Lupine pests and blister beetles

Dr. Leonard Perry

University of Vermont Extension Horticulturist


Have lupines?  If so, how did they bloom this year?  If poorly or worse, chewed, perhaps they had one of the two main pests of lupines– aphids and blister beetles.  I heard of the latter here in Vermont for the first time this year.  The species (there are several dozen) seen here was distinctive with its elongated black body about an inch or so, and orange legs (Lytta saydi).  This beetle in the Meloidae family is a natural biological control for grasshoppers, feeding on eggs, and of ground bees.  In years with more grasshoppers, or regions such as the midwest, it can be more of a problem.  It is often listed as a pest on some field crops in the midwest such as alfalfa.  In home gardens it can also chew up other legumes such as the false indigo (Baptisia).  Luckily the blister beetle only has one generation per year.

A forceful hosing off with a stream of water every couple days may be all that is needed for either pest.  If using insecticides listing beetles (organic or synthetic), make sure and apply according to the label.  Spinosad and products containing neem are often seen recommended for these pests. If hand picking beetles, use gloves as they can secrete a toxic compound causing blisters (hence the name).

Many species of blister beetles produce cantharidin, a toxic compound similar in effect to strychnine. Yet this has been used since Greek and Roman times medicinally and as an aphrodisiac.  Such obviously is not recommended, and this is only used in limited applications by veterinarians.  The compound is in the blood of the insect as a defense mechanism if attacked, or is used by the female to coat the eggs for protection. 


1 Comment

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One response to “Lupine pests and blister beetles

  1. Chantelle

    In my experience, a strong jet of water on lupine aphids serves only to blast the aphids away from the plant, after which they walk right back and start eating again. However, there should be enough time between blasting them with water and them returning to the plant for you to squish them.

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