What are pine sawflies and why are they good models for evolutionary research?

N. lecontei is widely distributed throughout eastern North America, where it feeds on many different native and introduced pine species. Adult females lay many eggs per needle, usually depositing all of their eggs in a single branch tip. Larvae feed gregariously and then spin cocoons in the soil. They diapause as prepupae within cocoons and have 1-5 generations per year, depending on latitude.

Color of full-grown larvae: red head and bright body (yellow or white) with up to 4 paired rows of squarish black spots and a dark blotch at the end of the body.

Photo: Robin Bagley

N. pinetum is found throughout the range of its only host plant, eastern white pine (from GA to Canada). Females lay 1-3 eggs per needle, usually clustering their eggs in a single branch tip. Larvae feed gregariously. This species overwinters as a prepupae in the cocoon and has 1-3 generations per year.

Larval color: black head and white body (sometimes yellowish) with 2 paired rows of squarish black spots and a dark blotch at the end of the body.

Photo: Ryan Ridenbaugh

N. virginiana is a specialist on Virginia pine. Its known range includes KY, TN, NC, WV, VA, MD, and PA. It lays many closely spaced eggs per needles and feeds gregariously. It overwinters as a prepupa in the cocoon and has 1-3 generations per year.

Larval color: black head, bright white body, a row of black spots along each side, with minimal pigmentation on the back (except a dark blotch at the end).

Photo: Robin Bagley

Originally lumped together with N. abbotii, DNA evidence revealed that N. fabricii is a distinct species. It appears to be widespread in the Southeastern US (FL, GA, TN, AR, VA, NC and likely other states) and has been collected on shortleaf and loblolly pines. It feeds in small groups and likely overwinters as a prepupa in the cocoon.

Larval color: black head, often with a light areas in the middle of the head and above the mouth. Body is whitish with 4 green stripes along back, a green line above prolegs, and distinctive green coloring between the back stripes and proleg stripe.

Photo: Katherine Brundrett (iNaturalist)

Diprion similis, native to Europe and Asia, was first recorded in the eastern US in 1914. It has since spread throughout much of the eastern US and Canada, and was recently recorded in WA. In its native range, it feeds on a number of different pines, but it is most abundant on eastern white pine in North America. Females lay multiple eggs per needle in a long trench overlaid by a frothy substance. Larvae overwinter as prepupae in cocoons, and there are 1-3 generations per year.

Larval color: black head and a distinctive mottled appearance of black, white, and yellow colored areas.

D. similis is in the same subfamily as Neodiprion and is currently the only non-Neodiprion we are working on.

Photo: Sandra Mak (iNaturalist)

N. excitans is widespread in the southeastern US (VA to FL, west to TX), where it feeds on several different pine species. It has also been reported from Central America, but this could be an undescribed species. Females lay one egg per needle, located near the needle fascicle. Eggs are clumped onto branch tips and larvae feed gregariously. N. excitans typically overwinters as prepupae in cocoons and has 4-5 generations per year, but has been reported to overwinter at other stages.

Larval color: Greenish body with black heads, 2 pairs of light black longitudinal stripes, with black spotting overlaid on the lateral stripes and black blotch at the end of the body. Generally lacks a stripe above prolegs.

Photo: Clayton Jones (iNaturalist)

N. hetricki occurs in the SE US (GA, TN, NC, SC, VA) on loblolly and pond pines. Adults emerge in fall and females lay a single egg per needle, but tend to cluster eggs on a single branch tip. Eggs overwinter in the pine needles and gregarious larvae hatch in late Spring. Has 1 generation per year.

Larval color: white body, solid black head and distinctive black markings, including a pair of thick dorsal stripes, a lateral row of dark spots that tend to bleed together, a line above the prolegs, a dark blotch at the end of the body, and two dark spots above the thoracic legs.

Photo credit: Tim Tigner

N. swainei is abundant in the Lake States and eastern Canada, where it feeds primarily on jack pine (occasionally attacking other pines as well). Females tend to prefer mature pines, lay a single egg per needle, and cluster eggs in a single branch tip. Larvae feed gregariously and overwintering occurs as prepupae within cocoons. 1 generation per year.

Larval color: Usually yellow bodies (but sometimes white), with red heads, two light black dorsal stripes, an incomplete (usually) row of light spots along the sides, no line above the prolegs, and a pair of egg-shaped spots at the end of the body.

Photo: Robin Bagley

N. pinsurigidae occurs in the northeastern US, where it feeds on pitch and shortleaf pines. Oviposition is similar to swainei and excitans (1 egg per needle, clustered on branch tips), larvae feed gregariously, and overwintering occurs in the prepupal stage.

Larval color: white to dull green body, black head, a pair of light black dorsal stripes, a lateral row of spots (partial or complete), a black splotch at end of body, and no line above prolegs.

Photo: Robin Bagley

N. abbotii is widespread throughout eastern North America, from FL to Canada, and west to TX. It feeds on many different native pines (except white pine). Females lay eggs in rows, but tend to spread them across multiple branch tips, making small larval groups. Larvae feed gregariously at first, but tend to disperse with age. This species overwinters as a prepupa and can have multiple generations per year.

