The Squash Vine Borer is your Enemy and Here’s How to Defeat Them.

You’ve started your summer squash and zucchini. The plants look great! A couple of weeks later, the plants start to wilt and some die. What did I do wrong? After careful observation, you notice there is something that looks like wet sawdust at the base of the plant. Plus, you see small holes in the bottom stem. What is going on?

SVBwilt  SVBdamage

Your enemy is the Squash Vine Borer!! (SVB)

svb

The female Squash Vine Borer moth (Melitta curcurbitae) lay brown eggs especially on the stems, just above the soil line.

squash-vine-borers-3-sm  SVB1SVBmating   SVBeggs2

Eggs hatch in 10 days. Once the eggs hatch, they immediately enter the stem, leaving a small hole at the place of entry surrounded by frass (moist sawdust like debris). The larvae (white caterpillars with brown heads) bore into the stem and remain until maturity before pupation (the transformation of the larvae to a pupa(in a cocoon)). They will now stay in the soil (usually 1″-2″) and over winter .

squash-vine-borers-4    SVBmoth_pupae

Squash Vine Borer moths emerge from the ground from early spring through mid-summer. The moth looks like a wasp and is a half inch long. The wings are clear and look like a windowpane. Unlike other moths, this one flies during the day and makes a buzzing sound.

Now that you have identified the enemy, what are your weapons of warfare?

  • A preemptive strategy would be to use a floating row cover (sheer, light weight fabric that is placed over a crop to protect from insects). It is secured in place to prevent insects from damaging the crop. The row cover is put on at the time of planting until the plants begin to flower. Squash crops require insect pollination.
  • Monitor by using a yellow colored bucket trap with water, placed near the newly planted squash plants. The yellow color attracts the moths.  Traps must be checked daily. Once you’ve found moths in the traps, start looking for stem damage. This indicates the female moth is out laying eggs.
    • SVBtrap
  • Create a barrier on the lower stem by using materials such as aluminum foil. Wrap the foil around the lower stem to confuse and prevent the moth from  laying eggs.
  • Plant a trap crop of early planted Hubbard squash three (3) weeks prior to planting your preferred squash crop.
  • Use succession planting (weather permitting). Have fresh transplants ready to go. A late crop planted after SVB pressure may offer a harvest. Do not plant your late crop where there has been previous pressure from the SVB. Rotate your planting to an unaffected area.
  • SVB resistant varieties of squash, such as Waltham Butternut, offer a solid stemmed variety to thwart the penetration of the larvae. Cucurbita moschata are their least favorite, as they are solid stemmed. Cucurbita pepo are their most favorite, as they are hollow stemmed. Seed catalogs will list this information for each squash seed offered.
  • When a squash plant has been attacked by the squash vine borer, find the borer by looking for the frass or small holes with frass. Carefully slit open the stem and remove the caterpillar. Cover the wound with fresh soil or compost to encourage the re-rooting of the plant.
  • Remove and destroy any plants that are severely wilted or dead immediately. Do not compost these plants!!
  • Sanitation is key! Immediately remove your squash vines after harvest. Do not compost!! Burn the vines or bag the vines and remove them from your property. The soil must be exposed to reveal the cocoons.
  • Till or fluff the soil up to 2″ to expose SVB cocoons. Songbirds and poultry delight in eating the pupae (cocoons).
  • Always rotate your squash crop to another space each year.

My strategy this year includes the Blue Hubbard trap crop and yellow trap buckets. Plus, I will preemptively spray the ground stems with a mixture of vegetable oil and Dipel (Bacillus thuringiensis). I’ll keep you updated throughout the summer.

Papa

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12 thoughts on “The Squash Vine Borer is your Enemy and Here’s How to Defeat Them.

  1. Great Article and Awesome Photos! Thanks!

    One additional strategy that I’ve had a lot of success with for my winter squash and pumpkins is to cut the bottom off a 5 gal bucket or large plastic plant pot. When I plant the seed, or if started, when I plant the plant, I set the open ended bucket or pot over the small plant/seed, and pile mulch around the bucket. I cover it with old sheer curtain or row cover cloth and tie it on to the open top with string or binder twine.
    The plant can grow with out animals, chickens or bugs bothering it and it can get plenty of water and sunshine this way.
    When its big enough and trying to grow out of the top, before it flowers, I take the cloth off the top, but leave the bucket there. The plant will grow out the top just fine. Because the squash vine borer moth doesn’t like to go down into a container or a hole, it wants to be at the surface on level ground it will leave the base of the plant in the pail alone. This is behavior is the key to this method. In many years I’ve never had a squash or pumpkin die from squash vine borer using this method. On occasion, a single vine that branches off above the pail may be affected, but the vast majority are fine.
    This method works well for summer squash and zucchini too, but since some varieties branch off lower to the ground, a shorter more flexible plastic pot may be needed. And sometimes I need to cut a slit up the side as the plant gets larger if the pot isn’t wide enough. Hope this helps too.

    Liked by 1 person

    1. Hi Jamie,
      Thank you so much for your comments and observations. It is amazing how many ideas and solutions are coming to the light. With your permission I may add some of your ideas.
      Thanks,
      Papa

      Like

  2. It’s been years since we planted summer squash, but we had great success treating/saving plants: carefully slice affected stems horizontally, scrape out eggs etc. mix together flour and ALOT of cayenne pepper and place in scraped out stem. Cover with dirt and most times plant will recover and produce normal fruit.

    Liked by 2 people

  3. We had fewer attacks last year when we planted marigolds and top sets of walking onions around the squash plants near the base. Strong smells of these companions seemed to confuse the squash bugs.

    Liked by 1 person

    1. Hi Elaine,
      Thank you for sharing about companion planting to confuse squash bugs. Aromatic herbs are very effective in disrupting the senses of the squash bugs, squash vine borer and cucumber beetles.
      Thanks,
      Papa

      Like

  4. Thank you for this! I have had a bad couple of years due to these monsters. I have looked up ways to get rid of them but this is the first time I have seen the pupae. I have found a lot of those but didn’t realize what it was. I will do more digging in search of them.

    Liked by 1 person

    1. Welcome to Papa’s Gardens.
      So glad this article will offer help during this upcoming growing season. Let me know of your successes.
      I usually plant in the fall to avoid the creatures and have had great success.
      Papa

      Like

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