How to Kill Bugs in the Soil of Amaryllis

Soil-dwelling insects, like slugs, wireworms and grubs cause damage to amaryllis plants.

Amaryllis are popular perennial bulbs that thrive in tropical and subtropical conditions. The trumpet-shaped, showy flowers bloom in the spring and early summer, and grow well in pots, greenhouses or garden beds. Amaryllis are susceptible to a few types of insects, some of which hide in the soil, causing the damage to be noticed before the pest.

Things You'll Need

• Copper Strips
• Ground Beetles
• Diatomaceous Earth
• Beneficial Nematodes

Instructions

Determine the Insect

1. Identify the type of soil dwelling insect in the amaryllis's soil. Slugs and snails are soft-bodied worm-like animals. Slugs have no shells and snails have coiled shells. They leave silvery trails along the amaryllis's leaves after ravaging large holes in them.

2. Notice grubs in the soil by digging underneath the soil and finding white, brown, black, grey or yellow C-shaped insects. Because grubs eat plant roots, the damage often looks like cultivation problems and so can be hard to decipher. Amaryllis plants with grub infestations wilt and show nutrient deficiencies because their damaged roots cannot take up adequate water and nutrients.

3. Recognize wireworms by the damage on the amaryllis bulb, which exhibits stunted growth or lack of germination. These amaryllis pests are yellow to reddish-brown, segmented larval worms of click beetles.

Control Soil Pests

1. Use copper strips around the amaryllis' pot or as edging to keep snails and slugs away. The copper creates an electric shock when the pests' mucous coating comes in contact with the copper, preventing the pest from crossing over the barrier.

2. Purchase predatory ground beetles from specialty gardens stores. These species voraciously feed on soil-dwelling pests, like slugs, snails and wireworms that damage amaryllis plants. They live for two or three years and lay eggs in the soil that hatch into larvae that also feed on soil pests.

3. Dust diatomaceous earth (DE) on the base of the amaryllis to kill soil-inhabiting pests. The DE kills pests by draining all the moisture from their bodies and dehydrating them.

4. Release beneficial nematodes, such as Steinernema carpocapsae and Heterorhabditis heliothidis into the soil for quick control of the amaryllis soil pests. These microorganisms are available for purchase at garden stores and actively seek out insect hosts. After entering an insect, the nematode sheds its protective coating to release a intestinal toxin that kills the pest. It then leaves the host's body in search of a new one. Keep the soil moist to accommodate the nematodes.

Tips & Warnings

• Don't confuse garden variety DE with the type used in pools. Pool-type DE is ineffective on garden pests.

• Wear a mask when applying DE because it can irritate the mucous membranes.

References

• The Organic Gardner's Handbook of Natural Pest and Disease Control; Fern Marshall, et al.
• Garden Bulbs for the South; Scott Ogden
• Rodale's Complete Garden Problem Solver : Instant Answers To the Most Common Gardening Questions; Delilah Smittle
• Pests: Organic Gardening Basics Volume 7; Christine Bucks