Stephanitis pyrioides (azalea lace bug)

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Stephanitis pyrioides        Family: Tingidae

Common name: azalea lace bug
Host plant: azalea; rhododendron

Adult size: 2.5 mm (0.1 inch)

Type: Pest

Life cycle: Generations per year: two to four
                    Egg: 12 – 22 days
                    Nymph: 10 – 23 days through 5 instars
                    Adult: 1 – 4 months

Description & life cycle: Adult lace bugs are roughly 2.5 mm (0.1 in) long. Their cream-coloured body is slightly flat and elongated. The clear wings are laced throughout with tan-brown veins and they lay neatly folded and flat over the abdomen, extending just over the extremities. Given their colour and clear wings, these adult lace bugs can be rather difficult to spot with the naked eye on an infested shrub. Adult longevity is variable; one to four months within a temperature range of 20.5 °C (69 °F) and 32 °C (89.5 °F).

Each day, a female lace bug pierces the lower epidermis layer along the leaf midrib or margin in which to lay 5 – 7 eggs. She then covers them with a brown secretion which hardens to protect the eggs from damage and predators. Over their lifetime, females can lay about 300 eggs, or more.

The white eggs are tiny at a mere 0.36 – 0.43 mm (0.014 – 0.017 in) long and 0.16 – 0.23 mm (0.006 – 0.009 in) wide. They are oval-shaped with a slightly curled neck, resembling a tiny flask. The egg incubation period generally lasts for about 22 days when temperatures hover around 20.5 °C (69 °F); shorter at about 12 days when temperatures rise to around 32 °C (89 °F).

The young nymphs stay together and feed near the egg remnants for the first couple of instar stages before seeking out other feeding spots as they develop through the remaining three instars. They are very pale in their initial instar stages, gradually darkening to dark brown or black and forming spines around the lateral edge of their body. Nymphs are extremely minute at 0.1 mm (0.004 in) in their first instar to 1.8 mm (0.07 in) in their fifth instar. Nymph stage lasts for about 11 days at 32 °C (89 °F), up to 23 days at 20.5 °C (69 °F).

Special Notes: Native to Japan, the azalea lace bug has spread quite widely through the global movement of its very popular, and desirable, host plant. It was positively identified in New Jersey as early as 1915, and more recently in Washington State in 2008 and Oregon in 2009.

The young lace bugs develop on the underside of the leaves, inserting their stylet into the stomata and sucking the sap from the inner leaf tissue. As their population increases, the effects of this feeding results in a yellow mottled appearance on the upper side of the leaves.

Azalea lace bugs feed on both evergreen and deciduous azaleas and rhododendrons. Large populations of this pest can cause serious stress to the plant, even causing death.

Typically, lace bug populations are higher on plants situated in a sunny location versus a plant in a shadier area.

Remedial actions: Spray the upper- and undersides of the leaves with horticultural oil during the winter. This is to minimize killing any beneficial insects which may be nearby, feasting on the lace bugs. Beneficial insects include: ladybugs, lacewings, earwigs and spiders. Repeat to ensure all eggs have been coated with oil and thoroughly smothered.

Through the growing season, provide adequate water and fertilizer for the benefit of healthier plants which are better able to withstand pest damage. Placing mulch underneath the plant will help to keep the soil moist.

 

Posted on December 3, 2018

Stephanitis takeyai (pieris lace bug)

 

Pieris lace bug - adult

Stephanitis takeyai        Family: Tingidae
Common name: pieris lace bug; andromeda lace bug

Host plant(s): Pieris spp.; Rhododendron spp.
(Found on Lindera benzoin & Sassafras albidum in Washington, D.C. in 1977)

Adult size: 0.08 – 0.2 inch (2.0 – 5.0 mm)

Type: Pest

Stephanitis takeyai now found in areas of the Comox Valley but not in our garden, as yet.

Life cycle: possibly as many as five generations per year, depending on region
                   egg – overwinters
                   nymph – 5 instars, or growth stages, lasting about one month
                   adult – lays about 300 eggs; does not overwinter

pieris lace bug egg

 

Description & life cycle details: Eggs…inserted into, or alongside, the mid-rib on the underside of the leaves and covered by a dark-coloured, varnish-like secretion…overwinter on the underside of pieris leaves. Hatching begins sometime in late April or early May, depending on temperature in your region. Egg hatching can extend over a period of roughly one month.

 

pieris lace bug nymphsEmerging nymphs are relatively clear in colour…beginning to darken within a few days. Initially, the young nymphs will remain clustered together but start spreading out into new feeding territories after the second or third moult. They go through 5 instars, or growth stages…the whole growing and moulting process taking roughly about one month. By the time the nymphs reach the 4th instar, they have darkened to brown-black in colour and have grown spines on their bodies. At 5th instar, nymphs are half the size of an adult lace bug.

Pieris lace bug - adultAdults are up to 0.2 of an inch (5.0 mm) long. Bodies are slightly flattened and black in colour. Clear wings, conspicuous because of the black, lace-like veining and prominent black X-shaped marking, lay flat along the body. Females lay five to seven eggs per day…as many as 300 in their lifespan. There are multiple generations per year, depending on the temperatures and length of the growing season in your region. (Research conducted by the entomolgy department at Pennsylvania State University revealed two to three generations of Stephanitis takeyai occur in that state. The University of Connecticut claims four to five generations are produced every year in their state. No reference found for number of generations in BC.)

