall and short plants, large and small flowering plants and flowers of different colors. Interplanting and companion planting practices help keep your garden healthy and relatively low maintenance with no need for chemical pesticides. Since most pesticides are broad-spectrum they kill all insects, including pollinators, predators and parasitoids. So, enjoy your garden's biodiversity and watch the many different pollinators do their thing.
July 30, 2005
Here we are again. Its the last Saturday of the month and time for my bug report. Today I will write a bit about ants. Out of the 4 or 5 species of ants you might encounter in or around your home and garden, pavement ants may just be the most annoying. They are the ones that excavate soil and sand from in between pavement stones, bricks, along wall - in short pretty much anywhere they can. Not only are the results of this practice unsightly, they can also lead to structural damage.
Now the question is: How can you control them? Well, that takes some effort and commitment. Pavement ants are attracted to oily or sugary foods, so the bait should be formulated accordingly. You might want to mix equal parts of 2% boric acid (granular eyewash available in drugstores) with peanut butter or icing sugar. These mixtures should be spread along the ant's pathways and in and around entry/exit holes. This is not a one shot solution. The treatment needs to be applied every 5 to 7 days until the ants have disappeared.
But be aware that as soon as one nest has been destroyed another pavement ant colony may move in and the process starts again. Both types of baits can be toxic to dogs and other animals, depending on the amount applied. Always keep pets and children away from any insecticide, all natural or otherwise. I have lots of pavement ant colonies in my brick patio. Normally I leave them be, but this year they were just too numerous and annoying, especially when some of the colonies co-habited with carpenter ants. This happened where the brick borders on cedar planks that, unbeknownst to me, were home to carpenter ants. I only noticed this because winged carpenter ants were emerging from pavement ant nest openings. Not only did the pavement ants not mind this, they were stroking the carpenter ants with their antennae, for crying out loud.
In general ants are notorious for defending their nests and territories against invaders, but here they were, together and getting along, the two ant species that can give home owners nightmares. So, in a desperate attempt to put an end to this, I poured boiling hot water along the pathways and into the nest openings. That was over a week ago and I haven't seen an ant there since.
Ants and their relatives cannot tolerate citrus extracts. Oil of citronella, for instance, can make a good barrier when brushed or sprayed around entrances, window frames and anywhere else you may encounter ants in the house. It also must be applied at least once a week to keep the odor strong. Boric acid baits can be effective control measures against pharaoh ants, carpenter ants, pavement ants and Argentine ants, all of which may live in or around buildings. But it is important to note that the feeding requirements may change with the seasons. Argentine ants are more attracted to sugary baits (they tend aphids for their honeydew), while carpenter ants are more interested in protein in the spring and sweet foods in summer and fall.
June 26, 2005
Today I was pleased to see a number of green lacewing adults and eggs in the garden. The adults are very attractive insects and sometimes called 'golden-eyed flies' even though they are not even related to flies. The eggs are easily identified because they are stalked, meaning they are located at the end of a fine, stiff thread about 5-7 mm from the surface and placed most often on the underside of leaves. Lacewing adults feed mostly on pollen, nectar and honeydew, but some are predators of small insects. The real predators are the larvae, also called 'ant lions', which feed ferociously on aphids, caterpillars, mealybugs, and other small insects. To attract lacewings plant a variety of nectar-producing flowers and shrubs throughout you garden.
Adult lacewings are 10-15 mm long, pale green or light brown insects with large golden-green eyes and clear, large, highly veined wings which are held over the body at rest. Larvae are small, light brown alligator-like crawlers with large, curved mouthparts.
Females lay the distinctively stalked eggs singly or in small groups. The eggs are stalked because the larvae are cannibalistic and would eat each other, if it were not for the time it takes to crawl down the stalk and, therefore, have a chance to disperse. The larvae emerge after about a week. All species pupate in silken cocoons, and some fly in May and June, others in late summer.
Throughout most of North America in gardens, meadows and around forest edges. California Green Lacewings are raised indoors by the thousands to be released in greenhouses and vineyards to control mealybugs.
Brown lacewings are relatives of green lacewings and have generally similar habits. They also prey on insects in both their larval and adult stages, but many are specialized, feeding mostly on woolly aphids and mealybugs. Because of their coloring brown lacewings are often overlooked or even mistaken for pests.
