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Sawflies belong to the same order as bees and wasps and like other members of that order, the adults have two pair of transparent wings hooked together. They are given the name sawflies because of the females ovipositor (egg laying apparatus ) that is saw-like and used to cut pockets into plant tissue for egg laying. The larvae, which look like caterpillars but have more than 5 pair of prolegs and do not have crotchets, are called false caterpillars or slugs and are usually covered with a slimy coating. Most live on exposed foliage, either singly or in groups, some are leafminers, while a few are web spinners. It is the larvae stage of the sawfly that is destructive to plants. The larvae feed on the foliage of many kinds of shade trees, conifers and shrubs, some of which include arborvitae, ash, birch, balsam fir, several cane fruits, butternut, crabapple, dogwood, elm, hickory, larch, juniper, mt.ash, oak, several pines, especially mugho, roses, several spruces, walnut, willow and various stone fruits. For control apply a contact insecticide when first noticed, sawflies can defoliate a plant quickly.
Scale insects are a very large group of plant feeding insects that feed by sucking juices from plant tissue. They spend most of their lives affixed and stationary to leaves, branches, twigs or the trunk of their host plant. Scale insects can be divided into two basic groups, armored scales and tortoise or soft scales. Armored scales are covered with a distinct hard shell or scale of hard wax that is separate from the body. Plant injury is caused mostly by the wingless females. The young move about briefly in what is known as the crawling stage and after they find a suitable resting location, they insert their threadlike mouth parts through the epidermis of the plant tissue and start sucking plant juices. The females molt twice, but always remain under their shells and each time the cast skins are shed, they are mixed with a wax exuded from the body wall to form their shell. They remain in the same spot for the rest of their lives, laying eggs and in some cases living young, under the shell. The males have an elongated body and are smaller and after 4 molts become a two-winged yellow insect with legs, antennae, but no mouth parts that resembles a small gnat with a long appendage at the end of the abdomen. They can move about and mate with the females. The soft scales or tortoise scales are not covered by a separate shell, but the protective shell is made of their hard chitinous body wall and may be as hard as the shell on an armored scale. They also keep their small legs but move so sluggishly, they appear stationary. Scale infestations, especially when heavy are not only unsightly, they can kill branches, stems or entire plants. On some plants with heavy foliage scales may be hard to see or notice, early symptoms that may indicate scales are yellowing of foliage or ants traveling near and within the branches of the plant. Some species secrete honeydew which attracts ants and encourages the growth of sooty mold fungus. For biological control of soft scales attract native predatory beetles such as soldier and lady beetles, or parasitic wasps such as Metaphycus helvolus. For soft or armored scales predatory beetles Chilocorus nigritus and Lindorus lophanthae can be released. Dormant oil can also be used for either type of scale. It is difficult to control armored scale with insecticides due to their hard protective shells, but most scales can be controlled in the crawling stage by spraying a contact insecticide such as Malathion*.
Slugs and snails, although not insects are included here due to the plant injury that they can cause in the garden. They are mollusks, belonging, along with clams, oysters and other shellfish to the large animal phylum Mollusca. Members of this group are characterized as those animals with soft, unsegmented bodies and usually protected with a hard shell. Slugs and snails belong to the Gastropoda class which means "stomach in the foot". Slugs and snails are similar, the only difference is, that a slug doesn't have a shell, or it has a shell that has been reduced to a very small plate and is located internally on its back. Slugs can range in length from 1/4" to 8-10" long and are usually whitish yellow to black in color. Without a shell for protection, they need a cool, damp place to hide in the daytime. At night, both slugs and snails begin to feed rasping holes in the foliage of tender plants and in some cases totally devouring seedlings. They will also feed on bulbs. Slugs and snails can be found throughout North America, but are most destructive to plants in wet regions or during wet rainy weather. Adults lay clear eggs in jelly-like masses in moist soil under logs, stones or any kind of debris in the Spring and Fall, eggs hatch in 2-4 weeks and the young may take from 5 months to 2 years to reach maturity. For control one can protect seedlings or plants with tender foliage such as hostas with a wide band of cinders, wood ashes, or diatomaceous earth, but this will need to be replenished regularly, especially after a heavy rain. Slugs and snails will not crawl through sharp edged materials or if they do they will become injured and die.
These soil pests are related to crayfish and are not insects, but members of the Crustacea family, which includes arthropods having 2 pair of antennae and at least 5 pair of legs. They have oval gray to brown bodies, are 1/4"- 1/2" long and have 7 pair of tiny legs. Their jointed armor, is nothing more than abdominal segments fused and compressed together. Not all species will roll up into a ball when disturbed, the common pillbug ( Armadillidum vulgare ) will and has been given the common name of Roly-Poly. Sowbugs and pillbugs breathe by means of gills and prefer dark, damp, moist places for hiding and feeding. They can most often be found scavenging on rotting vegetation, under decayed wood or other materials, in manure or even under that beautiful flower pot on your patio. They are the buzzards of the soil, feeding on all kinds of decaying matter and can be found most everywhere in the garden throughout North America. With high enough populations, they can become quite injurious to seedling, eating roots and girdling young stems. In unsanitary greenhouses they can wreak havoc. One can control them to a point, possibly in greenhouses or near entrances to your home, but the fact of the matter is, they are just as much a part of the garden as the sun is to the sky and regardless of what is recommended to eradicate them, you will never entirely rid yourself of them. If they have become a real nuisance, you may want to tidy up the place a bit, remove fallen leaves, debris and the like, this will not prevent them, but it will help to curb their populations. Malathion, Sevin and Lindane are recommended for their control. Diatomaceous earth can also be an effective control around doorways or foundations.*
Spanworms are caterpillars with the same looper-like habit as cankerworms, just that they happen to be called spanworms. (see cankerworms for description )
Spittlebugs, although not true bugs, are closely related to cicadas and leafhoppers and sometimes referred to as froghoppers. Adults are frog-faced and oval in shape, 1/4"-1/2" long, black, gray, brown or tan. Nymphs are similar to adults, but wingless and yellow to yellowish-green in color. Eggs are laid in the fall in field stubble, overwinter and hatch about mid-April. An unusual characteristic of these insects (and hence the name) is the frothy mass known as spittle, found clinging on the foliage and branches of the plant. This frothy mass is only produced by the nymphs to keep them moist, protect them from the sun and to provide protection from many natural enemies. This spittle is a combination of air bubbles trapped in fluids discharged from the anus and a mucilaginous substance released by special epidermal glands. The size of the mass depends on the species, the size of the nymph or the number of nymphs feeding at the site, there may be one to several nymphs per spittle mass. Damage to plants results from both adults and nymphs sucking plant juices as they feed. On plants affected by the spittlebug you will notice stunting, wilting and distorted and discolored foliage. For the most part, most spittlebugs do not cause any appreciable injury to plants, but their spittle masses can become unsightly. The most damaging species are the Saratoga spittlebug found from New England to Florida, west to the Great Lakes states, seriously affecting jack and red pines. The most abundant, widespread and most common species is the Meadow spittlebug, known to feed on over 400 species of garden and forage plants, they are especially damaging to strawberries. |
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Sawflies -
Scale -
