There are a number of ways by which you can control pests from invading your roses or other plants. In case you prefer to employ biological methods to deal with the insects, first you need to have a good understanding of the insects that can be used to counter the harmful pests as well as the latter. When you have a clear idea of the life cycles of both, you will be able to find different means you can adopt to disrupt the life cycles of the damaging insects and, thereby, also put off these insects from propagating regularly to infest your garden.
Perhaps, aphids are among the most common pests that trouble roses. Aphids are small creatures having a soft lime green body. They, however, have sharp mouthparts that are used to pierce the soft, new developing plant tissues and enable these pests to suck out the juice from the plants that they invade. If your rose is heavily infested by aphids, its young, tender leaves will first begin to curl and eventually become desiccated. You will always find aphids on the underside of the leaves, close to the shoot ends. While the aphids feed on the tender tissues, they expel a sticky substance that attracts ants. This sticky substance is known as “honeydew” and many species of ants feed on it. In fact, it has been found that some ants feeding on “honeydew” also protect the colonies formed by aphids from other bugs. If the amount of “honeydew” is significant, it will turn blackish, forming molds on the surface of the stems. If it remains on the stem for some time, fungus starts growing on “honeydew”.
It has been found that aphids are among the most productive insects that exist today – they reproduce profusely. Aphids survive throughout the winter on the stems in the form of minute black-colored eggs, which are generally found close to a bud. Tiny nymphs hatch out of these eggs in spring and they rapidly develop to their full size. The aphids that appear on the stems first are known as “stem mothers”. Aphids possess the amazing ability to hatch their off-springs without being fertilized by a male. This helps aphids to reproduce several new generations for a brief period.
Subsequent to the “stem mothers”, a new generation with wings emerges. The winged aphids are known as migrants, as they take to the air to reach different parts of the same plant or even other plants that host them during the summer. To some extent, this is some sort of an annual affair in the life cycle of aphids. When the days become shorter, aphids give birth to a new generation, which not only has wings but also comprises males and females. The female aphids of this generation are known as fall migrants, which fly only to plants on which they began in the previous spring. Subsequently, these female aphids or “fall migrants” give birth to another generation comprising wingless aphids. These wingless female aphids can only produce eggs when they are fertilized by male aphids. The wingless female aphids lay their eggs close to the buds as well as the cracks in the plant. The eggs hatch out in spring completing the entire reproduction cycle of aphids.
Theoretically speaking, a single aphid possesses the ability to produce several million aphids by the time its life cycle is completed. In such a situation, there would actually be a swarm of aphids all around us. However, this does not happen as there are several predators, including bugs and birds, which relish on aphids. If you are watchful, you can see small lonely spiders in your garden trapping and consuming aphids in spring. Some time later, you can also notice other predators like the small gall midge as well as the syrphid fly’s larvae feeding on aphids. The most effective opponent of aphids – lady bugs – appears on the scene as spring advances. In fact, the adult lady bugs invade aphid colonies just when they begin to proliferate rapidly and lay their eggs in these colonies. After a couple of weeks, very small, opaque and famished larvae emerge from these eggs and they start feeding merrily on aphids. These larvae have quite large snouts, which they use to hold the aphids and suck the aphid’s insides out.
These ladybug larvae grow almost 20 times bigger compared to their initial size and start eliminating the aphid colonies vigorously. The growing lady bugs go from one aphid colony to another till they grow to their utmost size. Subsequently, a hard shell develops around these mature lady bugs and they form pupae. It takes another two weeks’ time for the winged lady bugs, which we all are familiar with, to emerge from the pupae. At this stage, they resemble the rounded beetles and usually come in yellow or red outer shells and have many dark specks on their wings. Even the winged lady bugs consume aphids, but they are fewer. It is actually the young lady bugs that are menacing for aphids.
In fact, it is wise for you to do absolutely nothing when you first notice aphids on your roses. It would be a blunder using a spray at this stage – even if you use a soap water solution or any other non-toxic substance. This is because the eggs or even larvae of ladybugs as well as those of other aphid predators will also be killed when you apply these substances. Therefore, it is advisable that you just keep watching the aphids developing in your garden, even if it means grinding your teeth in frustration. If you just wait for some time, possibly another two weeks or so, you will be seeing the first signs of the small ladybug larvae already at work. Soon you will find that the aphid colonies have been reduced to nothing but vacant white husks.
When the ladybugs have already become established in your garden, they will work to keep the level of the aphid infestation at the lowest levels. Provided you are growing your roses in a thin sandy soil, you may possibly see that certain ants in your garden are guarding the aphid colonies against their predators. You can solve this issue by spreading a slight stratum of mulch in your garden. It has been found that ants have a preference for an arid, well-drained soil and when you use mulch, it makes the soil moist, discouraging ants from building their own colonies in your garden.
