Squash Bugs & Squash Vine Borers
Growing squash in your home vegetable garden can reward you with heavy yields for little work. However, avoiding insect infestation, specifically squash bugs and squash vine borers, is critical to success. We have battled these pesky creatures in our garden over the years. Luckily there are several rather simple preventative steps that will help to ensure success without the use of harsh insecticides.
Squash bugs are relatives to the stink bug with a life cycle of about eight weeks. The adult lays clusters of small reddish eggs on the bottom side of the squash leaf, when they hatch the nymphs will go through five stages of development called instars before maturity.
This allows one or two generations per year depending on your particular climate. Bugs will overwinter in garden debris or nearby weedy areas, sheds, wood piles, etc. Squash bugs damage the crop by injecting toxins and sucking the juice out of the leaves, leaving brown patches or entirely dead leaves or plants.
Squash Vine Borers
Squash vine borers are larvae of a type of moth. The moth, which with its clear wings, dark body and orange legs and antennae resembles a wasp, lays eggs singly at the bases of leaf stems.
A week later when the egg hatches, the caterpillars reach a length of 1 inch and have a brown head and a cream colored body. It damages the plant by chewing its way into the leaf stalk and on through the body of the plant. When it’s ready to pupate, the caterpillar drops to the ground and digs in to form its cocoon. It over winters one to two inches below the soil surface. It emerges as an adult the following spring and spends the early to mid summer reproducing.
Insecticides are a difficult way to manage squash vine borers and squash bugs. The same chemicals that kill these bugs will also kill bees, and that is a very bad thing. Squash are not self fertile, they bear male and female flowers separately, and need the bees to pollinate their flowers. Physical controls for the nuisance insects are a much better proposition.
Here are some tips to help you successfully grow squash:
- Because the bugs overwinter in the soil where the plants grew, never grow squash in the same part of the garden in successive years.
- Avoid deep layers of mulch, use a hoe to keep the soil loose and weed free to minimize hiding places for the bugs.
- Start seeds indoors to give them a headstart on the bugs’ life cycle. This may allow them to begin producing before the bugs have emerged. Do this for a late crop as well to get a fall crop that will miss the bugs after they have gone back into the ground.
- Opt for bug resistant squash varieties, such as Butternut, Early Summer Crookneck, Improved Green Hubbard, and Royal Acorn.
- Plant marigolds and nasturtiums among squash plants as a deterrent.
- Use row covers over squash plants until they begin to flower (remove them to allow the bees access or you will not have squash).
- Look for “frass” (caterpillar excrement) at the base of stems or along vines, and if any is found, either slit the stem open along its axis or use a needle or wire to kill the caterpillar inside.
- Leave scrap boards in the rows adjacent to squash plants to give them a hiding place where you can easily find them and remove them by hand.
- Inspect the undersides of leaves for egg clusters and remove them as they are found. Immediately remove plants that have succumbed to insect damage.
- Remove squash vines and debris as soon as production is finished for the season and either compost or burn them.
By following even some of the above practices you will greatly increase your chances of a successful squash harvest. As with many things, when it comes to control of squash vine borers and squash bugs, knowledge is power.