Adults are light to dark brown and 10-15 mm long. The antennae and wings are covered with short, dense brown hair. Eggs are attached to plants, not stalked. Larvae are light to dark brown with mouthparts somewhat more pronounced than those of green lacewings. Larvae scavenge in soil debris and on plants and pupate in silken cocoons.
Throughout most of North America in woods, forests, fields, and gardens with dense vegetation.
Lately we have been getting quite a few inquiries about the European chafer. This beetle has been a problem in New Westminster for several years and has also been recorded in Burnaby, Coquitlam, and Vancouver. At this point of the year there are no effective control measures available, since the adults are emerging from the soil to swarm at dusk and mate. Females lay 20-30 eggs in the soil and larvae (grubs) hatch in about 2 weeks. It is when the grubs are young that biological control methods should be employed. To make your grass less attractive to the chafer, make sure that your lawn is healthy by applying sound lawn care practices. Natural lawn care and waterwise gardening can greatly contribute to a healthy yard. If you have proof or suspect that the European chafer has invaded your lawn, please do not remove soil from the area as it may contribute to spreading the grubs. There will be workshops about the European chafer and related lawn care practices in the near future. Check this site for dates.
May 28, 2005
European ground beetle
It's the last Saturday of the month again and I just finished my first round through the garden. While I was looking at the cabbages I noticed a rather large, dark and shiny beetle running away. On closer inspection I identified the sprinter as the European ground beetle, one of our best friends in the garden. There are several species of ground beetles you may encounter in the garden, which range from 3-36 mm in size, are shiny black or iridescent green or purplish with pits or grooves on their wing covers. Ground beetles need to be encouraged to stay by providing permanent ground covers and undisturbed areas in the garden. Overly fastidious gardening will drive them away. Ground beetle adults and larvae prey on caterpillars, snail and slug adults and eggs, plus other soft bodied insects like maggots in the composter. Adults are excellent walkers and can sometimes be seen marching along sidewalks or crossing the patio during the day. Unfortunately, because of this habit they are often stepped upon under the misguided impression that they are somehow "bad". I have had people call me with questions on how to get rid of these beetles. Before you start stomping or spraying anything be sure you know what it is that you are killing. You might be getting rid of the best friends your garden ever had.
Adult European ground beetles are dull black with a glossy head and visible mouthparts. The wing covers are violet or greenish bronze and the pronotum has iridescent violet ridges around front and sides. Each wing cover has 3 rows of pits.
Eggs are laid singly in debris in the spring. Larvae may grow two years before pupating in late summer. Adults emerge in fall, living two years.
Gardens and open woodland throughout some of the United States and most of British Columbia, where they feed on caterpillars like cutworms, and other soft bodied insects.
American hover fly
One of my favorite beneficial insects in the garden is the American hover fly. They are small flies which move up and down plants and hover in flight, hence the name. American hover flies look somewhat like yellow jackets with good reason. The yellow and black stripes on their abdomens are warning colors for birds and other predators, alerting them to the potentially dangerous consequences of eating the flies or mistaking them for wasps. Yellow and black may mean 'I taste awful' and/or 'I can defend myself'. So, wasps, apparently, are unpalatable (I cannot confirm that) and they do sting (that I can confirm), while hover flies pretending to be wasps are tasty morsels (again, unconfirmed) and do not sting (confirmed, they don't possess a stinger). In the animal world imitating something or some one you are not is called mimicry. Hover fly adults feed on nectar and are good pollinators. The larvae prey on aphids, scale insect nymphs and other small, soft-bodied insects. To encourage hover flies to visit and to stay in your garden grow a variety of plants with small, nectar producing flowers like herbs that grow to different heights.
Adult American hover flies are 9-10 mm long and stout. The body is black to metallic green with three yellow crossbands on the abdomen. The wings are clear.
Elongated, single white eggs are laid near or in aphid colonies. Pale greenish-grey, slug-slike larvae feed on the aphids, then drop to the ground to pupate. Adults are active spring to fall.
Gardens, meadows and fields throughout North America.
