Use lindane emulsion according to directions on
the bottle or wettable powder at the rate of 1 pound of 25% wettable to
100 gallons of water. Or use chlordane at rate of 5 pounds 40% to 100
gallons. Summer sprays with dieldrin and aldrin will kill miners inside
BOXWOOD LEAF MINER (Monarthropalpus buxi).
This fly is our most
serious boxwood pest. Infested bushes often have every leaf blistered
(Figure 32A) and look decidedly unthrifty, dying little by little. Inside
each blotch or blister one to several small yellow to orange wriggling
maggots live through the winter. Near the first of May (in New Jersey)
they quiet down, acquire dark heads, and little opaque windows are
formed over the blisters on underside of the leaves. Pupa cases are then
pushed through these windows, and small orange flies emerge to lay
eggs. Emergence varies according to the season and location. The earliest
date I have recorded in my practice is May 8th, the latest May 20th;
the average is May 14th. Further south emergence would be a week
or two earlier. The flies are present for only 10 to 14 days, and there is
only one generation.
Control. We used to rely on a sticky molasses and nicotine concoction,
putting it on again after every rain and never getting much result. DDT
now gives really spectacular control. One application, properly timed,
of 2 tablespoons 50% wettable DDT per gallon, is effective, but it must
be in place before the flies come out. They start egg-laying the same day.
If cool weather delays emergence a week or more after expected, a second
application of DDT may be desirable. Early summer spraying with
lindane will kill young larvae in new leaves.
COLUMBINE LEAF MINER (Phytomyza minusculd).
striking white winding tunnels, are seen in nearly every clump
of columbine. Dark flies emerge from the soil in May and June and lay
eggs on underside of leaves. Pale maggots feed for about 2 weeks, then
form brown puparia on the leaves, with adults appearing in another
fortnight. There are several generations a season with pupation of the
last brood in the soil.
Control. Spading the ground around the clumps in spring destroys
many overwintering pupae. Spray or dust foliage with DDT.
HOLLY LEAF MINER (Phytomyza ilicis)
a European insect common on
American holly, sometimes on other kinds of Ilex. The pale-yellow
maggot, 1/8 inch long, makes a yellow-green blotch mine visible on the
upper leaf surface. It stays in the mine over winter, emerging as a small
black fly in late May or when there are 2 or 3 new leaves on the terminal