On the other hand, if you are growing your roses in a greenhouse – a place where you don’t have ladybugs, you still have several alternatives to keep aphids in check. You can purchase aphid predators from various companies specializing in the manufacture of biological controls. Alternatively, you can also water the entire plants using a garden hose on a regular basis. The strong stream of water will force the aphids to drop on the ground. Therefore, it is an effective method that does not harm your plants. Using insecticidal soaps may also prove to be very effective in controlling aphids. In fact, the last method can be very effectual for greenhouses where you do not have the usual insect-plant relationships.
These are very small insects usually having an orange or black color. They are so tiny that you require a hand-held lens to see them properly. Usually, they become visible only after the formation of the gall sometime around their larval stage. The gall wasps are damaging for plants, including roses, as they disrupt the supply of nutrients as well as water to the stem part of the area where they form. At times, you may even notice a considerable number of these galls. In case you do not adopt any method to control the gall wasps, they may develop to such high levels that can affect the vitality of the roses seriously.
The adult wasps generally lay eggs during spring. The eggs are put down on the stem of the rose plant. The larvae emerge after about three days of hatching. These larvae start feeding on the plants, which respond by turning out tissue masses around them. The larvae lie dormant throughout the winter inside the galls, which form their protective shields, and pupate in spring. When the host plants develop to an appropriate size, the adult wasps feeding on the plants make holes through the galls’ sides. Subsequently, they emerge from the other side and lay eggs to give birth to a new generation of the pest.
Although gall wasps occur often in gardens, they rarely cause any severe problems for roses. You can control gall wasps by removing them immediately when you find them. Cutting the wasp into halves using a sharp knife will make the larvae developing inside visible. After you have removed the gall, bury it or, even better, burn it to make sure that another generation of the pest does not arrive at trouble your roses. If you are watchful enough, you can also find gall on many other plants, especially oak trees and goldenrod.
Leafhoppers are tiny, but extremely active insects whose color varies from light green to greenish white. These creatures have sucking mouthparts and survive on foliage. Usually, leafhoppers are present on the underside of leaves. When you examine these creatures through a hand-held lens, you will notice that their head is relatively large, while their body is rather triangular. They have wings that emerge from the high ridge the length of their rear. While leaf-hoppers seldom pose a serious problem for your roses, they do have the ability to diminish the vitality of the plants they infest badly.
The adult leafhoppers, as well as their eggs, lay dormant throughout the winter, surviving the cold temperatures. In the beginning of spring, adult leafhoppers become very active and sometimes even mate before the new leaves appear in spring. They lay their eggs into the leaves’ midrib and by the time the leaves are fully grown, the new generation of leaf-hoppers is ready to arrive. Living up to their name, young leaf-hoppers keep hopping from one leaf to another. If you shake up a plant that is heavily infested with leaf-hoppers, you will soon let loose a large number of these creatures into the air. However, they are not good flyers and will again settle on the leaves or fall on the ground. Every year, many new generations of leaf-hoppers come into existence and while each leaf-hopper grows larger, it drops its skin during the course of molting. As the tiny pieces of their skin stick to the leaves’ underside, you can easily detect the presence of these creatures in your garden.
The population of leaf-hoppers varies every year depending on several aspects. The best way to keep leaf-hoppers at bay is to ensure that your plants continue to grow actively. These creatures seldom have any effect on plants that are well-fed and watered properly.
There are several types of mites, which have a close relationship with spiders. In fact, your roses can be infested by various different types of mites. The European red mite is most widespread in the gardens in the northern hemisphere. On the other hand, the two-spotted mite, as well as the spider mite, is common in greenhouses. You can tell that mites have infested your roses if you notice that their leaves are turning yellowish and formation of delicate web-like structures on the lower side of the leaves. Mites are very tiny and you can only see them with the help of the hand lens. Basically, mites are sucking pests that survive in the plant tissues and eventually destroy the leaves by sucking out their internal tissues.
Mites overwinter on the branches in the form of tiny red eggs. These eggs are usually found close to the bud scars or in the fissure of the branches. The eggs hatch around the time when the blossoms of apple trees are just opening. The new generation of mites starts feeding on the leaves. When the conditions are favorable, the mites start multiplying at a rapid pace. The life span of mites is extremely short, usually spanning for just four days. This is one reason why numerous generations of mites appear every year. However, the number of generation of mites is relatively fewer in the northern hemisphere, as the cooler growing season there is shorter in these places.
