ELM SAWFLY (Cimbex amencana).
Larvae are pale yellow green with a
black stripe down the back, black spiracles, 8 pairs of prolegs, 13/4
inches long. They rest in a coiled position. Eggs are laid in leaf tissues
in May, and larvae feed until late July or August.
EUROPEAN SPRUCE SAWFLY (Diprion hercyniae).
An enemy of north-
eastern spruce forests, this species has reached its peak of abundance
and is now declining from natural causes. Larvae are light green with
narrow white stripes.
IMPORTED CURRANT WORM (Nematus ribesit),
present every season on
currant and gooseberry. Greenish worms with numerous black
spots feed in from leaf margins (Figure 48A) and when numerous entirely strip the foliage. They winter in cocoons in the ground, and black
and yellow adults lay eggs in veins in spring just before leaves are full
size. There is a second, less important, generation in late June or July.
Control. Rotenone dust is easy to apply and safe when currants are
LARCH SAWFLY (Pristiphora erichsonii).
This species appears in epidemics
in the Adirondacks and the Lake States, defoliating trees in forests
and home plantings. The larvae are olive green with black head, legs,
and rows of tubercles, and brownish spines.
PEAR-SLUG (Caliroa cerasi).
On pear, cherry, and plum. Small, dark green
to orange, slimy, sluglike larvae, up to 1/2 inch long, skeletonize
foliage. First brood larvae, hatching from eggs laid on the leaves soon
after trees come into foliage, feed for 2 or 3 weeks then pupate in the
soil. The second brood, working in August, may defoliate young trees.
Control. Pear-slugs are readily killed with lead arsenate, at rate of 2
pounds to 100 gallons, plus 4 ounces of soybean flour.
PIN-OAK SAWFLY (Caliroa lineata).
This can appear in decidedly epidemic proportions as we learned to our sorrow in 1948 in New
Jersey. All the pin oaks turned brown in the upper third or half of the
tree from leaf skeletonization. The larvae look much like pear-slugs.
Control. Either lead arsenate or DDT will control the insect in years
when it promises to be important. This enemy provides another good
argument for diversified planting. We should not have Oak Lanes lined
with the same type of tree ready to succumb all at the same time to a
Several species infest nearly all ornamental pines
at some time during the season.
EUROPEAN PINE SAWFLY (Neodiprion sertijer).
Until control measures
were worked out, this rather recently introduced species played
havoc with pines in New Jersey watersheds as well as ornamental plantings. It is common on mugho and Scotch pine, rare on white pine. Eggs
are laid in slits in the needles and just before hatching, mid-April, resemble pine needle scales