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common name: pine sawflies
scientific name: Neodiprion spp. (Insecta: Hymenoptera: Diprionidae)

Introduction - Distribution - Description - Biology - Hosts - Survey and Detection - Management - Selected References

Introduction (Back to Top)

Pine sawfly larvae, Neodiprion spp., are the most common defoliating insects of pine trees, Pinus spp., in Florida. Sawfly infestations can cause growth loss and mortality, especially when followed by secondary attack by bark and wood-boring beetles (Coleoptera: Buprestidae, Cerambycidae, Scolytidae,). Trees of all ages are susceptible to sawfly defoliation (Barnard and Dixon 1983, Coppel and Benjamin 1965).

Larvae of the blackheaded pine sawfly, Neodiprion excitans Rohwer, on Pinus sp.

Figure 1. Larvae of the blackheaded pine sawfly, Neodiprion excitans Rohwer, on Pinus sp. Photograph by Arnold T. Drooz, USDA Forest Service; www.forestryimages.org.

Distribution (Back to Top)

Neodiprion spp. are indigenous to Florida. Host tree specificity and location will bear on sawfly distribution statewide.

Description (Back to Top)

Six species are covered here so there is some variation in appearance. However, an adult female has a length of 8 to 10 mm, with narrow antennae on the head and a stout and thick-waisted body. This is unlike most Hymenopteran insects which have the thinner, wasp-like waist. The background color varies from light to dark brown, with yellow-red-white markings common. The two pairs of wings are clear to light brown with prominent veins.

Adult female Neodiprion sp.

Figure 2. Adult female Neodiprion sp.(Adapted from Atwood 1961). Drawing by Division of Plant Industry.

Adult female redheaded pine sawfly, Neodiprion lecontei (Fitch).

Figure 3. Adult female redheaded pine sawfly, Neodiprion lecontei (Fitch). Photograph by Lacy L. Hyche, Auburn University, www.forestryimages.org.

Adult: The adult male has a length of 5 to 7 mm. The male has broad, feathery antennae on the head with a slender, thick-waisted body. It generally has brown to black color wings, similar to the female.

Adult male slash pine sawfly, Neodiprion merkeli Ross.

Figure 4. Adult male slash pine sawfly, Neodiprion merkeli Ross. Photograph by James Castner, University of Florida.

Adults of the blackheaded pine sawfly, Neodiprion excitans Rohwer.

Figure 5. Adults of the blackheaded pine sawfly, Neodiprion excitans Rohwer. Photograph by Gerald J. Lenhard, Louisiana State University, www.forestryimages.org.

Egg: The egg is small (0.5 mm wide x 1.8 mm long), green-yellow-white color, and ovoid.

Eggs of the redheaded pine sawfly, Neodiprion lecontei (Fitch), in pine needle.

Figure 6. Eggs of the redheaded pine sawfly, Neodiprion lecontei (Fitch), in pine needle. Photograph by Lacy L. Hyche, Auburn University, www.forestryimages.org.

Larva: The length of the mature larva is 18 to 25 mm with variable coloration (see Table 1).

Virginia pine sawfly larva.

Figure 7. Virginia pine sawfly larva. Georgia Forestry Commission.

Virginia pine sawfly larva.

Figure 8. Virginia pine sawfly larva. Georgia Forestry Commission.

Larvae of the redheaded pine sawfly, Neodiprion lecontei (Fitch).

Figure 9. Larvae of the redheaded pine sawfly, Neodiprion lecontei (Fitch). Photograph by Ronald F. Billings, Texas Forest Service, www.forestryimages.org.

Larvae of the blackheaded pine sawfly, Neodiprion excitans Rohwer.

Figure 10. Larvae of the blackheaded pine sawfly, Neodiprion excitans Rohwer. Photograph by Gerald J. Lenhard, Louisiana State University, www.forestryimages.org.

Pupa: The pupa length is similar to that of the adult. The cocoon is light brown to dark reddish-brown, papery, and 3.5 to 6.0 mm wide x 7.1 to 10.0 mm long (Coppel and Benjamin 1965, Thatcher 1971, Wilkinson 1965).

Cocoon of the redheaded pine sawfly, Neodiprion lecontei (Fitch), on branch.

Figure 11. Cocoon of the redheaded pine sawfly, Neodiprion lecontei (Fitch), on branch. Photograph by Jana Albers, Minnesota Department of Natural Resources, www.forestryimages.org.

Adult of the redheaded pine sawfly, Neodiprion lecontei (Fitch), emerging from a cocoon.

Figure 12. Adult of the redheaded pine sawfly, Neodiprion lecontei (Fitch), emerging from a cocoon. Photograph by Arnold T. Drooz, USDA Forest Service, www.forestryimages.org.

Cocoons of the blackheaded pine sawfly, Neodiprion excitans Rohwer, in bark crevices on truck.

Figure 13. Cocoons of the blackheaded pine sawfly, Neodiprion excitans Rohwer, in bark crevices on truck. Photograph by Arnold T. Drooz, USDA Forest Service, www.forestryimages.org.

Biology (Back to Top)

Mature sawfly larvae spin cocoons in the duff or pine litter, mineral soil, or under bark scales. Adult sawflies emerge by removing a cap at one end of cocoon. After mating, female sawflies lay eggs in slits sawed in pine needles. Small larvae feed on outer needle tissues; larger larvae consume entire needles. Most species prefer older foliage, but all foliage is susceptible at end of growing season. Larval colonies may migrate from one tree to another, especially upon complete defoliation of the host tree or high feeding competition. The number of sawfly generations (one to four) varies from year to year and according to species. Larvae may diapause (a survival behavior for adverse conditions) for more than one year (Coppel and Benjamin 1965, Wilkinson 1980).