If you spot mites on your roses, you should be sure that the plants are not being watered properly or they are suffering from an insufficiency of water. It has been found that vigorously growing roses that have been receiving sufficient water are seldom invaded by mites. In fact, providing your roses with proper mulching will help to ensure that the soil remains wet always and this helps to keep mites away. In case the weather in your area is extremely arid, it is important that you soak your roses thoroughly from time to time. Whenever you see mites on your plants, wash the foliage with water. It is worth mentioning here that once the mites have been dislodged from the leaves, they are unable to infest the plant again – as their lifespan is too short for this.
There are numerous insects that survive on mites. For instance, particular thrips species are said to have an insatiable craving for mites. These thrips species consume the adult mites as well as their eggs. Some predator mites also eat them. In addition, ladybugs, as well as other related bugs, also have a preference for mites.
There are many different sawfly species that survive on roses. Most of the damages done to roses by sawflies are when they are in their larval or caterpillar stage. Sawflies are quite small, measuring just about half an inch (1.3 cm) in length and rather distended in the front. When active, sawflies have a typical habit of clinging onto the leaves using their front feet, while the remaining body is curled upwards into the air. While the sawflies are resting, they keep their body curled on the lower side of the leaves. There are a number of sawfly species that actually roll or turn over the leaves as they feed on them. There are others that eat the entire leaf, just leaving the main veins. The number of sawflies differs every year. When the infestation of sawflies is very heavy they have the ability to harm the rose foliage badly. In fact, sawflies are amongst the most exasperating pests in your garden.
As with many other pests, even the adult sawflies lay their eggs on the leaves. Upon hatching, these eggs produce very small larvae that start feeding on the leaves immediately. After becoming full-grown, the sawflies drop to the ground. Once on the ground, they begin to weave cocoons that surround them. These pests continue to be in the leaf garbage until the onset of spring. After a while, they emerge from the cocoons with wings and start laying eggs when they mature, thereby, commencing a new cycle.
The population of sawflies differs so much from one year to another that in some years gardeners do not face any problem from these pests. In other years, when their population is very high, sawflies may eat up all the leaves of a plant, completely stripping a rose bush. As soon as you notice sawflies on your rose, you should hand pick them carefully to make the plant free of these pests. In fact, the number of sawflies is picked by you, the lesser will be their reproduction. Here is a simple, but very effective way to get rid of sawflies. Kick or beat the affected rose bushes lightly using a padded stick and you will see hordes of sawfly caterpillars dropping to the ground. When they are not in their habitat anymore, these pests become preys for the insects and birds that move on the ground. If the sawfly infestation on the plants is heavy, you can treat them by using a number of substances, including insecticidal soap, pyrethrins, and rotenone.
Nevertheless, these substances should only be used when other methods fail. They are certainly the last resort of removing sawflies, as they also disturb the populations of other insects, some of which may be beneficial for your rose. If the infestation of sawflies in your garden is really heavy, you should first re-work the soil around the plants and put an additional layer of mulch, as this will go a long way in destroying the cocoons that were lying dormant on the ground throughout the winter. The mulch will bury these cocoons under the damp soil, thereby preventing the new generation of sawflies from emerging. At the same time, it will be wise to encourage birds to visit your garden, as they are among the main predators of these pests.
These bugs are also called froghoppers. Usually, spittle bugs become visible only when they create a layer of white foam that surrounds as well as protect them. This white foam bears the resemblance to spit. These bugs with sucking mouths inhabit the stems of various plants and extract their sap. Roses are a major victim of spittle bugs.
Spittle bugs start their life in the form of eggs that produce tiny green nymphs after hatching. These little nymphs molt throughout the year and gradually become larger while doing so. Sooner or later they mate and produce eggs during the fall, thereby giving rise to a new generation in the subsequent year.
Spittle bugs are noticeable, but they do not harm the roses much. However, from time to time, these bugs may appear in the larger number of your rose bushes. However, you can get rid of them quite easily by picking them manually or by using a garden hose to spray them off.
Apart from the pests discussed above, there are several others that invade roses. Such insects include the chafed beetles, Japanese beetles, and earwigs. It is advisable that you visit your rose garden regularly to inspect the plant as well as to learn how to ascertain that these damaging pests are present in your garden. If you detect infestation of these pests quite early, generally hand picking them will be enough to take care of the problem. However, the earwig is a nocturnal pest and difficult to trap during the day. Hence, it is advisable that you make traps using corrugated cardboard strips to catch them. Usually, the earwigs creep into corrugated strips at the crack of dawn. Once you have trapped them using this method, get rid of them from your garden.