July 30, 2011

1 - Late planted squash is not always safe from squash bugs.

Yard and Garden - July 30, 2011


This year I dutifully and hopefully waited to plant summer squash to avoid the squash bugs. I got them anyway! It occurred to me the native squash about 40 feet from my garden, after all is a squash, and might it be a host of the 'bug'? Sure enough, looking at the underside of various leaves there are the golden, neatly arranged eggs just waiting to hatch. So, it seems if you garden in a place where one of these native squash vines are spreading about like they do, they represent a source of hungry squash bugs looking for more tender summer squash garden variety plants. I immediately disposed of what I had thought of as a friendly neighbor that I had respected for its incredible survival strategy and will to live. Well, on second thought, it will have to live at a more distant location from my garden. I do not think the native squash plant is in any danger of becoming extinct.


You have discovered 2 important things. Delaying planting of squash does not guarantee absence of squash bugs. Several years ago Carol Sutherland, NMSU Extension Entomology Specialist, assured me that squash bugs have more than one generation each summer. The last generation of squash bugs overwinters in garden debris ready to start the first generation for the next year early in the season. This is a good reason to clean up and properly compost garden debris (compost with high temperatures to kill insect eggs). However, since the squash bug can fly, if there are other squash bugs overwintering nearby, you will still have squash bugs in your garden. Some people swear by late planting of squash to avoid the problem, and it apparently works for some, but as you have discovered (and as I have also experienced), they can still attack, infest, and damage your plants even if you plant late.

The second important fact that you learned is that our native coyote gourds are hosts for the squash bugs. Although the squash bugs prefer to infest squash plants (some varieties more than others) the squash bug will find something to eat. If native gourds plants are within a few miles of your garden, the winged pests will often find your garden. They navigate by smell, following the scent of certain chemicals produced by squash and gourd plants. If the coyote gourd, infested debris from squash in a garden last year, or other source of squash bugs are downwind of you garden they will find you. If you are fortunate, the wind will not blow from your garden to a source of infestation, but such good fortune is rare.

Some gardeners have suggested covering the squash plants with floating row cover fabric, but that prevents pollination. If you cover the plants to exclude squash bugs, the gardener must then take the place of the bumblebees and other pollinators that are essential for moving pollen from staminate (male) flowers to pistillate (female flowers). This is possible, but must be done correctly early in the morning while the squash pollen is still viable. If you really like fresh, home-grown squash, it may be worth it.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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