REPORT NO. ZONE Z-3-66 Not for Publication 5Z30 FEBRUARY 1966

BIOLOGICAL EVALUATION OF A RED-HEADED PINE INFESTATION ON THE OCALA NATIONAL FOREST, FLORlDA

by

L. E. Drake and W. H. Padgett

INTRODUCTION

A biological evaluation of a red-headed sawfly infestation on the Seminole Dist:r.ict of the Ocala National Forest, Florida, was made on January Z6 and 27, 1966, by L. E. Drake, Forest and Disease Control Section with assistance from Bascom Perry, Forester, Seminole Ranger District.

The infestation is scattered throughout 14,000 acres of uneven-aged with intermingled slash pine plantations.

This is the first year of defoliation and there is no known history of past sawfly infestations on this area. However, a 3, 000-acre infestation of another sawfly , excitans, occurred in adjoining Marion County in 1963.

TECHNICAL INFORMATION

Causal agent - The red-headed pine sawfly, Neodiprion lecontei (Fitch.).

Host trees attacked - Longleaf pine, Pinus palustris Mill. was the primary host Ppecies. However, light de.foliation was observed on scattered slash pine, var. elliottii Engelm.

Type of damage - The red-headed pine sawfly feeds on the needles of its host causing defoliation. This damage results in growth loss and repeated defoliation may cause mortality. Defoliation was observed on all age classes from reproduction to sawtimber. Complete defoliation wall noted only on sapling-sized trees lZ-15 years old. No mortality was observed• • Biological data - There are, at least, three generations of this insect each year in Florida and feeding apparently continues throughout the winter months. Hy?nenopterous , presumed to be parasites, were observed in association with feeding larvae. However, the effect of these agents on the sawfly population can be determined only by rearing.

No cocoons were found even though larval feeding had been recently completed on all but six trees examined. Larvae from these trees were collected for rearing to determine the sex ratio and the degree of larval parasitism, However, two days after caging, all larvae were dead.

Environmental factors - Normal rainfall conditions have prevailed in the area for the last two or more years. The stand consist• of uneven-aged longleaf pine with intermingled slash pine plantations.

Location and intensity of outbreak - The area is located on the Seminole District, Ocala National Forest, T 17S, R-Z7-Z8E, Lake County, Florida (Figure 1). The outbreak area consists of approximately 14,000 acres, Scattered trees of all age classes from reproduction to sawtimber had been attacked. Defoliation ranged from five to 100 percent and was heaviest on 12.-15 year-old longleaf saplings. Approximately 30 percent of the trees in this class had been attacked,

DISCUSSION

This is the first year. of defoliation on this area, Some growth loss is probable but no mortality was observed or is expected; however, repeated defoliation could cause mortality. ·

All larvae collected for rearing died two days after caging. This and the fact that nC> cocoons could be found in the infested area indicate that a disease could be destroying the sawfly population in the larval stage, Dead larval specime:.10J have been submitted to the Forestry Sciences Laboratory, Corvallis, Oregon, for a diagnosis. When this diagnosis is received, a more definite determination of the present status of this sawfly infestation can be made,

IMPACT OF CONTROL ON OTHER RESOURCES

If_ control measures should become necessary in the future, consideration must be given to wildlife and fishes in the infested area. This area contains streams, camping areas and is part of the managed huntin~ area,

•

2 RECOMMENDATIONS

This infestation should be watched closely into the next generation. If there is no reduction in the sawfly population or if significant tree mortality appears eminent, direct control should be considered.

Any change in the·present statue of the sawfly infestation should be reported to the Zone 2, Forest Insect and Disease Control Section Office immediately.

3 LGke Dorr

Defoliation Area ~

Figure l - - Location of sawfly infeatation, Ocala National Forest, Florida.