Other Common Names
Diprion importé du pin (French)
Synonyms and other taxonomic changes
Diprion simile is a misspelling based on the assumption that Diprion is grammatically neuter (it's masculine)
Range
Every US state east of the Mississippi River from Tennessee and North Carolina north, as well as Minnesota.
In Canada, from Newfoundland south to New Brunswick and Nova Scotia, then west through Quebec and Ontario to Manitoba. Apparently also in British Columbia, Canada and Washington state in the US.
As with any introduced species, range extension is to be expected.
Season
Adults can be found throughout the season, from first emergence in mid-spring to
pupation in mid-fall (in favorable weather they may stay active even longer). Late-emergers and two generations mean all stages of development can be found together at the same time.
Food
Pine trees (Pinus) are the only host. 5-needled pines (Subgenus Strobus) are preferred, but some others are infested as well. Some of the species:
Subgenus Strobus: Swiss Pine (P. cembra), Limber Pine (Pinus flexilis),Western White Pine (P. monticola), White Pine (P. strobus)
Subgenus Pinus: Jack Pine (P. banksiana), Mugho Pine (P. mugo), Red Pine (P. resinosa), Pitch Pine (P. rigida), Scots Pine (P. sylvestris), Loblolly Pine (P. taeda), Virginia Pine (P. virginiana)
Life Cycle
Male:
Female:
Adults emerge as early as April, depending on the climate, and mate (Females that fail to mate can still lay eggs, which hatch to produce males). The females make slits in needles with their
ovipositors to lay their eggs- about 10 per needle. When they first emerge, the larvae feed in groups, but spread out as they get older.
Larva:
There are often two generations, with the first spinning cocoons in early July, emerging in early August, and laying eggs which hatch into the second generation. The second generation generally spins cocoons in September in the litter under the trees.
Most go into
diapause in a pre-pupal state until spring, then pupate. Some may not emerge with the others, remaining in diapause until later in the season, or even for 1-3 years.
Empty Cocoon:
Remarks
Introduced from Europe: first reported in North America in 1914, in Connecticut. Although a serious pest at times, it normally stunts rather than kills its hosts. It can be a more serious problem with young trees and in cases such as Christmas trees where appearance is important. It has natural enemies and diseases, so large outbreaks are only intermittently seen.
