The Diprionidae are known as the conifer sawflies, though they are not the only family to use conifer trees as hosts (others include Siricidae, Pamphiliidae, Xyelidae, and some Tenthredinidae). Many are destructive pests as larvae, and their biology has been relatively well-studied. Diprionids have stout bodies and distinctive antennal characteristics that make adults easy to recognize (Furniss and Carolin 1977).
Zadiprion is a fairly uncommon genus that occurs in the western United States and Mexico. Adults are large and stout, usually larger than Neodiprion in their overlapping range. Some species are defoliators of pine trees that can have a significant economic impact (Smith 1988).
A key to world species of Zadiprion is included in Smith et al. 2012.
Diprionidae are most easily recognized by the distinctive antennae of both sexes and are characterized by small, stout bodies. Zadiprion can be separated from other genera in the family by the unique partially bipectinate antennae and the tarsal pulvilli (Goulet 1992, Smith et al. 2012).
Larvae in North America feed on several species of pine, including Pinus ponderosa (ponderosa pine), P. monophylla (single-leaf pinyon), P. edulis (Colorado pinyon), P. pseudostrobus (smooth-bark Mexican pine), P. chiapensis (Chiapas pine), P. montezumae (Montezuma pine), P. devoniana, P. maximinoi (thin-leaf pine), P. oocarpa (egg-cone pine), P. leiophylla (Chihuahua pine), P. cembroides (Mexican pinyon), P. ayacahuite (Mexican white pine), P. pringlei (Pringle’s pine), P. durangensis (Durango pine), P. arizonica (Arizona pine), P. herrere (Herrera’s pine), and P. hartwegii (Hartweg’s pine) (Smith 1971b, Smith 1988, Smith et al. 2012).
Unlike the majority of sawflies, some species of Zadiprion do not undergo diapause in winter and instead actively feed as larvae from September to May when temperatures are above freezing. When it is colder, larvae huddle and temporarily cease feeding. The majority of feeding occurs in the spring. Mature larvae are large, up to 40 mm in length, and are varied in coloration. At the end of the larval stage in early summer, they fall to the ground to spin cocoons and pupate. This genus is generally univoltine (Smith et al. 2012).
Zadiprion have been known to severely defoliate trees. Larvae feed on old growth needles, making them similar in habit to Neodiprion. However, fewer outbreaks are recorded for Zadiprion, and it generally has not been as damaging a pest as Neodiprion (Furniss and Carolin 1977).
North America: The range of Zadiprion extends from the western United States east to South Dakota, and through Mexico as far south as Guatemala (Smith 1988).
Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Zadiprion
Details about data used for maps can be found here.