1923 ENTOMOLOGICAL SOCIETY. 45 



colour of the prothorax from which it derives its name. The head is decidedly 

 dark and the wing covers dull black. 



The eggs are irregularly oval in outline with two sides flattened, and measure, 

 on an average, from 1 to 1.5 mm. across. They are dirty- white in colour with 

 brownish edges, of soft shell, and are deposited either singly or in groups of 

 from two to six, at the axils of the branches, being inserted chiefly between the 

 outer and inner bracts close to the main stem. Hatching begins in three weeks. 

 The young larva on emerging approximates 1.5 mm. in length, is dull white in 

 colour and flat headed. It always enters the branch from beneath the egg, 

 usually at a point near the centre, although 25 per cent, of the larvae leave at 

 the edge. The empty case is made the receptacle for the first borings, which 

 are of very fine brown dust. After working spirally around the branch, the 

 larva continues on to the main stem of the plant, which it tunnels two or three 

 times in the outer bark tissues before entering the pith. This girdling work 

 causes the stem at this point to crack longitudinally in many places, producing 

 an elliptical swelling, commonly known as gouty-gall and results in killing the 

 branch the following year. Once the pith is entered, the tunnel becomes straight- 

 ened out and is packed with castings and the larva proceeds to bore upwards. 

 It attains a length of 16 to 18 mm. and is a flat, slender, white, legless grub. 

 Winter is passed in the stem and pupation occurs in May in a specially enlarged 

 cell. The adult then gnaws its way to the surface and escapes through an exit 

 semi-lunar in shape. The tunnels vary considerably in length, from three to 

 six inches or more. 



Cutting out the galls in spring and destroying them is a simple and ready 

 method to control this pest. Do this soon after the leaves appear. 



Agrilus politus Say. This species is of less importance economically than 

 ruficollis. It is a serious enemy of the hazel (Corylus), and does much injury 

 by forming ugly, knot-like galls on the branches, killing back all attacked parts. 



The adult is more robust, less trim in outline, and somewhat shorter than 

 ruficollis, averaging about 6.5 mm. in length and 2 mm. in breadth, and is of a 

 dull, uniform bronze colour, the tips of the wing covers being forked. 



The eggs are oval in outline, of soft shell, shiny, transparent white in colour, 

 and each about 1.5 mm. long and half as wide. They are laid singly and in 

 small groups of two or three, and covered afterwards with a protective secretion 

 which hardens into a capsule, brown in colour of a shade a little lighter than 

 the bark, being quite conspicuous scale-like objects on the branches. The 

 female, in laying, appears to have no special choice of location, and will deposit 

 a group of eggs near the axil of a small shoot, another group beside a raised 

 portion of bark or lenticle, and others quite often upon the clean, exposed bark 

 surfaces. This habit differs from ruficollis in that the last mentioned tucks its 

 eggs safely behind the bracts at the axils of the branches. The period of incuba- 

 tion requires approximately three weeks, hatching beginning about July 20th. 

 •The larva eats its way out at the smaller end of the egg, without disturbing the 

 capsule and enters the bark beneath, expelled frass being packed away into the 

 empty shell case. Several groups were under observation, and it was found 

 that the larvae left at the same end of each egg and bored, side by side in the 

 same direction, for 7 to 10 mm. lengthwise of the twig; then branching out 

 began to tunnel around the twig, near the surface, each circuit being close to 

 the previous one. The branch is consequently completely girdled. This 

 action sets up an abnormal stimulation of growth, cracking the outer bark sur- 

 faces and producing ugly, knot-like swellings or galls, eventually killing the 

 branches affected in this way. 



