112 BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



Verdigris. — The acid juices in the bodies of certain insects have an 

 affinity for pin metal, so that when these specimens are mounted on 

 bright pins a green substance known as verdigris will accumulate 

 about the pin, finally corroding it so that it will easily break. Black 

 or japanned and silvered pins do not verdigris, and therefore are to 

 be preferred for many insects. In collections there are often speci- 

 mens which have been pinned with a white pin and later have verdi- 

 grised. If it is desired to save these they should be remounted with 

 black pins. This may be done by putting the insect for a day or two 

 into the relaxing jar; then pull out the pin and place the insect in 

 ether or gasoline, which will dissolve the grease and verdigris; then 

 clean and put in a new pin. It is claimed by some that ammonia will 

 dissolve and remove the verdigris. Aquatic insects and those whose 

 larva? live in wood are particularly subject to verdigris. Insects 

 saturated with salt water are also apt to corrode the common bright 

 pins. 



Grease. — Some insects have so much fat in their bodies or itds in 

 such a condition that in drying it spreads over the insect and out on 

 the wings. This is a common trouble with many moths. They can 

 be readily cleaned with gasoline or ether. Pin the specimen tightly 

 to a piece of cork which is fastened in a deep vessel, then fill up the 

 vessel slowly and carefully with gasoline until the specimen is cov- 

 ered. It may be left for two or three days, and when taken out and 

 dried in a place where there is no dust it will become as fresh and 

 clean as a perfect specimen. If only the abdomen is greasy this may 

 be broken off and put into the gasoline, and later glued to the thorax. 

 Sometimes it will be necessary to keep badly greased specimens in 

 the ether or gasoline a longer time, or to change to fresh gasoline 

 at the end of two or three days. 



The Denton brothers put papered Lepidoptera, papers and all, 

 into the gasoline and leave for two weeks; then take out and dry, 

 without removing the insects from the papers. When dry they are 

 fluffy and fresh as though never wet. Of course gasoline should not 

 be used when near a light. Collections of insects should be looked 

 over twice a year for pests, at least in a region where pests are at all 

 common. The dates will vary somewhat according to latitude, but 

 the best times will be in March or April in the spring, and again late 

 in August or early September. No one who really loves the speci- 

 mens he has collected and studied will fail to take proper care of 



them. 



REARING INSECTS. 



It has already been indicated that the best way to secure perfect 

 specimens of Lepidoptera is by rearing them from the immature 

 stages. Many entomologists, however, soon become interested in the 

 life histories of insects, and find the collecting and rearing of the 



