The term occasional invaders includes those pests that often occur in buildings at some stage of their life cycle but that do not usually complete their entire life cycle within the building. Most of these pests live outside of buildings and come indoors only on occasion. Although they may enter in large numbers, they usually do little damage and are considered a nuisance simply because of their presence. Many of these pests enter buildings while they are flying around at night, because they are attracted to lights in or on the home or building (thus the term light-attracted pests).
Many of these pests are most effectively and efficiently managed by eliminating conditions that allow them to harbor and build up to great numbers near the structure. This generally involves some sort of sanitation procedure or basic change in landscaping. Techniques such as caulking cracks and crevices around doors and windows or inserting screening into weep holes of a brick facade on the structure’s exterior can be very useful for long-term relief from these pests. There may be some factor or stimulus that is causing the pests to enter the structure. Other factors that may stimulate pest movement into structures include environmental extremes (such as unusual dry spells), excessive rainfall (and poor drainage adjacent to the foundation), onset of winter (some pests seek to overwinter in structures), or presence of some unusual food source.
Outdoor Centipedes usually live outdoors in damp area, such as under leaves, stones, boards, or tree bark or in mulch around outdoor plantings. When these centipede habitats are near a home’s foundation, centipedes will wander inside, where they may be found at floor level almost anywhere. If provoked, larger centipedes may bite, causing some pain and slight swelling. Actually, their “bites” are not caused by their jaws or mouthparts, but by their front legs, which are modified to look and and function like jaws and contain venom glands. Smaller species are not large enough to penetrate human skin. Centipede bites are usually not serious, but an antiseptic should be used on the wound and a physician consulted in all cases where the skin is punctured.
Centipedes are usually brownish, flattened, and elongate animals that have many body segments. One pair of legs is attached to most of these body segments. They differ from millipedes in that millipedes have two pairs of legs on most segments and bodies that are not flattened. Centipedes range in length from 1 to 6 inches and can run very rapidly.
Centipedes do not eat food supplies or household furnishings. Since they eat insects, spiders and other arthropods, they are beneficial; however, most people consider them a nuisance when they wander indoors and want them controlled.
House Centipedes are the most common pest in many parts of the United States. Unlike most other centipedes, this species generally lives its entire life inside a building.
The body of this centipede is usually only 1 to 1-1/2 inches long at the most, but its fifteen pairs of very long legs makes it seem much larger. The body is grayish yellow with three dark stripes extending along the full length of the back. The legs are quite long in proportion to the body, and have alternate light and dark bands running around them.
In the home, the house centipede prefers to live in damp areas, such as cellars, closets, bathrooms, attics (during warmer months), and unexcavated areas under the house. Eggs are laid in these same damp places, as well as behind baseboards or beneath bark on firewood.
The house centipede forages at night for small insects and their larvae, and for spiders. Although this centipede can bite, its jaws are quite weak. There usually is not more than a slight swelling if bite occurs.
Millipedes normally live outdoors in damp places, such as under decaying leaves and in mulch around outdoor plantings. They feed on damp and decaying vegetable matter as well as on new roots and green leaves. In wooded areas millipedes live in piles of leaf litter. In dry weather they will migrate out of the litter piles as the leaves dry, and they may cross roads and enter buildings in large numbers. This behavior may also occur in lawns that contain thick thatch layers, or yards where large piles of leaves and compost piles are present.
Millipedes, or thousand-leggers, as they are commonly known, are elongate brownish animals that re oval in cross section and appear to have two pairs attached to most body segments. Actually, each apparent body segment consist of two segments that are fused together and appear as one. Millipedes that commonly invade homes are 1/2 to 1-1/2 inches long and tend to coil up when resting.
The house cricket and the field cricket commonly invade homes. When present in large numbers, crickets are considerable annoyance and can cause damage to some fabrics, such as linens, rayon, and furs. They will attack paper, all kinds of foods, and even rubber. However, unless large numbers occur, such damage is usually minor.
Crickets are rather closely related to cockroaches, so they have similar omnivorous feeding habits. The young, or nymphs, look like adults, except that their wings and genitalia are not developed fully.
Earwigs are primarily scavengers on dead animal and plant material, but some species are predators. Other species may actually feed on living plants. They are active at night, and some species are attracted in large numbers to lights. During the day they usually find shelter beneath stones, boards, and debris. Only a few of the winged species are good fliers. Earwigs are often transported great distances in potted plants, nursery stock, or other plant material.
Considerable difficulty has been experienced in the southern United States the striped earwig. It is about 1-inch long, and readily attracted to lights. It produces a strong odor when disturbed or crushed. The striped earwig is lighter in color than the other earwigs, and the pronotum and front wings are usually marked with pale stripes along the edges and in the middle. This insect has the ability to develop large populations within a single season, and it can be a severe pest in new subdivisions or where land is being cleared for new buildings.
Scorpions are quite common in much of the southern and southwestern United States. Most species that enter houses are not very poisonous, their stings being comparable to those of bees or wasps. However, certain species in the desert Southwest can be dangerous, especially to sensitive or allergic people. Most scorpions are active at night. During the day they hide under bark, boards, and rocks or in rubbish. In houses, they are most often found in undisturbed area, such as closets, seldom-used shoes, or folded clothing.
Scorpions feed on small spiders and soft-bodied insects. They will eat other species of scorpions and even small individuals of their own species. They have poor eyesight, so they do not stalk or chase prey but lie in waiting to grab it with their pincers. Small insects are eaten immediately, but larger prey are stung and eaten after they cease to struggle.