Now that summer is here, insects and spiders are multiplying all around us. Although many of us may be put off by the six-legged predators in our gardens and on our plants,
only a small number of insect species is harmful. Articles appear pointing out beneficial insects like ladybugs, praying mantises, and some wasp species, but there are other arthropods that give us a hand controlling insect pests in the garden. These are the arachnids.
Spiders do an awful lot to keep insects in check. And they also have helpful kin like daddy-long-legs, centipedes, millipedes and many species of mites.
These may look like spiders, but they're not. From summer to fall we encounter them everywhere. We call them daddy-long-legs, a reference to their most notable attribute, or harvestmen because they are most numerous in the fall. They run fast, but
they don't bite. Many species have stink glands at the base of the first pair of legs. Try to pick one up, and you may just catch a leg or two. They break off easily and allow the creature to escape. They cannot be regenerated. Most of the ones commonly found in our area
belong to the family called Phalangiidae. Those with a brownish body with black stripes down the center and along the legs belong to the genus, Leiobunum, while the lighter, reddish-brown members are often Phalangium opilio.
Daddy-long-legs, like many other arachnids, are nocturnal. Most of them eat other insects, spiders, mites, the gills of some fungi (toadstools) and decaying plant matter. Eggs are laid in the soil in the fall and hatch out when the weather warms in
the spring. In our area, most individuals die off in the winter. They like to gather in large groups in the crotch of a tree or some other hollow especially at night or when the temperature dips. This helps them retain the daytime warmth and gets them through the cold snap.
Hundreds of them with their legs intertwined make a memorable sight.
Less visible than the daddy-long-legs, but also related to spiders, are mites. Although many species of mites, especially the spider mites (Family Tetranychidae) suck plant juices and are pests on trees, and crops, others, such as the velvet mite
(Family Trombidiidae), eat insect eggs and are external parasites on many adult insects. These are found in litter on the forest floor or sometimes attached to the leg or wing of an adult insect. They are minuscule eight-legged creatures, measuring about .1 inch, and look
like small red velvet cushions, hence their name. Though they outnumber other arachnids, their small size does not lend to a full study of their impact as beneficial arachnids. Most studies are concerned only with the negative effects on commercial and residential plantings
where harmful species do considerable damage.
The next class is much more noticeable and due to their many legs and speed may be more startling. These are the centipedes. The common house centipede, Scutigera spp., has only fifteen pairs of legs, not the hundred that the name implies. The long
legs are attached to the body segments and hold the brownish body low slung near to the ground. Unlike other arachnids they possess two long antennae which protrude a considerable distance in front of the body. They also possess two compound eyes, like most insects. They
have small jaws beneath the head, which are equipped with poison glands. Due to their small size, the pincers cannot usually pierce human skin (nor can most spiders) and therefore, pose little or no danger. Living for a year or more, they hunt around the walls of our houses
for flies and any other insects they may find.
Digging in the garden you may find, as I have, a soil centipede. These eyeless centipedes have an uneven number of pairs of legs, from 31 to 177 pairs, and live in the soil. They resemble thin reddish, orange wires with many legs and two prominent
antennae on the head. Working their way through loose soil and litter, they devour insect larvae and worms. They have been found as deep as 28 inches in the soil.
The last class of commonly found spider kin is the millipedes. We have all seen these in or near our houses and gardens, sometimes congregating in large numbers. The most commonly found millipedes in our area are members of the order Julida. They
possess a cylindrical body divided into as many as 74 sections, each section bearing two pairs of legs. While they can measure up to three or more inches long, most are one to one and one half inches long. They are dark brown in color. Like the centipedes they possess two
antennae to detect their prey. Millipedes feed on decaying leaf and plant litter. In the compost pile they help break down the material into fertile compost. Millipedes enjoy a damp, dark environment.
Since millipedes and centipedes can occasionally become pests if they occur in excessive numbers in our houses, the easiest way to remove them is to vacuum them up. A mothball or two in the vacuum bag will destroy any insects or eggs picked up. This
method is much easier on the housekeeper and much safer than using sprays and pesticides that may harm children or pets.
When we see any of the above creatures in our gardens or in the underbrush outdoors, we may at first be taken aback by their presence, but we can be assured that they are working for us keeping down the pest population and creating a fertile
environment for our plants.
Read other articles on birds, wildlife & beneficial insects
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