LIBRARY

764 COLLEGE ENTOMOLOGY
(1) Free-living larvlE which feed in the stems, flowers, fruit, and other parts
of the plants. The most important species is the Hessian fly, Phytophaga
destructor (Say), which originated in Asia and was introduced with hay or
cereals into Europe and eventually into North America by the Hessian soldiers
during the Revolutionary War about 1779. It reached the Pacific coast previous
to 1881-. As a pest of wheat it has few contenders and has been especially
destructive in the northern United States and southern Canada east of the
Rocky Mountains. The larVa! live and feed on the stems beneath the leaf
sheaths and kill the plants. It has two or three generations a year. The
pear midge, Contarinia pyrivora Riley, which oviposits in the flowers of pear
trees and whose larvre develop in the young fmit in North America and Europe,
is a serious pest in many localities, as are also other similar species on grapes.
C. gossypii Felt, the cotton flower lint maggot, is important in the West Indies.
(2) Leaf-rolling larvre like Dasineura rosarum Hardy (Dasyneura) on peach
and D. pyri Bouche on pear in Europe, the violet midge, Contarinia violicola
(Coquillett), on violet in eastern United States, and many species on wild
plants.
(3) Inquilines in the galls of other insects as Phmnolauthia cardui Kieffer
which inhabits the galls of a trypetid fly on thistles in Europe.
(4) The gall makers which produce galls of various shapes and sizes in the
flowers and on the leaves, stems, and roots of many plants, but which particularly
infest the species of the plant families GRAMINE.tE, SALICACE)E, and
COMPOS IT .tE.
Some other rather important economic species are: The chrysanthemum gall
fly, Diarthronomyia hypogaJa (F. Low), which produces small galls in the
flower heads and leaves of cultivated chrysanthemums. The sorghum midge,
Contarinia sorgkicola (Coquillett), which feeds on the seeds of sorghum in
southern United States. The wheat midge, Thecodiplosis mosellana Gehin
(== tritici Kirby), a pest of wheat in Europe and North America. The rice
midge, Packydiplosis oryz.:e Wood Mason, a very sedous pest of rice in Indo­
China and Japan. The clover flower midge, Dasineura leguminicola (Lintner),
the larvre of Which destroy the flowers and seeds of clovers in parts of western
Europe and North America.
Pupation takes place in single or double cocoons or in a puparium in the galls
of the host or other habitat of the larva or in the soil.
The members of the very interesting genus Miastor Meinert which are widely
distributed have been the object of much study because of the phenomenon of
predogenesis in the metamorphosis of the species M. metralos Meinert of
Europe and M. americana Felt of North America. At certain times four or five
large eggs develop in the females which hatch into large larvre. These consume
the body of the mother, and very shortly each gives birth to from seven to 30
daughter larvre which may in turn produce several successive generations of
larvre. At intervals in this succession some larV1e pupate and develop into
mature sexes which mate and repeat the process. A similar phenomenon also
occurs in the genus Oligarces Meinert of Europe (Imms, 1934),