. An annotated list of the important North American forest insects. Forest insects. THE SOITTHET^N PINE BEETLE 11 Tills difFerenco in liabits is made use of in control of beetle out- breaks. The soutlieni })ine beetle attacks and kills healthy, vioorous j^reen pines of practically all species and sizes within its range, Shortleaf pine ^ is probably its most favored host, while longleaf pine' is least favored and rarely attacked. The only trees not at- tacked by it are the smaller pines below 2 inches in diameter (breast hei<»;ht) and less than 20 years old. The Ips beetles attack dj^ing tre
. An annotated list of the important North American forest insects. Forest insects. THE SOITTHET^N PINE BEETLE 11 Tills difFerenco in liabits is made use of in control of beetle out- breaks. The soutlieni })ine beetle attacks and kills healthy, vioorous j^reen pines of practically all species and sizes within its range, Shortleaf pine ^ is probably its most favored host, while longleaf pine' is least favored and rarely attacked. The only trees not at- tacked by it are the smaller pines below 2 inches in diameter (breast hei<»;ht) and less than 20 years old. The Ips beetles attack dj^ing trees, recently killed trees, and trees Aveakened by some other agency. Although insects of this latter group may hasten the death of some trees, they seldom are the cause of it except under unnatural conditions. Trees seriously affected by drought, fire, gir- dling, or primary in- sects may be success- fully attacked by Ips. The turpentine beetles (fig. 11, B) are similar in form to the southern pine beetle but are about twice as large, being about one-fourth inch in length. They often attack the bases of pines surrounding n e w 1 y constructed buildings or camps, or anywhere where t h e cutting or wounding of pines has taken place. They are rarely able to complete their life cycle in green trees and are usually drowned out by the flow of pitch. Normally they breed in stumps and felled logs and are not capable of killing trees. Occasion- ally, however, they at- tack weakened, dying, and girdled trees and develop healthy broods in them. In girdled trees they attack belo\7 the gridle, where growth has ceased. Trunks of standing trees aro seldom attacked by this beetle at points more than 6 feet from the ground. Their work is readily detected, because there are large pitch tubes near the base of attacked trees (fig. 15), and when the bark is removed their long galleries, about a half inch wide and filled with pitch and borings, are exposed. The grubs, working. Figure 11.—Adn t ha
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Keywords: ., bookauthorhopkinsadandrewdelmar, bookcentury1900, bookdecade1900
