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ENTOMOLOGY AND PEST MANAGEMENT |
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KEY CONCEPTS
- Insects
- Other arthropods
II. Insect Pests of Houses, Pets and Humans
IV. Submitting Insects for Identification
V. Orders of Insects and Their Feeding Parts
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OTHER ARTHROPODS
Though the insects are the largest group within the phylum Arthropoda, there are many other groups which may be considered pests. Master Gardeners may be called on to identify these other animals. You should be able to determine which of these arthropods are beneficial, nuisances or pests.
Other than insects, the following are the most commonly seen arthropods:
- Class Arachnida (a-RACK-nehd-ah). It includes spiders, mites, ticks, scorpions and pseudo-scorpions.
- Class Crustacea (krus-TA-see-ah) which contains aquatic life, such as crabs, shrimp and lobsters. Pillbugs and sowbugs (also called potato bugs) are crustaceans that live on land.
- Class Diplopoda (dip-low-PODE-ah) are the millipedes or "thousand-leggers."
- Class Chilopoda (chi-LOP-oh-da) are the centipedes.
This class is relatively small, but important. They have the following body characteristics:
- two body regions: cephalothorax (head/thorax) and abdomen
- four pairs of legs attached to the cephalothorax
- pincher-like mouthparts
Although spiders frighten people, they are generally helpful to humans. They are shy and only can distinguish objects within a few inches from them. Even poisonous spiders are not aggressive.
It is surprising to many that spiders are predators of insects. You should think of them as pest control specialists. They constantly search for insects. Wolf spiders are special friends of the gardener and farmer. They attack many common garden pests. Spiders can control stored-grain pests, bedbugs, cotton worms and pea aphids, to name a few. Fact Sheet 2060, "Spiders in and Around the House," details the most commonly encountered spiders in Ohio, Reference Ento.1.
The arachnids have the following body parts:
- 2 body segments: head/thorax and abdomen
- 4 pairs of legs
All arachnids have exoskeletons like insects, but they have no antennae or wings. The following illustration shows a typical spider, next to a typical insect.
Most spiders have 8 eyes. The pincher-like mouthparts are modified into hollow fangs which inject venom into prey. Prey consists of insects, mites and other small arthropods.
Females are usually larger than males. Males often leave their webs at mating time and these males may wander into our homes. Females either lay eggs in the web or carry them in a sac on their bodies.
Most spiders live 1 or 2 years. While developing into adults, spiders molt from 4 to 12 times. Spiders can overwinter in any stage of their development.
The most recognized special skill of the spider is its ability to make a web. This is done by silk-spinning glands that are on the tip of its abdomen. The silk hardens on contact with the air. Spiders make silk webs as snares to catch prey and to hold egg sacs. They also use silk lines to travel long distances through the air.
Spiders grow through an incomplete metamorphosis. The hatchlings look like the adult in miniature. Gradually, they grow through several molts to their mature size.
The black widow and the brown recluse spiders are the only poisonous spiders found in Ohio. These spiders are shy and rarely encountered.
The bite of the female black widow or northern widow spider is harmful to humans. Males and baby spiders are harmless. Female black widows rarely leave their webs. They prefer to live on marginal land with sparse vegetation. They build their webs in stumps, hollow logs or piles of debris. Occasionally, they build webs indoors.
Populations of black widows fluctuate from year to year. These spiders are most likely to bite humans when their webs are accidentally disturbed. Details on life cycle, habitat, identification and treatment of bites are explained in Fact Sheet 2061A, Reference Ento.2.
Brown recluse spiders will retreat when disturbed. They live in undisturbed areas near or in homes. They prefer garages, cellars, and attics.
An excellent photograph of a brown recluse spider is in Fact Sheet 203, Reference Ento.3. Brown recluse bites are reported when people put on clothes that have been undisturbed for a long time. A spider may be hiding in the clothing and is squeezed against the person's body when the clothing is put on.
Mites are very tiny or even microscopic. There are more than 30,000 species of mites. In the mite group, there are mites that are HERBIVORES (HERB-uh-vores), CARNIVORES (CAR-nuh-vores), parasitic (pear-ah-SIT-ick), and many that are SAPROPHYTIC (sap-row-FIT-ick).
Spider mites feed on plants. Carnivorous mites eat the flesh of other mites or insects. Parasitic mites (chiggers and ticks) feed on the blood of their host. Saprophytic mites live off dead material. These mites function as decomposers, breaking down organic matter.
Mites are easily overlooked because of their size. Some species even live on minute dust particles and debris in our homes. They are called "dust mites."
About 140 mite species have been identified on house dust. These mites enter our homes on pets, people, food and dust itself. Some of these mites can cause allergic reactions in humans.
Other mites that can be troublesome to humans in Ohio are follicle mites, scabies mites, and grain and mold mites. Fact Sheet 2101 discusses controls.
