THE CANADIAN ENTOMOLOGIST. I 8 D 



and Parcctopa Clem, (which is a Graeittaria), which seem to me to be 

 nearly related to each other, I have not yet found it so. For instance, 

 take L. robinietta Clem. It hybernates beneath bark, and is found abroad 

 on the wing, early in Spring, (so early that there are no flowers, and I can- 

 not imagine what it lives on) and in Summer. But the mine and larva, are 

 not found until the middle of July, (and then, and always, only in the 

 older leaflets ; I have never found them in young and tender leaflets). It 

 remains in the larval state, not exceeding three weeks, and in the pupal state 

 not so long. Six weeks will cover the time from the hatching of the egg to 

 the development of the imago, at which period many of the old brood 

 still remain alive ; and from that time, until the fall of the leaves in 

 Autumn, the insect may be found in all its stages, and in gradually in- 

 creasing numbers in all. Many are still in the larval state, when the leaves 

 fall, and doubtless perish. Others survive as pupae probably; as do other 

 non-hybernating species. L. robinietta is the only Lithocottetis which I 

 know to hybernate, though I suspect that Z. salieifoliella also does, from 

 the fact that I have found it abroad late in October. Of the allied genera, 

 all the species of Phyttocnistis known to me, winter over as imagines, except 

 P. Uriodendronetta Clem., and, perhaps, that does also. All the others, so 

 far as I know their habits, pass the winter as larvae or pupae. They begin 

 to appear sometimes as early as March, usually in April, and towards the 

 latter part of May they begin to oviposit. From the first to the middle of 

 June, the first pupae are found, and, shortly afterwards, the first imagines, 

 whilst yet their ancestors are still alive ; and from that time, until the fall 

 of the leaves, they may be found in constantly increasing numbers, in all of 

 their stages, and the different broods overlap, so that there is no line to 

 be drawn between them. 



But, if the phrases " spring brood/' " summer brood," &x., only mean 

 that there is a certain number of generations descended from a given pair 

 in one season, then we can only arrive at the number of generations, by 

 breeding them, or by guesses, founded on the length of time, passed in the 

 larval and pupal states. I write about one degree south of Dr. Clemens, 

 and I think it probable that there are as many as four here, and certainly 

 not less than three ; and the number increases as we go southward. I 

 have taken Z. Ulmella, or a closely allied species, at Columbus, Georgia, 

 late in November — a month after it had disappeared here. And I have 

 found Parectopa robinietta Clem, actively mining Locust leaves at New 

 Orleans in December ; and if there is any cessation of its broods there at 

 all, it can not exceed two months. 



