Springtails

Introduction

Though considered insects by some people, springtails (Collembolla) belong to a more primitive group of arthropods, called the Ellipura. Springtails inhabit many different regions of the world, and are even able to survive the extreme conditions of Antarctica. To date, 6000 species are known worldwide; however, in North America, fewer than 20 species cause damage to crops. Springtails live in humid environments such as leaf litter, under the bark of the trees, worm beds, snow fields, and nests built by social insects. In indoor environments, these organisms can inhabit dark, humid places such as basements, bathrooms, sinks and drainages. Springtails are thought to be the second most abundant group of soil-dwelling organisms in the world, only after the soil-dwelling mites. In general, springtails can have population densities ranging from 300 million to 1.4 billion per acre depending on factors such as humidity and organic matter content.

Description

Springtails are minute six-legged arthropods with a body size generally ranging from 0.25 to 8 mm long, although some reach up to 10 mm (see photos). These organisms have only 6 abdominal segments, lack wings and their body color varies greatly from white to pale brown to red to purple. In some instances, they may also have elaborate patterns on their bodies.

The word “collembola” originates from the Greek words kola, meaning glue, and embolon, meaning peg, referring to a ventral appendage (i.e., the collophore). The collophore was once believed to serve as an attaching mechanism, but is now believed to have importance in maintaining water balance. The common name “springtail” refers to the ability of these organisms to “jump” when disturbed , or during mating. Springtails can jump (up to 100 mm) with the help of a forked appendage, called the furcula, at the tip of the abdomen (see black&white image at top of page). The furcula is generally bent forward and held close to the underside of the abdomen. The furcula can be rapidly extended backwards propelling the individual into the air. However, in some species this mechanism has atrophied.

Biology and life cycle

Springtails are generally considered to be detritivores (i.e., feed on decaying organic matter), but some species are herbivores or carnivores. Many of these organisms feed on decaying plant material, fungi, bacteria, arthropod feces, algae and pollen. Their mouthparts can be either chewing-biting or piercing-sucking.

Springtails present an ametabolous life cycle, meaning that they do not undergo metamorphosis. Females can lay up to 400 eggs during their lifetime. Eggs are about 0.2 mm in diameter, spherical, and are laid singly or in clusters. After about 10 days, the eggs hatch into juveniles (hatching rate is temperature dependent). Juvenile stages are similar to the adult stages, but they are smaller and without reproductive organs. In about 6 days, and after 5-8 molts, juveniles become adults. Adults will continue to molt, and are long lived with some individuals living for more than one year. An individual may experience up to 40-50 molts during its lifetime.

Damage

As stated before, most springtails feed primarily on decaying organic matter, and are rarely seen as crop pests. However, some species, such as the garden springtail, Bourltiella hortensis Fitch, feed on living plant tissues, generally preferring young leaves. Feeding from these herbivorous species results in small holes and surface scarring on the leaves (see photos, left). The damage resembles that of flea beetles. Roots are also fed on by some species, such as Onychiurus spp. Springtails have been reported feeding on many different vegetable crops, for example: beans, beets, broccoli, cabbage, cantaloupe, carrot, cauliflower, celery, cucumber, lettuce, onion, pea, potato, pumpkin, radish, spinach, squash, tomato and watermelon. Turf and ornamental plants are also sometimes fed on by springtails. In Australia, alfalfa is attacked by the lucerne flea, Sminthurus viridis. Not surprisingly, the humid conditions and abundance of organic matter in mushroom cellars can contribute to outbreaks of Hypogastrura armata on commercial mushrooms. Feeding within a crop often occurs over only a small area, but will occasionally be more expansive, and in rare occasions result in loss of an entire crop.

Management

Springtails can be sampled using visual inspection of plants, pitfall traps, or various soil sampling techniques. Despite the potential for occasional crop damage, and the ability to sample springtails, the authors are unaware of any sampling plans or action thresholds for these pests on any vegetable crops.

Cultural techniques can be used to mitigate potential pest pressure from springtails. To lessen the likelihood of springtails occurring on crops, avoid planting into fields with high levels of organic matter. This includes organic matter from crop residues or organic matter that has been applied to the field. There is also some evidence that soils which produce deep cracks upon drying can promote the survival of springtails during drought conditions.

Insecticide use for springtail management is generally not necessary. However, granular and liquid soil treatments, as well as foliar treatments are available. A variety of products containing active ingredients such as diazinon, chlorpyrifos, malathion, and carbaryl are labeled for use against springtails. However, many of these labels are for use on turf or ornamental plants, not vegetable or field crops. Be sure to read and follow the pesticide label.

Selected References

Capinera, J.L. 2001. Handbook of Vegetable Pests. Academic Press, San Diego, CA.

Cranshaw, W. 2004. Garden Insects of North America: the Ultimate Guide to Backyard

Bugs. Princeton University Press, Princeton, NJ.

Evans, H.E. 1968. Life on a little known planet. E.P. Dutton & Co., New York, NY.

Lyon, W.F. Springtails. Ohio State University Extension Fact Sheet. HYG-2070-98. www.ag.ohio-state.edu/~ohioline/hyg-fact/2000/2070.html