Special Notes: Native to Japan, this pest was accidentally introduced into the United States around 1945…according to the University of Connecticut. And yet, reports from England claim the pieris lace bug was not discovered in that country until 1998 when it was spotted in a garden near Windsor. In truth, it is definitely on the move.

Both nymphs and adult lace bugs feed on the underside of Pieris spp. leaves…piercing the epidermis layer and sucking up the plant sap. Early clues this pest may be present are the yellowing and mottled appearance on the upper side of the leaves. This mottling and discolouration impacts on the photosynthesis process…reducing overall plant vigour and causing premature leaf drop.

Of special note, the Entymological Society of Washington reported their discovery of two new host plants for Stephanitis takeyai. This pest was found on Lindera benzoin (spicebush) and Sassafras albidum (sassafras) in parts of D.C. in 1977.

Remedial action: During winter months, check underside of pieris leaves for a line of varnish-like substance along the midrib. This is an indication there are hibernating eggs. Treat with horticultural oil at this stage. Keep an eye on shrubs in late April through into May for any signs of hatching light-coloured nymphs. If spotted, and while they are still in a cluster, spray leaves with either horticultural oil or an insecticidal soap. Best results are treating the nymphs while their body is still soft. It will begin to harden by the third moult or so. Repeat spraying in ten to fourteen days to catch newly hatching nymphs…and continue to monitor the shrub for any further pest activity.

A few beneficial insects have been found feasting on lace bugs: ladybugs, lacewings, earwigs and spiders. Be sure any remedial action you take does not endanger the lives of these beneficial insects as they are worth their weight in gold many times over against this prolific pest.

 

Posted on January 31, 2015; updated on November 26, 2018

Brevicoryne brassicae (cabbage aphid)

Brevicoryne brassicae - cabbage aphid

Brevicoryne brassicae      Family: Aphididae

Common name: cabbage aphid
Host plants: restricted to plants in the Brassicaceae family
(see full list below)
Adult size: wingless = 0.10 inch (2.5 mm)
                        winged = 0.07 inch (1.8 mm)

Type: Pest 

Life cycle: Generations per year: up to 15 during growing season
                       Egg: overwinter
                       Nymph: 7 – 12 days
                       Adult: 30 – 50 days

 

Description: A minute, soft-bodied, sap-sucking insect; elliptical in shape, becoming more round as it matures through the nymph stages. Has six, long, thin legs; two long, six-segmented antennae which are carried over the body; sucking mouthparts called stylets which are enclosed in a sheath called a rostrum; a pair of very short, upright, backward-pointing tubes called cornicles (or siphunculi) located on the 5th or 6th segment of the abdomen; a shorter projection called cauda located above the anal plate. The cabbage aphid is greyish-green in colour.

Aphids have a complicated life cycle. In temperate climates, overwintering eggs hatch in spring.  The first generation of wingless females (called stem mothers) are already pregnant…reproducing by parthenogenesis (without fertilization). The offspring are born live, called viviparity…a unique phenomenon in this insect. Stem mothers continue to reproduce throughout the summer, typically giving birth to 5 or 6 nymphs per day.

When the host plant becomes overcrowded, or its resources reduced, some of the offspring will develop into adults and grow two pairs of large, clear, membranous wings. Once able to fly, these winged adults, called alates, leave the host plant in search of another, fresh plant.

In northern climates, towards the end of the season, the stem mothers produce both male and female offspring. This is timed to dropping temperatures and lowering light levels as the season winds down. After mating, the females lay their eggs in the plant debris of the host plants at soil level, where the eggs will overwinter. (In warmer climates, there is no egg stage in the aphid life cycle. The stem females reproduce continuously throughout the year.) Cabbage aphid eggs are black in colour.

 

Special Notes: Originally native to Europe, the cabbage aphid is now found worldwide.

It is generally thought aphids have been on the planet for roughly 280 million years, placing them in the early Permian period. The oldest aphid fossil was found several years ago in China…an almost complete insect, minus part of the antennae and part of its legs. It has been determined to be a completely new species of aphid and named Dracaphis angustata. The aphid fossil was dated and found to have actually lived during the Middle Triassic Age…after the Permian period.

To explain some of the body parts on the aphid…the cornicles, or siphunculi, those slightly elevated, slender protrusions on the back of an aphid, are defensive apparatuses which will exude a fluid that hardens when it comes in contact with air as a deterrent to predators. The substance is also thought to contain alarm pheromones.

The shorter cauda tube, located above the anal opening, serves to collect the honeydew excreted from the anus and hold it raised so it does not foul the body.

 

Host plant list: Cabbage aphids are a particular pest to cabbage, cauliflower, broccoli, Brussels sprouts, rape, radishes, numerous mustards, and kale.

 

Remedial Actions: There are several predator insects which hunt aphids…lady beetles, ant-lions (green lacewing larvae), yellow jackets, European paper wasps, and others.

Organically…usually a strong jet of water from the hose, repeated every few days, will dislodge these pests. If possible, and if there are no beneficial insects feasting on the aphids, grasping the affected area of branch between two fingers and sliding them up the branch will squish many of the offenders. Same goes for rubbing fingers over infested leaves.

Another plan of attack is to hit the aphids with a soapy water solution…2 teaspoons (10 ml) of dish soap into 4 cups (1 L) of water, but first check to see if there are any beneficial insects present before you start spraying.

Concentrated, repeat forays against this pest are required in order to eradicate them. With the fast turnaround in their reproduction cycle, their numbers can get out of hand very quickly.

 

Posted on November 8, 2018

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