|The monarch caterpillars feeding on the new milkweed plants I got at Home Depot all died. Caterpillars on other milkweed in the same garden thrived and became butterflies. Are these plants Home Depot sells as|
Nursery plants are not usually sprayed with pesticides prior to sale so I don't think there's a residue on your Milkweed plants. Insect pests such as female thrips and predacious wasps can kill monarch larvae by puncturing their skins and that might be what is happening to your monarch larvae. Inspect the milkweed for thrips and for aphid populations. Aphids will attract tiny wasps which lay eggs in the aphids. If you see aphid mummies (hard shells that look like swollen aphid), predacious aphids are active in your milkweed. I'd rinse the plants off with water from the hose to dislodge any insects. Hose them off every day for the next few days and they should be free of insect pests. Hope this information helps you determine just what might be going on with your butterfly larvae.