Native to the United States, the hawthorn lace bug (Corythucha cydoniae) was first recognized as a serious pest in the middle 1800's.  It is found throughout the United States. 

The hawthorn lace bug lives on the under side of the leaves and sucks out the fluid causing injury to foliage including yellow to whitish speckling on the upper leaf surface decreasing the plant’s aesthetics.  Heavy feeding can cause severe plant stress including large blistered areas, complete yellowing of leaves, wilting, and even death

Susceptible Hosts
* The hawthorn lace bug feeds on a number of plants in the rose family including:  Hawthorn (Crataegus spp.), firethorn (Pyracantha coccinea), apple (Malus spp.), mountain ash (Sorbus spp.), serviceberry (Amelanchier spp.), button bush (Cephalanthus occidentalis), cotoneaster (Cotoneaster spp.), loquat (Eriobotrya japonica), oak (Quercus spp.), and quince (Cydonia spp.)

Pest
Corythucha cydoniae

Symptoms
* Yellow or whitish speckling is visible on the upper leaf surface.
* Heavy feeding can lead to large blistered areas, complete yellowing of leaves, wilting, and early leaf drop.

Signs
* Field identification of adults can be difficult because of several similar species.
* Deposits of hard, dark, varnish-like spots of excrement may be found on the leaf surface, especially along the leaf veins where the female inserts her eggs.
* Adult hawthorn lace bugs are rectangular in shape about 1/8 inch (3mm) long and 1/16 inch (1.5 to 2mm) wide.
* The adult’s wings are lace-like with large, brown areas.  The antennae and legs are yellowish.

Life Cycle
* Adults become active in the spring as leaves appear on the host plant.
* Eggs are laid in groups of 10 to 30 on the underside of leaves along the veins among their pubescence.
* There are five instars before becoming adults, which takes about 30 days.
* Only one generation per year
* Adults over winter under leaves, stones, and in bark crevices.

Distinguish from Look-alikes
Similar speckling is caused by mites, which feed on the upper surface primarily; Mite damage, however, does not stain the lower leaf surface.

Adults become active in early spring as leaves appear on the host plant.  Females move to the leaves to lay hundreds of eggs.  The eggs hatch in approximately 14 days and nymphs emerge. Soil applications of Xytect or Transtect are the recommended products of choice.  Apply Xytect in late summer/early fall for next year control or apply Transtect in early spring for high levels of control. Arborists should only use foliar sprays for immediate activity against the insect.                

Xytect can be applied in late summer/early fall of the previous year to kill larvae.
Transtect can be applied to the soil in early spring.
Foliar sprays  must be timed to control hatching nymphs in the spring of the year.  Repeated applications may be needed to control nymphs that hatch later than the first round of sprays. Ensure that the underside of the leaf is sprayed.             

Expectations:

* Xytect and Transtect will provide a high level of control vs. lacebugs and are the recommended products of choice.
* Insecticides will not restore an undamaged appearance, but can reduce or prevent further damage.
* Almost any insecticide will control lace bugs if it is sprayed directly on to the insect. Foliar spray applications must be made to the underside of the leaf, which can be challenging. 

Other Treatment Practices
* Promote health and vigor with proper irrigation, mulching, proper pruning and prescription based fertilization practices.
* Plant lace bug susceptible host plants in areas of the landscape that are shady, as bright, sunny areas seem to be preferred.
* A hard jet of water from a garden hose can dislodge the young nymphs after hatching in the spring.

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