| | 42. Leafminers are a diverse group of insects which includes
some flies, beetles, moths, and sawflies. |
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43. Leafminers live and feed between the upper and lower leaf
surfaces. The shape of their mines is often characteristic and
helps to identify the pest. This is the holly leafminer. The
insect that causes the damage is the larva of a tiny fly. |
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44. The boxwood leafminer is also a delicate fly. Adult
females, like this one, insert their eggs through the epidermis
of new leaves. |
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45. After hatching, the maggots feed within the leaves, causing
unsightly blisters to appear. |
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46. It is not uncommon to find half a dozen maggots per leaf.
Though infested plants are rarely killed, they become sickly and
unappealing. A systemic insecticide, one that is absorbed into
the plant, is necessary for effective control. |
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47. These winding tunnels indicate the presence of columbine
leafminer. This tiny leafminer maggot seems to wander as it
feeds. |
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48. The adult locust leafminer is a small yellow and black
beetle. |
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49. The mines of their larvae seen here on the right are
sometimes responsible for turning entire black locust trees brown
in mid-summer. The adults are pests as well. Their feeding
damage to black locust is pictured here on the left, but many
plants including dogwood, elm, oak, and apple may also experience
some damage. |
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50. Yellow or brown tips on arborvitae indicate the presence of
a small leafmining moth known as the arborvitae leafminer. |
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51. Arborvitae leafminer caterpillars are only 1/5 inch long
when full grown.
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52. They are so small that they can feed and complete their
development inside the narrow arborvitae leaves. Infestations of
this and many other leafminers can be controlled most effectively
with a systemic insecticide. |