Cicadas belong to the insect sub-order Homoptera. Generally, cicadas are called either annual or periodical. The annual cicadas are present each year and their shells can be seen attached to the trunks of trees (Figure 103). The periodical cicadas emerge in mass either on a 13 or 17-year cycle (Figure 104). Three species with 13-year cycles and three species with 17-year cycles represent the genus Magicicada. Generally, the 17-year broods are northern and the 13-year broods are southern. The last 13-year brood emerged in Georgia in 1998 and the 17-year brood in 2004.
At the end of the 13- or 17-year cycle the brood emerges between May and June thus completing the cycle. The annual cicadas better known as “dog day” cicadas belong to the genus Tibicen and are found throughout the U.S. in late summer to early fall every year although their life cycle requires 4-5 years for development. Twigs and branches can be severely damaged by cicadas but trees appear to recover. Lace bugs are unique in appearance by possessing a hood-like extension of the pronotum that covers the head (Figure 106). The wings are reticulated giving the bugs a lace-like appearance. The sycamore lace bug is a very common pest of the sycamore tree and has been recorded feeding on mulberry, ash and hickory.
The bugs normally increase during early spring and summer, principally on weeds. During droughts or in fields where herbicides have been used, weeds are either absent or less succulent and the bugs migrate to other hosts such as pine. Damage is done by their piercing-sucking mouthparts. They remove sap from the needles causing the needles to wilt and die. The adults are small, averaging about 3 mm in length. Both adults and nymphs overwinter among plant remnants and become active in early spring. Eggs are laid in the soil and on plants low to the ground and hatch in about four days. The nymphs feed for about three weeks before transforming to adults. In Georgia there are at least 4 generations per year with a fifth likely. Little is known about the effects the false chinch bug will have on containerized longleaf pine seedlings. Heavy seedling mortality has occurred in Georgia throughout the Coastal Plain. Damage appears to be heaviest in fields where herbicides were broadly applied as opposed to band applications. Harrowing of fields before planting is likely to kill many over wintering adults and nymphs, but it may not be practical because of the migration habits of the bugs particularly during droughts. Others are likely to fly and crawl from adjoining fields after the pines have been planted. This is particularly true when drought has desiccated weeds and other host crops. Insecticides are effective but may not be warranted when rainfall has been normal and there is an abundance of succulent weeds nearby. Seed bugs are very injurious to pine seed in seed production orchards. First year conelets often abort due to seed bug feeding. Cones that don’t abort either shrivel or produce low yields of sound seeds. The shieldedbacked pine seed bug, Tetyra bipunctata, is sometimes hard to spot since it hides very quickly if disturbed (Figure 109). It has the typical stink bug appearance and varies from light brown to reddish-brown in color. The leaffooted pine seed bug, Leptoglossus corculus has leaf-like hind tibiae that easily identify it (Figure 110).
Scale insects can be injurious to pines in seed orchards and a nuisance in Christmas tree plantations. This group of insects is very large; containing minute and highly specialized individuals. Different species attack different parts of the host, branches and twigs being frequently infested. Development of scale insects varies somewhat with different species. In most cases development is rather complex. The first nymphal instars (crawlers) have legs, antennae, and are fairly active. After the first molt the females lose their legs and antennae and become immobile and sessile. A waxy covering is then secreted over their body. This covering may be in the form of powder, plates or drops of resin. The females remain under the covering where they lay eggs and give birth to living young (viviparously). The eggs are never laid in the open. The males develop much like the females having several scale-like nymphal instars; the last instar is often called a pupa. There may be one to six generations per year varying with species and geographical location. Scale insects extract sap from plant parts thus causing devitalization and death of the infested parts. Some scales produce galls. The woolly pine scale, Psuedophilippia quaintancii, produces a white, cottony, waxy secretion that accumulates on the needles (Figure 111). During heavy infestations trees appear to be covered in snow. Needles and twigs are fed on. Scales can cause needle yellowing, stunted growth, dieback and heavy sooty mold. The cottony maple scale, Pulvinaria innumerabilis, feeds on maples, honey locust and other hardwoods. Other common species of soft scales are the pine tortoise scale, Toumeyella parcivicornis and the oak lecanium scale, Parthenolecanium quercifex, and the pine needle scale Chionaspis pinifoliae (Figures 112-114). Examples of armored scales are the pine twig gall scale, Matsucoccus gallicolus. The pine mealybug, Oracella acuta is a scale affecting loblolly pine.
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Forest Pests: Insects, Diseases & Other Damage Agents |
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