Cocoons of the blackheaded pine sawfly, Neodiprion excitans Rohwer. Adults have emerged from pupal cases with the ends of the cases missing. Openings in the sides of cases indicate the emergence of a parasite.

Figure 14. Cocoons of the blackheaded pine sawfly, Neodiprion excitans Rohwer. Adults have emerged from pupal cases with the ends of the cases missing. Openings in the sides of cases indicate the emergence of a parasite. Photograph by Arnold T. Drooz, USDA Forest Service, www.forestryimages.org.

Adult female redheaded pine sawfly, Neodiprion lecontei (Fitch), ovipositing on pine needle.

Figure 15. Adult female redheaded pine sawfly, Neodiprion lecontei (Fitch), ovipositing on pine needle. Photograph by James McGraw, North Carolina State University, www.forestryimages.org.

Hosts (Back to Top)

All southern pines, Pinus spp., are susceptible to sawfly infestation.

Oviposition damage to pine needle by the blackheaded pine sawfly, Neodiprion excitans Rohwer.

Figure 16. Oviposition damage to pine needle by the blackheaded pine sawfly, Neodiprion excitans Rohwer. Photograph by Arnold T. Drooz, USDA Forest Service, www.forestryimages.org.

Typical straw-like feeding damage caused by the redheaded pine sawfly, Neodiprion lecontei (Fitch).

Figure 17. Typical straw-like feeding damage caused by the redheaded pine sawfly, Neodiprion lecontei (Fitch). Photograph by G. Keith Douce, University of Georgia, www.forestryimages.org.

Straw-like feeding injury caused by young larvae of the Virginia pine sawfly, Neodiprion pratti pratti (Dyar).

Figure 18. Straw-like feeding injury caused by young larvae of the Virginia pine sawfly, Neodiprion pratti pratti (Dyar). Photograph by G. Keith Douce, University of Georgia, www.forestryimages.org.

Severe pine defoliation caused by the Virginia pine sawfly, Neodiprion pratti pratti (Dyar).

Figure 19. Severe pine defoliation caused by the Virginia pine sawfly, Neodiprion pratti pratti (Dyar). Photograph by Caleb L. Morris, Virginia Department of Forestry, www.forestryimages.org.

Survey and Detection (Back to Top)

Early damage is evidenced by reddish-brown strawlike remains of needles that are incompletely consumed by young larvae; older larvae leave only short stubs. Partially defoliated branches often have a "bottle brush" appearance. Sawfly colonies may consist of a few to over a hundred individuals. Upon disturbance, larvae may drop from branches or assume a U-bend by raising head and abdomen. An oral exudate, which can paralyze insectan parasites and repel predators, often accompanies such displays (Barnard and Dixon 1983, Coppel and Benjamin 1965).

 


TABLE 1. Description of pine sawfly larvae, Neodiprion spp., in Florida.

Common Name Species Description Host Trees1

slash pine sawfly

Neodiprion merkeli
Ross

Two-tone head (red above, black below); yellow-green body with two faint black stripes and a large black spot on hind end of each side

slash pine
redheaded pine
sawfly
Neodiprion lecontei
Rohwer
Red head; whitish or yellowish green body with three rows of irregular black spots; large black spot on hind end of each side longleaf pine,
slash pine
blackheaded pine
sawfly
Neodiprion
excitans Rohwer
Shiny black head; olive-green body with two black stripes and row of black spots; large black spot on hind end of each side loblolly pine,
pond pine,
sand pine,
spruce pine
Virginia pine
sawfly
Neodiprion pratti
pratti (Dyar)
Black head; pale green body with two black stripes and a row of black spots on each side of the body loblolly pine,
Choctawhatchee
sand pine
a pine sawfly Neodiprion
virginianus Ross
Black head; row of distinct, nearly square black spots on each side of the body Ocala sand pine
spruce pine Neodiprion warreni
Ross
Black head; two dark stripes on each side of the body spruce pine
Abbot's sawfly Neodiprion abbotii
(Leach)
Brown-black head with a white spot on the front; yellow to pale green body with two dark green stripes on each side of the body loblolly pine,
longleaf pine,
shortleaf pine,
slash pine


1 Choctawhatchee sand pine = Pinus clausa var. immuginata D.B.Ward; loblolly pine = Pinus taeda L.; longleaf pine = Pinus palustris Mill.; Ocala sand pine = Pinus clausa var. clausa (Chapm.) Vasey; pond pine = Pinus serotina Michx.; shortleaf pine = Pinus echinata Mill.; slash pine = Pinus elliottii Engelm.; spruce pine = Pinus glabra Walt.


Frass under tree resulting from feeding by larvae of the redheaded pine sawfly, Neodiprion lecontei (Fitch).

Figure 20. Frass under tree resulting from feeding by larvae of the redheaded pine sawfly, Neodiprion lecontei (Fitch). Photograph by G. Keith Douce, University of Georgia, www.forestryimages.org.

Management (Back to Top)

Suppression of sawfly populations by insecticides is usually successful. However, consideration should be given to conserving natural enemies (small mammals, birds, insects) through minimal insecticide use and preservation of cypress-hardwood pond stands around pine plantations. The appearance of numerous dead larvae hanging from needles, i.e., virus-infected, usually signals the collapse of a sawfly outbreak. Sawfly outbreaks are cyclical - an eight to 10 year interval is common. A fully stocked stand and promotion of early crown closure minimizes risk of sawfly damage in pine plantations (Wilkinson 1980).

Selected References (Back to Top)