Thursday, 26 May 2016

Weekly Update (May 25, 2016; Wk 04) - Pea leaf weevil

Pea leaf weevil (Sitona lineatus) - Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight.  Adults are slender, greyish-brown measuring approximately 5 mm in length (Figure 1).
Figure 1. The pea leaf weevil, Sitona lineatus, measures ~5mm long (Photo: H. Goulet).

The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) yet the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen (Link here for the Pea leaf weevil monitoring protocol with photos of related weevils).  All species of Sitona, including the pea leaf weevil, have a short snout.

Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge (Figure 2).  Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.

Figure 2. Feeding notches on clam leaf of pea plant resulting from pea leaf weevil (Photo: L. Dosdall).