Was cardboard used in that area by any chance? Some gardeners put it down to block turfgrass or weeds from growing up into a raised bed, though your bed sounds like it's on a paved surface. Sometimes gardeners use it to place underneath mulch if covering an area that was excessively weedy (though using cardboard for that purpose is not necessary or even recommended). Termites consume wood, and while they often nest underground and forage through the soil, they must use wood as a source of food. (Cardboard, being derived from wood pulp, can be a suitable food source that also appeals to them.)

If the termites are not originating from inside a house or nearby structure, or are not found invading a nearby structure, intervention is not needed. They can forage up to 200 feet from their actual nest, so there's a possibility they are not originating in your yard if a property line is less than that distance away. While they can destroy wood over time, like the timbers or boards used to line raised beds (especially if they don't happen to be wood treated for ground contact), damage is slow to accumulate, and you would see the deteriorating sections of wood eventually and know which boards to replace. The termites should not damage the vegetable plants themselves. Termites are prey to a wide variety of other organisms, including birds, frogs and toads, and ants, so they will also help to reduce their numbers once any of those predators discover them.

Miri

On 07/11/2024 3:57 PM EDT Ask Extension <<personal data hidden>> wrote:

 

 

Termites could like compost as it can provide the moisture and fiber they need and prefer, but they are likely not coming from any purchased and bagged compost. Termites feed on sources of cellulose which can be found in wood, plants, cardboard, and other materials.

As Miri mentioned there is likely a termite colony nearby, especially if you are seeing termites in your garden year after year. Termites naturally occur in our environment and can forage distances away from their nest, so this is not surprising. The termites may have been attracted to and foraging on the untreated wood frame of your old garden bed, the tree stumps, and/or other materials in the area. Termites do sometimes nest in tree stumps so it would be worth inspecting the tree stump and considering its full removal. Some signs there may be termites in the stump could be the presence of dropped termite wings and/or wood shavings around the base of the stump. As well as looking for any mud tubes.

Some people have been able to lower termite populations in garden beds by applying entomopathogenic nematodes (EPNs). Nematodes are microscopic, whitish to transparent, unsegmented worms that can be used to control pests like termites. Nematodes naturally occur in the soil and have different target hosts depending on the nematode type/group. Nematodes are commonly purchased and used to control different insect pests. Any nematodes labeled to target insect pests like termites would not hurt your plants. More research needs to be done to understand how to best use nematodes to manage termites in garden beds. Current research has shown efficacy of nematodes against termites is variable and this type of control method may need to be used in combination with other controls such as chemical controls for the best results. This Extension page has some guidelines for applying nematodes for termites in garden beds: https://www.aces.edu/blog/topics/crop-production/management-tactics-for-termites-infesting-organic-vegetables/. 

It may be worth contacting professional pest control companies to assess your yard and garden. They would be able to provide treatment recommendations for your yard and assess any further risks/attractants. Most companies provide free estimates, at which time they discuss a treatment plan, cost, and of equal importance, warranties. Compare recommended treatment programs and estimates among several companies. Companies should fully disclose information on the chemical that they will be using in the treatment. 

I would recommend working with a professional pest control company in contrast to do-it-yourself chemical termite treatments as you want to ensure any applied chemical treatments or bait systems do not affect and come into contact with your edible garden plants. For instance, one common do-it-yourself termite treatment product, Termidor is not labeled for food use and thus should not be used in vegetable garden beds. Always read and follow all label directions for safe use of any pesticide.

Maddie