Lily Pests

Lily Beetle

Sooner or later if your growing lilies you are going to run into this little pest. The Lily Beetle (Lilioceris lilii) is probably the most serious pest of lilies world wide. It came over to North America from Europe around 1992. Now it is in Eastern Canada and has recently been reported in Manitoba.

Both the scarlet red beetle and the larvae feed on the foliage and can strip a plant bear very quickly. The adult beetle is a bright scarlet red, measure about .2 inches and have black legs. The larvae look like orange slugs and are found underneath the leaf they are feeding on. They have the habit putting their own excrement onto their backs so look like a black drop of goop. The do not actually kill the plant but because the strip off the foliage the lily cannot make any food for storage in the bulb. This weakens the bulb, if the attacks continue year after year the plant will finally perish.

The females lay their eggs on the underside of the leaf and they look like tiny orange elongated dots. When they hatch the larvae feed for about 16-24 days. The adults will emerge after 16-22 days of pupation and start the process over again. There can be multiple generations in a season. In the fall the adults like to hibernate near the ground. I quite often find them in the crown of Hemerocallis or Daylilies, also in Rudbeckia and Echinacea clumps.

In North America they do not have any natural predators. However once I noticed on one of my lilies a Japanese Lady Bug that seemed to be feeding on the eggs. The Japanese Lady Bug is a new arrival to North America and was causing quite a stir a couple of years ago. They are more aggressive that the native Lady Bug and are starting to compete for food. The North American Lily Society is actively researching a non chemical way to control the beetle. There is a predatory wasp that attacks the beetle and is showing great promise. Neem Oil is being sold by garden centers as a control but check with your local garden centers as to its availability. If you have a large infestation spraying might be necessary, but collecting the beetle and killing by hand is sufficient if you have a small problem and do not wish to use chemicals. I personally do the "Bug Run" daily in the morning and again in the evening to control the problem. Not sure what nature was thinking when she made a bright red beetle that stays on green plants. Its not to hard to spot the adults. But be warned they have a tendency to just drop from the plant when they sense your presence. You can place a collecting bottle or your hand under the leaf to catch them should they drop. The larvae are a little harder to spot as they are always under the leaves. Look for damage to the foliage it is usually a sure indication of lily beetle larvae feeding. Remember they are covered in excrement so using your hands to remove them is not the most pleasant thing to do. Wear tight gloves or a rag to collect them.

The lily beetle will attack related plants genus such as Fritillaria, they however do not bother with Hemerocallis.

Aphids

Aphids are an important pest not only to lilies but to most other plants as well. Aphids left uncontrolled could pile up on the Earth a yard deep in one season from one female. There is only one male generation per year usually in August you find winged aphids and this is the mating generation. The males and females mate and then the males die. The female will lay eggs in cooler climates until the following spring. The eggs will then hatch. When the aphids are mature they will start toreproduce live baby aphids. All the babies are female and within their body are the next generation of females who have the next in their body and so on. This form of reproduction is called Parthenogenesis. So control of Aphids is a must at all cost.

Aphids are sap sucking insect that slowly and drain the liquids from a plant. They are also the main cause of viral transmission, by feeding off of a diseased plant and moving onto a healthy one.

If you have a small number of plants and the infestation is minor you can try killing them by hand or using jets of water from a garden hose. Lady Bugs and their larvae are voracious killers of aphids, so are spiders. So if you can find lady bugs and spiders you may want to move them to a colony of aphids and let them feast.

If your infestation or garden is to big for spot control you may have to resort to chemical means to control them. A systemic pesticide is watered into the soil and the plants take them up. When the aphids begin to suck onto the plant the poison is ingested at the same time killing them. Systemic pesticides is a very good way for control in container gardening.

If you're going to use chemicals be sure to read the instructions and take all possible precautions when apply it not to get into your eyes or into your lungs. There is a reason professionals use protective clothing and respirators when applying pesticides.

Organic non-pesticide control is always the best if your infestation is not to large. Try planting aphid resistant plants, clean up any dead leaves that may over winter aphid eggs. Bark mulch is also a potential place for over wintering pest insects. Look for predatory insects to do what nature intended them to do. Lady Bugs can be bought for release into gardens as well as Mantis eggs. Try insecticidal soaps before using commercial insecticides.

Here are a couple of organic spray recipes:

1 lb (0.5 kg) of rhubarb leaves
2.5 pt (1.5 l) of water
Simmer leaves in water for 30 minutes
Strain the mixture and store in a glass jar - when ready to use
add 1 fl Oz (28ml) of dishwashing liquid in 2.5 pt (1.5l) of water and mix
with the Rhubarb extract

or

3-4 hot peppers
a few cloves of garlic
1 quart of water.
Mix it all in the blender, then spray on plants.

The internet is a great place to find more organic controls.

Slugs

Most people who garden have seen the slimy trails of slugs before. Slugs are basically large shell-less snails. They can cause allot of damage feeding on the new spring shoots. There for it is important to control slugs. Traps or pellets can be placed out to catch them, but make sure that they are pet safe. Beer traps are excellent for trapping and drowning slugs. just pour some beer into a shallow container and place it close to your lilies.

Slug eggs can be controlled by cultivating the soils top few inches or so. This will expose them to birds and frost. Control weeds in your garden, as this reduces potential habitats for then.

These are a few of the main diseases and pests to look out for in your garden. Others can be found on the internet or in Lily specific reference books.