Minnesota, Illinois, Missouri, and south to Louisiana. Full-grown larvae are shiny 
green and about 12 mm long. Adults appear to be most numerous in October. Eggs 
are laid in slits cut in the lower surface of the leaf. They are placed singly in rows 
along the sides of the midribs and larger veins, and all hatch within a few days after 
being laid. The larvae feed on the epidermis of the leaf, leaving it almost colorless 
and transparent. Evidence of feeding is apparent during late summer. There may be 
two generations per year, and the winter may be spent in the larval stage (74). 
Caliroa petiolata Smith occurs on pin oak in New Jersey. Three other species of 
Caliroa are known on oaks, one on tupelo, one on chestnut, and one on Prunus spp. 
The genus Periclista is represented in eastern forests by 10 species that feed on 
the leaves of oaks and hickories. The larvae are usually light green or have the 
dorsum grayish, and are armed with rows of small, single spines that may be simple 
or forked. 
The larch sawfly, Pristiphora erichsonii (Hartig), was first recorded in North 
America in 1880. It now occurs in all Canadian Provinces, in Alaska, and all of the 
northern tier of States plus Maryland, North Carolina, and West Virginia. Its hosts 
are listed as tamarack and Western, subalpine, European, Japanese, Dahurian, and 
Siberian larches. In eastern America, tamarack is most seriously infested, but 
planted exotic larches are coming under increasingly serious attack. Full-grown 
larvae are whitish beneath and gray-green along the dorsum, have jet-black heads, 
and are about 16 mm long. Female adults are black and from 6 to 9 mm long. The 
abdomen has a broad orange or red band, tapers sharply posteriorly, and is keeled 
longitudinally along the midventral line. 
In the Lake States, winter is spent in the prepupal stage in the ground. Pupation 
occurs in the spring and the adults appear from mid-May to August, depending on 
temperature and location. Eggs are laid in rows under the bark of currently 
elongating shoots on the branches, and hatching occurs in about 8 days. The 
emerged larvae move to and feed in groups upon tufts of needles, which are found 
on short shoots on the older twigs. Feeding is completed in about 20 days and 
mature larvae drop to the ground, enter the duff, and spin papery, brown cocoons. 
Because of the long period of adult emergence, feeding larvae, cocooned larvae, 
pupae, adults, and eggs all may be found at the same time in early summer (fig. 
192). There is one generation per year, but occasionally small numbers of second- 
generation adults are produced too late for any larvae to complete feeding. A small 
number of larvae enter diapause and require 2 years to complete one generation 
(332, 496). 
Because larvae have the feeding behavior of rejecting single needles found on 
elongating shoots in favor of needle tufts found on short shoots, 100 percent 
defoliation seldom occurs. The chemical basis for this differential feeding appears 
to be the presence of relatively high concentrations of five deterrent chemicals in 
single needles from mid-July into August (945). Heavily defoliated trees commonly 
refoliate after a few weeks; however, repeated defoliations can result in trees with 
thinned foliage, reduced radial and terminal growth, reduced production of normal 
shoots with a tendency toward adventitious growth, and branch mortality. Marked 
loss of radial increment occurs after 4 to 6 years of outbreak, and tree mortality 
occurs after 6 to 9 years of moderate to heavy defoliation. Many widespread 
outbreaks have been recorded since 1880 and losses have been severe. Since the 
middle of the 1950's, an estimated volume loss of 40 percent in valuable sawtimber 
and pulp stands has occurred in managed forests in Minnesota. 
402 
