Integrated Pest Management Guide

LADYBIRD BEETLES (COLEOPTERA: COCCINELLIDAE)

Ladybird beetles are among the most familiar beetles occurring in British Columbia. Their often bright colouration - red or orange with black spots - advertise their "bitter" taste to possible predators. The female beetle deposits her yellow-orange eggs in clusters of 10 - 50 on foliage near a food supply. The emerging larvae are elongated and spindle-shaped. They often are brightly banded in patterns that identify the species.

Larvae do not resemble adults and are easily seen on cranberry foliage or on weeds in the beds. A full-grown larva can consume about 50 aphids in one day. An adult female needs up to 100 aphids before reproducing and will feed on approximately 2000 aphids in her lifetime, which can last 1-2 months during the warmer seasons. Adult ladybird beetles are very mobile and actively search for food. They are attracted by large numbers of aphids and increase their reproductive rates accordingly - up to 100 eggs per female. It takes 20 - 35 days for an egg to develop into an adult. British Columbia experiences 2 - 3 generations per year depending on the weather.

Ladybird beetles are predaceous both as adults and larvae. They prey mostly on aphids and on young scale insects. The larvae have also been observed to feed on small caterpillars like blackheaded fireworm as well as on each other. In cranberry beds, ladybird beetle larvae have been seen attempting to pry open fireworm tents using their legs and mandibles. Ladybird beetles ( Coccinella californica Mann.) have been observed feeding on fireworm larvae in Washington (Plank 1922). Ladybird beetles are often found overwintering in large swarms of adults under leaves and debris or in buildings, emerging again in spring.
 
 

Ladybird beetle	Ladybird beetle larva eating fireworm larva

Reference

Plank, H.K. 1922. The blackheaded fireworm of cranberry on the Pacific coast. Bulletin of the United States Department of Agriculture #1032.

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