lo FIRST LESSONS IN ZOOLOGY 



countr)-, though unfortunately there are but few now. 

 The author \\ ill be glad to send * a few eggs, say 

 twent}'-five, once to an)' teacher who will defray the 

 cost of postage. From the first lot of eggs moths 

 may be raised and new eggs obtained, and a gen- 

 eration thus be reared each year. There are four kinds 

 or races of silkworms, one of which, known as annuals, 

 produces but one generation a year, the second kind, 

 called bivoltins, produces two, the third, the trivoltins, 

 produces three, while the fourth, found in India, produces 

 six or seven generations each year. The eggs which the 

 author can furnish are those of the annual race, and will 

 naturall}' hatch in the Middle and Eastern States from 

 April 15 to May I. By keeping them at a temperature 

 of 40" F., or below, the hatching may be postponed as long 

 as desired. Under no circumstances should it be allowed to 

 take place before the first mulberry or osage orange-leaves 

 appear in the spring. If it is more convenient to rear the 

 silkworms in the fall, the eggs may be kept in some re- 

 frigerator or cold-storage room through the summer. But 

 the natural hatching-time will be found to coincide fairl}- 

 with the leafing of the mulberry and osage-orange trees, 

 and no special care in keeping will be necessary. As the 

 silkworms will feed on no other than mulberry or osage- 

 orange leaves, a supply of these must be available, or 

 some other motli chosen for this life-history stud}'. How- 

 ever, both these trees are spread over the whole countr)', 

 and one or the other is to be found in nearly every locality. 

 The advantage of using the mulberry silkworm moth for 

 this life-history study lies in the " domesticity" of the in- 

 sect ; the worms have no tentlency to crawl away but 

 will remain quietly in open shallow tra)'s as long as food 

 is provided them, and the moths, although winged, do not 



* Addrrss V. I,. Kellogg, Stai.t.ir.l Uuivi-rsit)', Calilornia. Srn.l Hve 

 cents in stamps for postage. 