April 30, 2005
While walking through the garden this morning we noticed several black tips on the ivy and rolled up leaves on the apple tree. On closer inspection we discovered that the ivy tips were covered with black aphids and the rolled up leaves were filled with gray aphids. Both sites were tended by ants. Ants collect the honeydew the aphids produce. Honeydew is the syrup-like anal secretion which develops when the aphids suck sugary plant juices. If you have ever parked on a street lined with trees and wandered what that sticky stuff on your car was, well, now you know. In exchange for the honeydew the ants protect the aphids from potential predators. They will even move the aphids to other plants when the population gets to big and clip off the wings to stop the aphids from leaving. So, if you see ants moving up and down your plants check for aphids.
When not winged most aphids are pear-shaped, anywhere from barely visible to several millimeters long and range in colors from black, green, pink, yellowish-green, reddish brown to dusty gray. They are usually found in crowded colonies on the undersides of leaves and/or in growing tips of most fruit and vegetable crops and on many flowers and ornamentals. Often indications of aphid presence are small, pale fluff-like particles on the plant. These may be the outer skeletons the aphids shed while they are growing.
Aphid eggs overwinter, hatch in early spring into pregnant females which give birth to live female nymphs. These mature into pregnant females within a week which in turn give birth to live female nymphs. There are about seven generations per year. Males appear in the fall and mate with the females which lay overwintering eggs.
Aphids suck plant juices, causing leaf and bud distortion and leaf and blossom drop. Their feeding may cause viral diseases and the sticky honeydew excreted on leaves and fruit supports growth of sooty molds.
Encourage native predators and parasites by companion and interplanting plants with small flowers like herbs. If a treatment is necessary, spray with a garlic, hot pepper and vinegar solution (15 ml garlic oil, 15 ml hot sauce, 15 ml vinegar per liter of water). You might have to spray several times to affect control, but always test the solution on a few leaves first to avoid burning the plant. Squishing the aphids works as well. This has the added advantage in that the smell of the dead may repel other aphids and attract predators. Making a bug juice by collecting aphids and placing them into a blender with water and spraying the solution onto the infested plant has the same effect. Just don't use that blender for anything else, especially not unwashed.
I was looking at the cabbage and noticed some damage on a lower leaf. And sure enough, when I turned it over there was the culprit: the cabbage looper. Cabbage loopers are the caterpillars of a moth and emerge from hemispherical, light green eggs which are laid singly or in small groups on leaves. The looper I found was still very small and had a lot of eating to do before pupating. While cabbage is the preferred food, they can also be found on beet, celery, lettuce, pea, spinach, nasturtium, carnation, potato and tomato. Young loopers typically feed on outer leaves, producing windowpaning patterns on thick-leaved plants like cabbage. Later stages tend to feed more generally and may tunnel into heads. The caterpillars are called loopers or inchworms because when moving they arch they bodies up and forward.
Large gray moths with a silver spot in the middle of each forewing. The caterpillars are pale green, darkening somewhat as they age, with two white lines along their backs, one on each side.
Moths emerge in spring, mate and females lay eggs on leaves. The resulting caterpillars feed on the plants for 3-4 weeks, then pupate on or near the host plant for 1-2 weeks in cocoons attached to stems or leaves. The number of generations per year varies considerably. During the growing season looper generations may overlap and become indistinct.
Check plants and handpick caterpillars several times a week. Companion and interplant herbs to attract predators and parasites. If a treatment is indicated, apply Btk (Bacillus thuringiensis var. kurstak) or spray a garlic, hot pepper, vinegar solution (15 ml garlic oil, 15 ml hot sauce, 15 ml vinegar per liter of water). As always test a leaf first to avoid scalding the plant. Bug juice may also do the trick. Take as many loopers as you can find, place in blender, add water, blend and pour over plants. Chances are that some of the loopers were infected with a virus or fungal disease which may now spread to other loopers. The smell of bug juice also attracts predators to the plants.
One of the earliest visitors to the garden has been a white butterfly which alights on a plant here and there and generally seems to take its time to survey the area. That sounds pretty harmless, but this butterfly can strike fear into the heart of any serious cabbage grower. It's the dreaded imported cabbageworm. The caterpillars or cabbageworms feed on essentially all cabbage family plants including broccoli, Brussels sprouts and many related weeds. Most early feeding occurs on the outer leaves where the caterpillars create large, ragged holes, but the older caterpillars tend to feed more intensively on the newer growth and can tunnel into the heads of plants, soiling the leaves with dark green excrement.
