welch] water insects ■ 141 



cial methods for each. These special methods will be given in 

 connection with each species in the discussion which is to follow. 

 However, a few general instructions will be given which will 

 apply to all aquatic insects and which will enable the beginner to 

 start his collection. 



Necessary Collecting Apparatus. 



The following articles will be needed : 



1. A suitable water net. 



2. Cyanide bottles. 



3. Tight tin boxes for living specimens. 



4. Quart jars, with tops, for living specimens. 



5. A common garden rake. 



6. Rubber boots (useful but not absolutely necessary). 



1. The Net. 



Any water net will do if it be strong and durable. The writer 

 has found the following described dip net to be very useful in 

 general aquatic collecting: The net is of about equal width and 

 depth, made of fine material of about one millimeter mesh like 

 fine bobinet and attached to the ring by means of strong muslin, 

 The ring is made of a one-fourth inch iron rod bent in the form 

 of a semicircle and firmly fastened to a long handle, the straight 

 side of the ring being opposite the point of attachment. 



2. The Cyanide Bottle. 



This killing bottle is made as follows: Put a few small 

 pieces of cyanide of potassium (buy at a drug store or from a 

 drug company) in the bottom of any wide mouthed bottle ; cover 

 with a layer of sawdust ; then fit a piece of perforated card board 

 on the top. Moisten slightly and keep corked. Be careful in 

 handling cyanide of potassium; it is a deadly poison. 



How to Use the Net. 



1. Put the net down into the water ; move it along with the 

 mouth open in the direction of the motion. This process is called 

 "sweeping." Make some of the sweepings on the surface, some un- 

 der the surface, some among the submerged or partly submerged 

 water plants, some on the bottom, and some into the bottom so 

 as to get the insects which are to be found in these diflferent places. 



2. When bringing up a net load of debris from a sweeping 

 of the bottom, wash out as much of the dirt and trash as possible 

 by scooping up the clear water with the net and letting it drain 

 through. This makes it easier to examine the catch especially 



