Saturday, December 02, 2006

Pest Control in Your Garden!


Pest Control

In our bid to control or eliminate those creatures and disease, which damage or ruin our crops, we must look to enhance the environment to attract natural predators to assist us in our task. It is of course a long-term approach but one that can only benefit both the environment and us. Organic gardening relies on several overlapping strategies rather than the power of a single highly toxic chemical to kill the pests. We must encourage the pest's natural enemies such as ladybirds, lacewings, spiders and tiny parasitic wasps. Many beneficial insects that feed on garden pests need nectar and pollen for food during part of their lifecycle. Growing a year-round supply of suitable flowers close by will maintain the insect populations throughout the year. Keep the insect eating birds visiting your garden by providing them with safe nesting sites, offer safe hiding places for frogs and hedgehogs.

I have included some of the pests we are likely to encounter when growing vegetables, but by using good growing practises, good husbandry, crop rotation, and watchfulness, we can overcome most if not all.

Aphids (Greenfly, Black fly, etc)

These tiny creatures are the most abundant pests in the garden, and most plants, including vegetables, are liable to attack by one or more species of aphids. Aphid's feed by sucking the sap from a plant and by congregating in there hundreds and in some instances thousands. On tender young growth, they can quickly suck the life out of the plant or at least stunt the growth and disfigure it. To add to this they can also transmit virus disease, which can often wipe out an entire crop.

Keep a close watch for these little fellows; a few individuals can quickly multiply into a swarm especially when the weather is warm. The Black Bean Aphid is found on beans, beetroot and spinach. You will have to look more closely for the Carrot Aphid because its colour is almost identical to the leaves of the carrot. The Cabbage Aphid is greyish-white and can be found tightly packed in colonies on the leaves and stems not only of cabbage but Brussels sprouts and cauliflower. Once these take hold they invade the inner leaves of the heart making the plant inedible.


Many people are discovering that the control of aphids and other pests is within the general management of the land, enrichment of the soil and good husbandry, clearing away debris and waste after harvesting crops, weed control, all assist in controlling many pests. However, a garlic spray or a weak application of insecticidel soap should help to eliminate these sapsuckers.

Carrot Fly (Psila rosea)

It might be a good time to mention this beastie the scourge of the veggie plot, who sets the carrot grower's teeth on edge. It is a very small black fly, which is believed to seek out its prey (the carrot) by the smell. The eggs are laid in the soil adjacent to the carrots where the grubs over-winter in the ground gorging itself on our carrots! However other plants may also be chosen as laying sites, Parsley, Cow Parsley, Celery and Parsnips are other favourites. The spring generation who are ready to procreate hatch ready to begin to lay their eggs in June and July.

The gardener is generally unaware that his carrots have been attacked until they are lifted. However in severe infestations the first sign is that the carrot leaves look yellowish-orange or rusty. As soon as the culprits are discovered the crop should be lifted and destroyed. Some carrots may have escaped this grubs greedy jaws or at least part of them might. For those who do not appear to have been affected the simple test of dropping them into a bucket of water can be tried. If the carrots float then they most certainly have been attacked, even so part of them still might be rescued. Many gardeners choose to grow a variety that is resistant to carrot fly but it obviously restricts the wonderful choice and variety that we have available to day which is a great shame. To prevent carrot fly attacks it is important to put up some sort of defence and there are several options.

Companion planting - Many people are convinced that a screen of strong smelling plants situated close by the carrots will deter the fly. Onions and Garlic are said to have a great repellent effect. However these do have limitations, even if they are of use, they are for only a limited time span of two months because they are lifted well before the fly is at it's most copious time in early autumn.

Barriers - This is the method that I would personally choose to use.

A barrier of fine horticulture fleece, available from most good garden centres and DIY stores is supported by thick strong wire hoops or a frame made from stout canes, while the edges of the fleece on the ground, is weighted down with half bricks. The fleece allows light and moisture to penetrate through so will not restrict the growth of the vegetables. Of course it must be taken down temporarily while weeding takes place. Fleece also allows early plantings as it does give a little shelter and this will assist with the 'Timing' option


The caterpillars of the Large Cabbage White Butterfly (Pieris brassicae) have green, black and yellow markings.

The velvety green caterpillars if the Small White Cabbage Butterfly is a common pest of cabbage, Swede, and kale, and can be found throughout the summer devouring the leaves with devastating speed, at the end nothing but the leaf skeleton and the main stalk remains.