The upper wings of the adults are predominantly white with a dark tip. Males have one black spot on the forewing whereas females have two. The caterpillars are a velvety, medium green with a fine yellow-orange stripe down their backs and move rather sluggishly.
Adults emerge in early spring from overwintering pupae, mate and the females lay yellow, conical eggs with ridges singly or in groups on the underside of leaves. The larvae hatch in 2-3 days, feed for 2-3 weeks, then pupate in the vicinity of the host plant. Adults emerge in 1-2 weeks. There are 3-5 generations per year, overlapping, with larvae present throughout the season.
Use yellow sticky traps to catch and monitor female butterflies. Cover the plants with floating row cover all season. Handpick cabbageworms as much as possible. If the infestation is too large, apply Btk (Bacillus thuringiensis var kurstak) at 1-2 week intervals or spray larvae with a garlic, hot pepper, vinegar solution (15 ml garlic oil, 15 ml hot sauce, 15 ml vinegar per liter of water). Test the spray on a leave first to avoid burning the plant.
March 26, 2005
Mothflies in the Composter
Today I saw mothflies in the composter. They are neither moths nor flies, but are members of the same order as aphids. Mothflies are attracted to decomposing organic matter on which they feed and reproduce. In the compost they are not considered pests, but their numbers can skyrocket. When that happens the best thing to do when opening the lid is to keep your mouth closed. To reduce the numbers, cover the top layer of the compost with baking soda and a newspaper. The baking soda changes the ph level from acidic to alkaline and the newspaper just keeps it in place.
Relatives of the mothflies may be found in your bathroom. They are called drainflies and live in and around the sink overflow opening. This happens when organic matter accumulates in the hole. A good cleaning with an environmentally safe product will take care of that problem. Since I am somewhat domestically challenged, this happens in my bathroom quite often. If I am out of Orange cleaner, I sprinkle some baking soda down the opening and top that off with white vinegar (the cheapest kind). The resulting bubble action usually gets rid of the scum (insect and dirt alike).
A yellowish, shiny and slender insect larva was brought in today and the question was: is it a cutworm? And the answer was: no, its a wireworm. Wireworms are the larvae of click beetles and pests in the soil of vegetable gardens, flower beds and lawns. They live there from 2-7 years and feed on the plant roots, tubers and bulbs. They appear near the surface when the soil is cool in spring and fall, and move deeper as soil warms in summer and again in late fall to overwinter. Mature larvae pupate in the soil in late summer. There is one generation every 2-7 years, but there are usually all stages present. To check, if you have them turn the soil over to a depth of about 30 cm in different areas of your garden. In the spring and early summer you can also stick halved potatoes into the soil and monitor them everyday. To remember where you put them, mark the tops with colored ribbon or twine. Do not stick toothpicks or twiggs into the top, they can be murder on your bare feet. To control wireworm populations delay planting tubers and corms until the soil is very warm, cultivate thoroughly once per week for 4-6 weeks in the fall and apply nematodes. Nematodes are microscopic worm-like organisms which invade the soil-dwelling insect's body and consume it from the inside. When buying nematodes at your local nursery or gardening supply company make sure to mention the pest against which you are applying them; there are several different spieces.
Another gardener arrived shortly after with the actual item: the cutworm and a comparison could be made. While the wireworm was, well, wiry, this particular cutworm was fat and at 3 cm, about twice the length of the wireworm. Cutworms are the larvae (caterpillars) of several species of moths and both are active at night. Female moths lay eggs on grass or soil surface in early May to early June. The eggs hatch in 5-7 days and the larvae feed on plants for 3-5 weeks, then pupate in the soil. Moths emerge late August to early September. Most areas have one generation per year. If a second generation occurs it may damage crops in warm fall weather. During the day caterpillars rest curled beside plant stems below soil surface. Emerging at night, they feed on the plants, cutting them off at soil level - hence the name cutworm. They cause the most damage during May and June, particularly in gardens with newly turned sod. To control cutworms expose them to predators such as ground beetles and birds, parasitic wasps and flies, use cutworm collars on all spring transplants and apply nematodes at the appropriate time.
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