Cranberry cultivation is a cornerstone of agricultural industry in regions like North America, where the conditions are ripe for its growth. However, maintaining the health and productivity of these crops is a continual challenge, particularly when it comes to managing pests.

Enter cranberry field spiders—nature’s form of pest control.

These spiders are are pivotal in maintaining the health of cranberry crops through natural predation. By feeding on a wide range of insects such as aphids, leafhoppers, and beetles, they help reduce the reliance on chemical pesticides, which can lead to a healthier crop and environment.

Understanding Cranberry Fields

Cranberry cultivation is different from how most other crops are grown. They are typically grown in what are commonly referred to as cranberry bogs or marshes. These bogs are a special type of wetland that has been adapted specifically for growing cranberries.

Despite what some might think, cranberries don’t grow underwater. Cranberry plants form vines which spread out on the ground like a carpet. These vines produce pink flowers that turn into the red cranberries we know. These vines thrive in the unique conditions of the bog, which include the acidic, peat-rich soil and the consistent moisture that is maintained in the bog environment.

When it’s time to harvest the cranberries, the bogs are flooded. The fruit is dislodged from the vines using equipment referred to as egg-beaters. The cranberry vines survive the flooding without being damaged and the cranberries, which float, are gathered up easily from the surface of the water.

Cranberry Bog Spider Species

Cranberry fields host a variety of spider species, each of which controls different pest populations.

Wolf Spiders (Family Lycosidae)

Ground dwellers by nature, wolf spiders do not create webs. Instead, they hunt pests on foot, showcasing their agility and speed. They range from 0.4 to 1.4 inches (10 to 35 mm) and are characterized by their robust bodies and excellent eyesight. These spiders patrol the cranberry field floor, preying on beetles, earwigs, and other ground-level pests.

Orb-Weaver Spiders (Family Araneidae)

These spiders are among the most visually striking with their wheel-shaped webs spanning between cranberry plants. Typically measuring between 0.2 to 1.2 inches (5 to 30 mm) in body size, orb-weavers use their silk to trap flying insects such as moths and mosquitoes. Their webs are engineering marvels, often rebuilt daily to ensure maximum efficiency.

Jumping Spiders (Family Salticidae)

Small but mighty, jumping spiders have a body size of about 0.1 to 0.8 inches (3 to 20 mm). Known for their vivid colors and precise movements, they hunt during daylight, using their exceptional vision to spot prey from a distance before leaping to capture it. Their diet includes smaller insects and helps control populations of leaf and fruit pests.

Crab Spiders (Family Thomisidae)

Masters of camouflage, crab spiders often measure between 0.1 to 0.5 inches (2 to 12 mm). They typically wait on cranberry flowers or leaves, blending seamlessly into their surroundings until an unsuspecting insect comes within reach. Their presence helps manage pollinator pests and other insects that could damage the cranberry blossoms.

Do Spiders Crawl on Workers During Flooding?

When cranberry bogs are flooded, the spiders in the field might seek higher ground or move away from the water. While some spiders might end up on workers, it’s generally not in large numbers, nor is it something workers report as a major problem. While a few spiders may end up on workers, it’s not a significant or frequent issue during cranberry harvest.

Furthermore, the spiders commonly found in cranberry bogs are not dangerous to humans. Wolf spiders, orb-weavers, jumping spiders, and crab spiders are generally harmless. The vast majority of spider bites are mild, causing little more than minor irritation. Overall, cranberry bog spiders are not a cause for concern for workers.

Challenges and Considerations

The benefits of utilizing spiders for pest control in cranberry fields extend beyond just reducing pest populations. This method of pest control is sustainable, reducing the carbon footprint associated with producing and applying chemical pesticides. Economically, it can also reduce costs for farmers, who may rely less on purchasing pesticides.

While the advantages are clear, relying on spiders for pest control in cranberry fields does present challenges. Spider populations can fluctuate due to various factors including weather, availability of prey, and human activities. Their effectiveness can also be limited if not integrated properly into broader farm management practices. Farmers must consider these dynamics and possibly support spider populations by protecting their habitats and avoiding pesticides that can harm them.