172 Annals Entomological Society of America [Vol. XIII, 



between microlepidoptera and the macros appears plainly and 

 has greater biological significance than the division into moths 

 and butterflies. 



The members of the first half of the order, the microlepidop- 

 tera, show the anomalous condition of greater variety of habitat 

 and food supply, associated with a most extraordinary uni- 

 formity in structure (excepting in leaf miners). Nearly all the 

 exceptions to rules occur in this group. In the more specialized 

 suborder on the other hand, one finds remarkable uniformity 

 in habits and food but a great variety of superficial appearance. 



The two most common forms of protection in Lepidopterous 

 larvae are (a) the development of tufts of setae and (b) the con- 

 struction of a nest or case. Silk glands are of universal occur- 

 rence but are used in many different ways with different results. 

 The effective value of tufted setas against birds, parasites, and 

 predators is well known. 



LIFE CYCLE. 



Leaving these general considerations of lepidopterous devel- 

 opment, a brief statement on the length of the life cycle should 

 be included in a paper on this subject. Typically the life of a 

 lepidopterous insect consists of (a) an egg stage, the egg simple 

 in structure and seldom concealed; (b) the larval period, of 

 five to seven instars; (c) the pupal condition, protected by a 

 cocoon, or, in form, a chrysalis; and (d) the adult relatively 

 constant in structure, and various in appearance like the larva. 



The number of broods is limited, Table III showing the 

 conditions in economic species in the northern States. One or 

 two broods a year are the rule, longer or shorter life cycles being 

 exceptional. The writer is familiar with no cycles longer than 

 one year outside the family Cossidae. 



More than three annual broods occur only in the southern 

 states or under conditions where breeding throughout the year 

 is possible. Seven broods in one year in a species living in grain 

 (Angoumois grain moth) seems to be the maximum authentic 

 record. 



The winter is usually spent as a larva, often followed imme- 

 diately by the pupa in the spring without resumption of feeding. 

 This is true in both one and two brooded species. In some 

 single-brooded forms the egg stage is the hibernating condition 