Spider mites and eriophydic (err-e-o-PHID-ick) mites are found in the landscape and on houseplants. Mites on plants can be controlled by washing them from the plant with a strong jet of water (syringing) or by using a MITICIDE. Miticides include insecticidal soaps, horticultural oils and synthetic pesticides, such as kelthane.
There are two general groups of spider mites in the landscape: warm-season and cool-season. Warm-season mites grow best in hot, dry summer weather, while cool-season mites grow faster during the cool weather of early spring and fall.
Controlling mite populations is difficult. By the time you notice the damage, the population is either extremely large or the mites are no longer active.
Spider mites use their mouthparts to pierce plant cells and suck out the contents. This causes tiny white or yellow speckles. Heavy damage shows up as yellow or bronze areas and damaged foliage often drops from the plant. Infested plants may have fine webs in leaf axils and on the surface of leaves. Plants can be stunted or die. Fact Sheet 2012 covers identification and control of two-spotted and spruce spider mites, Reference Ento.4.
Ticks are blood-sucking mites. The tick most frequently encountered in Ohio is the American dog tick. It lives on humans, dogs and small mammals. It is a vector of the Rocky Mountain spotted fever. This disease is prevalent in the Eastern United States.
Lyme disease is carried by deer ticks. This is a serious problem in the eastern states and is becoming established in Ohio.
Typical habitats for ticks are weedy areas along trails, roadsides and edges of paths. Ticks wait on grass for a host to brush against the vegetation. Once they are on a suitable host, they crawl towards any fleshy area, attach and feed.
Because ticks can carry disease, it is important to understand how to remove and handle them properly. Refer to Fact Sheet 2073, Reference Ento.5, for specific information on ticks.
Chiggers are blood-sucking mites. They are found in many of the same habitats as ticks. These nuisance mites do not carry diseases in Ohio, but their bites cause annoying itching. Chigger immatures are microscopic. Because chiggers cannot be seen easily, being bitten is the only way we learn that an infestation exists. Chigger larvae attack humans by inserting mouthparts into hair follicles or skin pores to feed.
Chiggers are usually a problem in late spring and summer. Their bites can cause intense itching. Fact Sheet 2100 provides details on how to treat bites, identify infested areas and treat them.
Snails and slugs are closely related to shellfish and clams. They belong to the MOLLUSK group. They have unsegmented bodies and usually have a hard shell. Snails have a prominent external shell and slugs have an internal shell.
They both glide upon a slimy liquid they exude. Snails and slugs need damp soil and humid conditions to survive. They feed primarily at night or on cloudy days. They avoid sun by hiding in cracks, holes and under debris, such as mulch, leaves, rocks and boards.
When conditions become very dry, populations of these two garden pests will diminish greatly. Slug and snail populations are usually greatest in spring and fall when conditions are wet. Although they prefer to feed on decaying matter, they also damage live plants. These animals can cause unsightly damage to many ornamental flowers, foliage plants and strawberry fruits. They can be detected by their slime trails and can be seen after dark with the aid of a flashlight.
Mechanical controls include handpicking, traps, and barriers. Biological controls include toads, reptiles, amphibians and ducks. Direct chemical control is usually poison bait. This bait is toxic to other domestic and wild animals, as well as humans. It is critical to know there are two types of pesticide baits: Mesurol and Metaldehyde. Mesurol is not legal in vegetable and fruit crops. Fact Sheet 2010, Reference Ento.6, provides specific products and methods of control.
Although bothersome to some people, both centipedes and millipedes are beneficial to gardeners. Centipedes have one pair of legs per body segment, while millipedes have 2 pairs of legs persegment.
Centipedes are predators of pest insects. Millipedes break down dead plant material. Centipedes move quickly, while millipedes are slow. Household centipedes hunt flies, spiders and other insects at night. They are harmless to humans and help by consuming other unwanted insects in the home. Correcting damp conditions will reduce indoor centipede populations.
Centipedes and millipedes are common in the garden. They rest under boards or in damp soil. They are seen when soil or compost is turned. Millipedes prefer to scavenge dead material, but occasionally will cause damage to plants. Fact Sheet 2067 gives information on how to prevent and control populations.
Sowbugs and pillbugs are crustaceans, closely related to crayfish, shrimp and lobsters. Sowbugs have flattened bodies and two tail-like structures on the rear end. Pillbugs are similar, except they lack the tail-like structures and roll up into a tight ball when disturbed. A common name for sowbugs is "potato bug." However, do not confuse this common name with the Colorado potato beetle which feeds on potato plants.
Sowbugs and pillbugs do not bite humans or cause damage. If present in large numbers, they may be considered a nuisance. They feed on decaying matter and occasionally young plants. Fact Sheet 2072 provides information on life cycle, habits and control.
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