Watch Out for Squash Bugs

For whatever reason, this year seems to be the year for a variety of garden pests, among them, an encounter with squash bugs – so far only one, but I will need to keep an eye out for more. A couple of years ago a friend from work had a huge infestation of them, and she was bothered with them again last year. I had been lucky in that I had never had them in my garden until last year, where I found a few adults, but no eggs or nymphs – I kept watching closely for evidence of these plant-damaging invaders and squashed (no pun intended) them whenever one made an appearance.

According to the website - www.ipm.ucdavis.edu – squash bugs (Anasa tristis) are a common vegetable-garden pest. They feed on the plant by piercing the leaves and sucking the plant's sap, which results in wilting and potential death of the plant. They target plants in the curcurbit family – pumpkins, squash (summer and winter varieties), melon and cucumbers.

When the adults and nymphs suck the plant juices/sap, the leaves lose nutrients and water and become speckled, later turning yellow to brown. Under heavy feeding, plants begin to wilt, and the point of attack becomes black and brittle. Squash bugs may also feed on young fruits, causing scarring and death.

The adult and juvenile (nymphs) squash bugs can be found near the crown of the plant, underneath leaves, or hidden in the soil around the plants. When disturbed they move rather quickly. I have found that they tend to climb up on to the leaves when I am watering the plants to escape the deluge. This makes it easy to spot the adults and quickly dispose of them.

Unmated squash bugs find shelter in the fall under dead leaves, rocks, wood, and other garden debris to survive the winter months. In the spring, they fly from their protective habitat to nearby cucurbits where they feed, mate, and lay eggs.

Starting in the spring, to manage or help minimize the presence of squash bugs, look for squash bugs that may be hidden under debris, near buildings, and in perennial plants in or near the garden. Inspect young plants daily for signs of egg masses, mating adults, or wilting. Place wooden boards throughout the garden and check under them every morning, and then destroy any squash bugs found.

The UC Davis website says the best method for control is prevention through sanitation. Old cucurbit plants should be removed after harvesting is complete. Keep the garden free from debris that can provide overwintering sites for squash bugs. At the end of the gardening season, compost all vegetation or thoroughly till it under. Handpick or vacuum any bugs found under wooden boards. During the growing season, pick off and destroy egg masses as soon as you see them. Use protective covers such as plant cages or row covers in gardens where squash bugs have been a problem in the past and remove the covers at bloom to allow for pollination.

The UC Davis website also states that squash bugs are difficult to kill using insecticides because egg masses, nymphs, and bugs are often hidden and are difficult to reach with sprays. Several insecticides are available that are less toxic to the environment, which include products such as Neem oil, horticultural oil, and canola oil. These soaps and oils are most effective on the smallest nymphs, but good penetration throughout the plant's canopy is essential so that nymphs under the leaves and deep within plants will be covered. Other more toxic pesticides are also registered for use on squash bugs; however, these materials should be used with caution because of negative impacts on bees and beneficial insects such as predators and parasites that help to keep other pest insects and mites in check. In addition, they are not likely to give better control than handpicking combined with softer chemicals.

So far, I have had luck hand picking squash bugs as I find them since I do not seem to have and overwhelming population of them. My friend has had some luck controlling squash bugs with "Captain Jacks Deadbug Brew Flower and Vegetable Garden Dust," which is approved for organic gardening. There is a warning on the label, so care should be taken with this and all pesticides to ensure that damage does not happen to non-target organisms. It is the law to always follow the instructions on the label.