The adult all white butterfly emerges from the pupa (chrysalis) in April and May, mates after which the female lays 20 to 100 yellow eggs on the underside of the plant leaves. It takes about 14 days for the larvae (caterpillars) to hatch out. They have well developed mandibles, which they use with devastating effect on the crops. This generation pupates in June, then emerges in July to repeat the cycle, pupates then over winters for the next year.


Protect the plants by putting up a barrier of fine netting or horticultural fleece; this will prevent the butterfly from laying her eggs on the plants. Alternatively, Apantales glomeratus, a small parasitic wasp, is a biological control, which lays its eggs in the caterpillar. You can also try to pick off as many caterpillars as possible. Now this might sound a tall story but I swear it is true. After picking off dozens of the Large White Butterfly caterpillars from the cabbage patch, I took them through to the next garden and tossed them into the pond, curious as to whether the fish would eat them, although I had my doubts because of the caterpillar's colouration (black and yellow). Well the fish didn't attempt to eat them but to my amazement, out of the pond climbed these creatures; down the path they walked, out to the vegetable garden towards the cabbage bed! Of course they were not allowed that far but it makes you think!

Flea Beetle

The name flea beetle is a generic name applied to a collection of bugs, which can do sever damage to our crops. Those crops, which are particularly attacked, are beans, beets, eggplant, peas, potatoes, pumpkins, spinach, sweet potatoes and watermelons.

1. To help control these pests make sure that weeds are kept clear of the vegetables because this will help to deprive the larvae of food.

2. Remove old crop debris as this gives winter protective cover for the beetles.

3. Crop rotation is particularly good practise to reduce food for the larvae.

4. Growing garlic close by is said to discourage the bugs from hanging around

Slugs and Snails are an absolute menace in the garden. Not only do they gorge themselves on our plants, they leave behind the most disgusting, slimy trail, which, once they have slithered their way over the crop, greatly reduces our enthusiasm to eat and enjoy them ourselves.

Slug pellets do work but they are life threatening to other creatures in the garden, other creatures that we would like to encourage because they work with us, helping to eliminate other pests that would otherwise feast on our crops. Beer traps work well, just put some beer into a shallow container that has steep sides, the slugs love the stuff and when they have drunk their fill they simply drown. Seeing their stranded brethren does not seem to deter their fellow snails from slithering into the same fate. Milk or grape juice works just as well! Another good trap is to place a half of either grapefruit or melon skin with the flesh removed of course. Place them upside down on the ground; here the slugs gather over night; these can be collected the next morning and disposed of.

Onion Fly

These are the adult flies, whose eggs produce the damaging maggots that attack onions. The eggs are laid at the base of the plants, when they hatch the maggots feed within the onion bulbs. Because garlic appears to be immune to this pest, garlic is used as an organic method to deter the fly from visiting the onion plants. Make up a spray solution with half a cup of crushed garlic cloves to a pint of water; allow this to stand for two or three days, then spray the onion plants daily. This can be done on a daily basis as a cure or simply as a precautionary procedure. Prevention is always better than cure so it is very important that after the onions have been harvested none should be allowed to remain on or in the ground as this is a source of food for the maggots so that they are able to over-winter readiness for the coming year.

Wireworm (Agriotes lineatus) this creature, which grows to about 25mm long, spends four years living in the ground. During the summer they pupate, this stage lasts for three weeks, to emerge as adult Click beetles. They feed on roots particularly potatoes and other root crops, making tunnels about 3mm in diameter. They are usually widespread in grassland so will be frequently found when it is brought into cultivation. It is believed that after five years of cultivation their numbers drop considerably.


1. Lift main-crop potatoes before September, as most of the damage is done at this time.

2. Crush any that are found when digging.

3. I have heard that a trap made of squares of potatoes attached to skewers, buried in the ground is a good way of catching them, these can be pulled up and the infested potato destroyed. I must admit that I have not used this method, but it is one I might try.

4. Keep down weeds, as this is the sort of territory that the beetle likes to lay its eggs.

Terry Blackburn. Internet Marketing Consultant, living in South Shields in the North-East of England. Author and Producer of blog Author of "Your Perfect Lawn," a 90 Page eBook devoted to Lawn Preparation, Lawn Care and Maintenance. Find it at

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