Larval color: white body, black head (sometimes brown), sometimes with light areas in middle and above mouth. Four green to black dorsal/lateral stripes with tail spot absent or less pronounced than other species. Tend to have a line above the prolegs, with less pigmentation between stripes than N. fabricii.

Photo: Piotr Naskrecki

N. nigroscutum feeds on jack pine (and sometimes red pine) in the Lake States and Ontario. Females lay eggs in rows, but spread their clutch out across multiple branch tips, resulting in small larval colonies. Overwinters in the prepupal stage and has 1-2 generations per year.

Larval color: head can be reddish brown, black, or two-tone, body can be white or yellow, 4 dorsal/lateral green stripes and a line above the prolegs, with little to no pigmentation in between. Tail spot is absent or indistinct.

Photo: Robin Bagley

N. pratti is widely distributed across eastern North America, where it feeds on many different native pines (except white pine). It is broken into 3 subspecies on the basis of color and geography: N. pratti pratti occurs from North Carolina to New Jersey and west to Illinois (common name: VA pine sawfly); N. pratti paradoxicus occurs from MD to Nova Scotia and Ontario; N. pratti banksianae occurs in SE and central Canada and the Lake States. Females lay 2-5 widely spaced eggs per needle and group them on branch tips. Larvae feed gregariously and overwintering occurs in the egg stage, so there is only 1 generation per year.

Larval color: Black heads and yellowish green body with highly variable markings. Generally there is a dark tail spot and four longitudinal black/gray stripes, with the bottom pair of stripes solid or broken into spots. Darker individuals tend to have a line above the prolegs, with some additional pigmentation along the sides. Photo depicts dark N. pratti pratti.

Photo: Jameson van Vegten (iNaturalist)

N. maurus feeds on jack pine in southeastern Canada and the Lake States. Eggs are laid in rows in needles and grouped in branch tips. Larvae are gregarious. This species, a close relative of N. pratti, has a very unusual life history in which it overwinters as an adult within the cocoon. 1 generation per year.

Larval color: pale body and black head, a dark tail spot, two longitudinal black stripes flanked by two longitudinal rows of dark spots (one on each side), and a light line above the prolegs. Resembles spotted morph of N. pratti.

Photo: Robin Bagley

N. taedae is broken into two subspecies based on geography. N. taedae linearis occurs in AR, LA, TX, MS, MO, OH, and IL. N. taedae taedae occurs from eastern VA to ME. Throughout the range, loblolly pine is the preferred host, although shortleaf and VA pines are also attacked. Females lay 6-8 widely spaced eggs per needle and cluster eggs on branch tips. Larvae feed gregariously and overwintering occurs in the egg stage, so there is only 1 generation per year.

Larval color: reddish brown heads with pale bodies. A pair of greenish gray longitudinal stripes, flanked either by an additional pair of stripes (linearis) or by a row of dark spots on each side (taedae). Dark tail spot and line above prolegs are also present.

Photo: Dr. Mike Merchant (Texas A&M AgriLife Extension)

N. warreni has been collected in FL, GA, AR, and probably occurs in other Gulf Coast states. It has been collected on spruce, shortleaf, sand, and loblolly pines. It lays many eggs per needle and larvae feed gregariously. Overwintering occurs in the prepupal stage, so there are likely multiple generations per year.

Larval color: black or red head, white body, dark pigmentation that includes: a thick pair of dorsal stripes, a row of lateral spots that tend to blend into each other, a line above the prolegs, dark blotch at the end of the body, and sometimes additional dark areas along the sides.

Photo: Ashleigh Glover

N. knereri used to be lumped with N. virginiana, but was described as a distinct species in 2012 (based on DNA evidence and then some morphological traits). So far, this species has only been recorded on sand pine in Florida. Larvae are gregarious and overwintering occurs in the prepupal stage.

Larval color: very similar to N. virginiana. Black head, white body, a pair of faint dorsal stripes, black blotch at end, and dark black spots along the side.

Photo: Jeff Eickwort

N. rugifrons is found in southern Ontario and the Lake States, where it feeds on jack pine. Females lay multiple eggs per needle and deposit their eggs in clusters. Larvae feed gregariously and overwintering occurs as prepupae. 1-2 generations per year.

Larval color: red head, whitish body, pigmentation that can be quite dark and includes: a pair of thick dorsal stripes, lateral row of spots that often merge together, a dark spot at the end of the body, a thick line above prolegs, and often extra pigmentation between the lateral spot/stripe and the proleg line. Similar to N. warreni.

Photo: Robin Bagley

N. dubiosus has a very similar distribution to N. rugifrons and is often found on the same trees. It occurs in the Lake States and southern Ontario on jack pine. Females lay eggs in rows that are clustered on branch tips. Overwintering is in the prepupal stage, allowing up to 2 generations in southern parts of the range.

Larval color: reddish brown head, yellowish body, a pair of dorsal stripes, a lateral stripe that is broken into spots, a tail spot, and a line above the prolegs.

Photo: Mathew Zappa (iNaturalist)