Control. Avoid wounds; prune out infected branches, working only in
dry weather, and sterilize tools between cuts. Fertilize to renew vigor.
Spraying lower branches of spruce 2 or 3 times in spring with bordeaux
mixture or a fixed copper may reduce infection.
Caterpillars are the wormlike larvae of moths and butterflies. They have
chewing mouthparts and soft, cylindrical, smooth or hairy bodies. They
have one pair of jointed legs on each of the first 3 body segments and
short, fleshy, unjointed prolegs on other segments. True caterpillars have
no more than 5 pairs of prolegs (thus differing from sawfly larvae which
have 7), and these prolegs have little hooks or crotches which help in
clinging to a leaf or twig. There is complete metamorphosis. Caterpillars
pupating in a silken cocoon change into moths, those with a naked chrysalid become butterflies.
are small caterpillars that winter in silken cases in twigs
near buds and in spring web terminal foliage together. The SPRUCE
BUDWORM (Choristoneura fumijerana) is the nation's top-ranking forest
enemy and comes next to the cotton-boll weevil and corn earworm in a
list of destructive insects in general. It is also troublesome to spruce, fir,
larch, hemlock, and pine in ornamental plantings in northern United
States. The caterpillar is an inch long when grown, brown, covered with
yellow tubercles. It bores into opening buds and cuts off and webs needles
together. Tops of trees appear as if scorched by fire; heavily infested
Control. In forests, airplane dusting with DDT at the rate of 1 pound
per acre has controlled the spruce budworm without bird mortality. Birds
themselves are helpful, credited with eating ioo to 300 caterpillars per
tree. Spray ornamentals with DDT just after buds break, using 2 pounds
50% wettable per 100 gallons of water.
Other species of budworms or budmoths bore into apple buds or rose
buds, feed on flowers and seed capsules of verbena, snapdragon, iris, etc.,
but can be controlled with DDT or lead arsenate. One small greenish
caterpillar with a shiny dark head ties together terminal leaves of hydrangea over the flower bud into a little pocketbook. It is sometimes pos-
sible to tear this open and kill the budworm with your fingers before it
ruins the flower bud.
inch worms, measuring worms, periodically defoliate
fruit and shade trees, especially oaks and elms, through much of
the country. They are commonly destructive in the East and considered
more damaging to shade trees in the Middle West than any other insect.