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Three-Lined Lema Beetle

Lema trivittata

Three-Lined Lema Beetle, Tomatillo Leaf Beetle

A close up image of a Lema trivittata three-lined lema beetle against a white background
Photo by Jesse Rorabaugh (CC0)
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Lema trivittata is a leaf beetle targeting the foliage of tomatillo, potato and Chinese lantern. They will only attack the foliage of plants, leaving behind unattractive irregular sized holes. Larger infestations may result in the leaves being completely stripped. The larvae cover themselves in faeces, which can trick some predators into thinking they're just some bird poo. This helps them remain undetected by predators, and sometimes gardeners, too! It's recommended to regularly monitor the leaves of plants to keep damage at a minimum.
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Traits

Will defoliate tomatillo and potato plants.
Damage is rarely severe.

Appearance

Adults: They look similar to the 3-Lined Potato Beetle or the Striped Cucumber Beetle. These beetles are pale yellow and cream, with three black stripes- the stripes are more narrow when compared to the 3-Lined Potato Beetle. They possess 2 black dots on the thorax (pronotum). The femurs, antennae and feet are also black. Larvae: Black-headed, green-grey grubs. They cover themselves in excrement to stay concealed from birds, so they can sometimes go unnoticed by gardeners. Pupae: Unavailable. Eggs: Tiny, yellow and sausage-shaped. The females lay their eggs in clusters beneath the larval food plant.

Symptoms

They will leave holes in tree leaves following feeding. In large numbers, these beetles may deplete a whole leaf. You may find slimy, grey-brown grubs beneath leaves of tomatillo. They leave unattractive, irregular-sized holes in leaves.

Activity

Diurnal

Personality

Order

Coleoptera

Family

Chrysomelidae

Metamorphosis

Complete

Distribution

West of Mississippi

Biological treatment

Picking these beetles of plants as and when they're seen is probably one of the best modes of action. Regularly inspecting leaves for bright yellow eggs and removing them as and when will help to prevent large outbreaks. It's thought that trenches dug between rows of potato plants can capture adults travelling between crops. Slopes should be steeper than 45 degrees and lining them with plastic will make surfaces more slippery. Another tip for reducing beetle movement between plants would be to mulch 5-7cm of straw or hay as soon as plants sprout. Using some polyester sheets as a barrier during spring would add an additional layer of protection against adults in the springtime. Diatomaceous earth is non-toxic, yet acts as a barrier against things such as beetles, caterpillars and slugs. Take care during the application, be sure the eyes are protected and none is inhaled. If available, beneficial nematodes can be watered into the soil. These will eradicate all the grubs in the area covered, including beneficial larvae too.

Chemical treatment

If you have exhausted all the biological options, then you can try to spot-treat plants with organic pyrethrums. Organic pesticides are thought to be more environmentally benign than synthetic insecticides. These contain pyrethrums, fatty oils and plant essential oils. If the infestation is considered most severe, you might want to try synthetic pyrethroids. They are more aggressive in their mode of action but can be applied to plants less frequently. They're also unselective, so will most likely kill any insect that comes into contact with it.

Attracts

Tomatillo

Physalis philadelphica

A close up of a white and yellow Solanum tuberosum flower

Potato

Solanum tuberosum

Flowering Maple

Abutilon spp.

Repels

Larvae are predated by hoverflies, wasps, spiders, and various predatory arthropods.
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