Then they emerge and construct tiny cases in which they migrate 
to the twigs where they spend the winter. Feeding is resumed in 
the spring with each larva eating out a tiny circular hole in a 
leaf and then, without leaving its case, mining out an area be- 
tween the larger veins as far as it can reach. The case is en- 
larged as needed to accommodate the growing larva, eventually 
reaching a length of 9 to 10 mm. This species is primarily a pest 
of shade and ornamental trees. The mined parts of laves turn 
brown and, where numerous, are unattractive. Fortunately, out- 
breaks are usually limited. 
The larch casebearer, Coleophora laricella (Hbn)., an intro- 
duced species, was first recorded in North America in Massachu- 
setts in 1886. It now occurs throughout most of the range of 
tamarack, Larix laricina, in North America, west to central 
Minnesota and northwestern Ontario. In 1957, an infestation was 
also discovered on western larch, L. occidentalis, in Idaho (191). 
The adult is silvery to grayish-brown, has narrow wings fringed 
with long hairs, and a wingspread of about 9 mm. Full-grown 
larvae are about 6 mm. long. The pupa is colored brown. This 
species is one of the most serious defoliators of larch in North 
America. Outbreaks have been occurring at about 8 year inter- 
vals in eastern Canada. One was also recorded in the Lake States 
in the late 1940’s and early 1950’s. Heaviest losses result from 
reduced growth. Trees completely defoliated for 2 or more years 
in a row may be killed. | 
Eggs are deposited singly on needles in early summer and hatch 
in about 2 weeks. The newly-hatched larva bores directly into a 
needle and continues to mine it until late summer. Then the 
larva lines a hollowed section of the needle with silk and chews 
the section free at both ends. thereby forming a case. The re- 
maining larval period is spent in the case, which is enlarged as 
needed. A single larva may mine several needles before the 
needles fall. Before the onset of cold winter weather, the larva 
migrates to an outer twig or branch to which it fastens its case, 
usually at the base of a bud. Several cases may be found grouped 
together around the bases of spurs from which new needles arise 
in the spring. The most serious damage is done by the large larvae _ 
as they feed on newly developing foliage during the spring. 
Adults emerge from late May to early July, depending on locality 
and season. There is one generation per year. 
The larch casebearer is attacked by more than 50 species of 
native parasites in eastern America, but none are particularly 
effective in control. Two introduced hymenopterous parasites, 
Agathis pumilus (Ratz.) and E'pilampsis laricinellae (Ratz.) are 
now widely distributed and are believed to be quite helpful in 
control. 
The birch casebearer, Coleophora fuscedinella (Zell.) (=salmant 
Heinr), an introduced species first observed in North America 
in Maine in 1927, is now known to occur throughout the North- 
eastern States and from Newfoundland and New Brunswick to 
southern Ontario, Canada. Its favored hosts are paper, gray, and 
European white birches. Eggs are laid along the mid-ribs and 
larger veins on the undersides of leaves in July. Young larvae 
enter the leaves and feed as miners for several days; then they 
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