The species Epilachna varivestis, commonly known as the Mexican bean beetle, is a common pest to dry bean crops across Canada. The pest will feed in the larval and mature leaves, flowers and growing pods of the bean plants. However, the larvae often cause more damage than the adult form, as the larvae feed more voraciously.
The Mexican bean beetle larva is a dark yellow insect, with six rows of black tipped spines running along their back. The adult looks similar to a lady bug, about 6 mm in length, with small black spots on their back. The majority of damage will be seen on the leaves, but flowers and pods may be damaged as well. Entire leaves can be consumed, except for leaf veins.
When scouting for the Mexican bean beetle in seedlings, look for adults feeding. Economic threshold is divided into stages of growth on the basis of the number of insects per four row feet required to justify chemical control measures. Seedling: look for 3 or more adults. Prebloom: look for 20 or more larvae, plus the presence of 10 mature beetles. Bloom: look for 16 or more larvae and/or adults. Pod set: look for 16 or more larvae or/and adults.