Squash Vine Borer is a common pest of cucurbit crops, such as squash, pumpkin, zucchini, and other similar plants. It is a type of moth that lays its eggs on the stems of these plants, and when the eggs hatch, the larvae tunnel into the stem and feed on the plant’s tissue. This feeding results in wilting of the plant, discoloration of the stem, and ultimately, the death of the plant. The larvae also produce frass (insect excrement) near the base of the stem, which looks like sawdust or small pellets.
Squash Vine Borer infestations can cause significant damage to cucurbit crops in a garden, leading to decreased yields and reduced plant health. Therefore, it is important to be aware of the symptoms of infestation, regularly inspect your plants, and take appropriate action if you see any signs of the pest.
Symptoms
It is important to inspect your cucurbit plants regularly for these symptoms and take action if you see any signs of infestation. Early detection and treatment can help prevent significant damage to your plants.
- Wilting of leaves, usually starting with one or two leaves and spreading to the entire plant. This wilting occurs suddenly and is often mistaken for a lack of water or disease.
- Yellowing of leaves, starting at the tips and working downwards, which is a sign of a dying plant.
- Soft, mushy stems near the soil line and holes or cracks in the stem that ooze sap, which is a clear sign of a borer infestation.
- Presence of frass (insect excrement) near the base of the stem that looks like sawdust or small pellets.
- Decreased production of fruit or complete cessation of fruit production, as the infestation weakens the plant’s ability to produce fruit.
What is a Squash Vine Borer
It is important to be familiar with the appearance of the Squash Vine Borer so that you can identify it in your garden and take appropriate action to prevent an infestation. Familiarizing yourself with the appearance of both the adult moth and the larvae can help you to quickly and accurately identify the pest and take appropriate action to control it.
Adult Moth
- The adult moth has a wingspan of about 1.5 inches.
- The front wings are iridescent blue-black with metallic green markings and are narrow, elongated, and slightly curved at the tips.
- The hind wings are orange-red with metallic silver markings and are rounded and slightly frayed at the edges.
- The body is plump and orange-red in color, with black markings along the sides.
- The head is black and has a pair of large compound eyes and long antennae.
- The legs are short and orange-red in color.
Larva
- The larvae are about 1 inch long and plump, with a fleshy body that tapers at both ends.
- They are white in color, with a brown head and several small legs near their head.
- The larvae have a smooth and slightly shiny body, with no visible legs or other appendages.
- They have a pair of small black eyes and a fleshy head, which is brown in color.
- The larvae lack a distinct segmented body and have a slightly curved body shape.
Treating a Squash Vine Borer Infestation
It may be necessary to use multiple methods to effectively control a Squash Vine Borer infestation in a garden. For example, using a combination of physical and cultural control methods, such as stem wrapping and rotating crops, can help to reduce the number of adult moths that are present in the garden and prevent infestations.
Physical Control Methods
- Caging: Covering the plants with cages or screens to prevent adult moths from laying eggs on the stems. This method is best used in conjunction with other methods, such as stem wrapping or pruning, as it will not prevent adult moths from laying eggs on the leaves or other exposed parts of the plant. The cage should be tall enough to cover the entire plant and have a tight-fitting lid to prevent moths from entering.
- Stem Wrapping: Wrapping the stems of the plants with aluminum foil or a sticky material, such as Tanglefoot, to prevent adult moths from laying eggs on the stems. This method works by creating a barrier that moths cannot penetrate, preventing them from laying eggs on the stems. The wrapping should be done tightly and securely, covering the entire stem from the soil line to the first set of leaves.
- Pruning: Pruning away infested sections of the stem and disposing of them to prevent the larvae from spreading. This method works by removing the larvae from the plant and preventing them from spreading to other parts of the plant. The pruning should be done as soon as the infestation is detected and the infested section of the stem should be disposed of to prevent the larvae from re-infesting the plant.
Cultural Control Methods
- Rotating Crops: Planting cucurbit crops in a different area of the garden each year to reduce the buildup of Squash Vine Borer populations in the soil. This method works by reducing the number of adult moths that are present in the garden and reducing the likelihood of an infestation. The rotation should be done annually and the area where the cucurbit crops were previously planted should not be used for cucurbit crops for at least three years.
- Planting Resistant Varieties: Planting cucurbit varieties that are resistant to Squash Vine Borer infestations can help to reduce the likelihood of an infestation. This method works by selecting varieties that have thicker stems or a more compact growth habit that makes it harder for the larvae to penetrate the stem. The choice of variety will depend on the climate and growing conditions in your area.
Chemical Control Methods
- Insecticide Sprays: Applying insecticide sprays to the stems and leaves of the plants to kill adult moths and larvae. This method works by applying a chemical that is toxic to the Squash Vine Borer to the plant, killing adult moths and larvae that come into contact with it. The choice of insecticide will depend on the severity of the infestation, the size of the garden, and the resources available to the gardener. The insecticide should be applied according to the manufacturer’s instructions and repeated as necessary to control the infestation.
- Soil Drench: Applying a systemic insecticide to the soil around the base of the plant to control the larvae as they tunnel into the stem. This method works by applying a chemical that is taken up by the roots of the plant and distributed throughout the stem, killing the larvae as they feed on the stem. The choice of insecticide will depend on the severity of the infestation, the size of the garden, and the resources available to the gardener. The insecticide should be applied according to the manufacturer’s instructions and repeated as necessary to control the infestation.
Biological Control Methods
- Attracting Beneficial Insects: Attracting beneficial insects, such as ladybugs and lacewings, to the garden by planting flowers or using insectary plants can help to control Squash Vine Borer populations. This method works by providing a food source for these insects, encouraging them to establish a population in the garden and feed on the eggs and larvae of the Squash Vine Borer. Flowers that are attractive to beneficial insects include dill, fennel, and coriander, while insectary plants, such as sweet alyssum, can also be used.
- Using Parasitic Wasps: Releasing parasitic wasps, such as Cotesia congregata, into the garden to control Squash Vine Borer populations. This method works by introducing a natural predator of the Squash Vine Borer into the garden, which lays its eggs in the larvae of the Squash Vine Borer, killing the larvae and reducing the number of adult moths that are present in the garden. The parasitic wasps can be purchased from a garden supply store or online and should be released according to the manufacturer’s instructions.