Loblolly and shortleaf pines are the only trees attacked by the Arkansas
pine sawfly. Periodic outbreaks of this insect over large areas in the
south-central states cause substantial growth losses, but the insects
seldom kill trees.
[Illustration: Arkansas pine sawfly larvae.]
This insect has a single generation each year. In the spring, eggs which
have overwintered hatch into tiny caterpillar-like larvae. The larvae
feed in groups for 30-40 days (primarily on the older foliage) before
crawling to the ground and pupating in the topsoil or litter. Adults
emerge during warm days in October and November, mate, and the females
begin laying eggs. Sawflies get their name from the manner in which the
eggs are laid. The female is equipped with a saw-like “ovipositor” with
which she cuts a slit in the needle into which the egg is inserted. From
two to ten eggs are laid in a single needle. Each female deposits from
90 to 120 eggs.
An important natural control agent of this sawfly is a polyhedral virus
disease that sometimes destroys large numbers of the larvae. Rodents
destroy many cocoons. Several species of larval parasites are also known
to exist. Of these, a parasitic fly, _Anthrax sinuosa_ (Wied.) and an
ichneumon wasp, _Exenterus canadensis_ (Prov.) appear to be the most
important.