Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 226

Family PHYLLOCNISTIDAE

Phyllocnistis unipunctella (Stephens) ( 545-547 )
syn. P. suffusella (Zeller)
larva A small family of very small moths with an 'eye-cap'.

The larvae are apodous, sap-feeding leaf miners.

poplar leaf miner
An often abundant leaf miner on black poplar ( Populus
nigra ) and Lombardy poplar ( P. nigra 'Italica'),
including trees growing in gardens and nurseries.
Although present throughout much of mainland Europe,
in Britain it is found mainly in England and south-east
Wales. Adults occur in July and from September to April,
those of the second generation hibernating and
eventually depositing eggs in the spring. The larvae feed
in June and in August, each forming a very long, slightly
raised but inconspicuous, gallery on the upper side of the
leaves. The mines are most obvious when a leaf is
viewed at an angle; they then appear as silvery, slug-like
trails. The larvae (up to 5 mm long) are pale greenish
white, with a transparent head and a blackish prothoracic
plate; unlike members of the Gracillariidae they are sap
feeders throughout their development, excreting a clear
liquid instead of faecal pellets. Fully grown larvae
pupate in whitish cocoons, each usually spun externally
under a fold of the leaf margin at the end of the larval
gallery. The adults (7-8 mm wingspan) are superficially
similar in appearance to those of various species of
Phyllonorycter (p. 228-233). Damage caused by this
insect is unimportant and usually noticed only when
foliage of trees is examined closely for other disorders;
however, in some situations mined leaves are reduced in
size, suggesting that persistent attacks on young hosts
might have an adverse effect on tree growth.

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Phyllocnistis citrella (Stainton) ( 544 )
Citrus leaf miner moth
In recent years this Asiatic leaf-mining species has
become well established as a pest in citrus-fruit
orchards in southern Europe. Citrus plants being raised
as ornamentals are also attacked. The mines are very
long and sinuous, and occur on either side of the leaves.
Occasionally, young shoots are also attacked. Heavy
infestations lead to premature leaf fall and dieback of
shoots. Adults (5-8 mm wingspan) are mainly white;
the fore wings are partly suffused with yellowish
orange, and marked with black striae and a black pre-
apical spot. Larvae (up to 3.5 mm long) are translucent
and partly yellowish. The pest overwinters as adults,
and under suitable conditions completes several
generations annually.

544

544 Mine of citrus leaf miner moth ( Phyllocnistis citrella )
on Citrus .

546

545

545 Mines of poplar leaf miner ( Phyllocnistis unipunctella )
on Populus .

546 Poplar leaf miner ( Phyllocnistis unipunctella ).