METHODS OF COLLECTING INSECTS 333 



insects from escaping. An improved form of this net consists of an 

 outer sack with square in place of tapering bottom, the sack to be 

 made out of cheesecloth, cotton cloth, or some such material. On 

 the inside of this is fitted a short, funnel-shaped net made out of 

 bobbinet or light cheesecloth. This net has an opening of about 

 two inches at the bottom. In sweeping, the insects pass down 

 through this opening between the two nets and are unable to es- 

 cape. In this way great numbers of grass insects may be collected 

 without stopping to remove them from the net. The insects may 

 be stupefied by placing the entire net in a pail together with a piece 

 of cotton saturated with ether. 



For aquatic collecting certain other types of nets are desirable, 

 although the ordinary insect net may sometimes be used to 

 advantage. 



Water dip net (Fig. 468). The frame of this type of net is usu- 

 ally flattened on one side so as to allow the net to be manipulated 



FIG. 468. A water dip net FIG. 469. A small dip net 



(After Packard) (After Howard) 



closer to the bottom. The net itself should be made of fine brass- 

 wire netting, about twelve inches in diameter and of about the same 

 depth. Fig. 469 shows a dip net with a flange, or lip, of tin or 

 sheet iron, which is useful in dislodging aquatic larvae or insects 

 from around stones, thick weeds, etc. 



The sag net (Fig. 470). This form of aquatic net is described 

 by Professor James G. Needham, who is probably our best authority 

 on aquatic insects, as follows : 



It consists of a ring of stout spring wire three to four feet in diameter, to 

 which is attached a very shallow bag of bobbinet, and at one side is a handle 

 only long enough to be held readily. It is intended to catch insects adrift in 

 the stream, and is accompanied by an instrument for dislodging them. Such 

 an instrument is figured below the net. It consists of a handle three or 



