40 



THE AMERICAN ENTOMOLOGIST. 



which development may be seriously checked if 

 the temperature here should be, as it probably 

 would be, much lower than the temperature of 

 England. Disease maybe thus induced; and my 

 opinion is that most of the failures occurring 

 here this last season may be attributed to this 

 cause. 



It will be perhaps remembered that the spring 

 of 1809, at least on the Atlantic coast, was very 

 backward. The consequence was that, when 

 on April 20th some of the Yama-mai eggs began 

 to hatch out, there was nothing worthy of be- 

 ing called an oak-leaf to be found for them. 

 The few warm days occurring at this time were 

 sufficient to complete the development of the 

 caterpillar, but not sufficient to make the neces- 

 sary advance in the growth of its food-plant. 

 Buds, rather than leaves, of Qiiercus coccinea 

 were however obtained, and upon these the 

 larvae fed a little. Still they were very sluggish 

 and inert, and the weather again becoming very 

 cold, most of this first lot died within the first 

 two days. Dr. Wallace recommends that the 

 larva; be removed, as they hatch out, to strips 

 of glass moistened with water so that they may 

 drink. A better plan is, I think, to remove 

 them at once to branches, the leaves of which 

 have been well sprinkled. Moisture in some 

 way should, I have no doubt, be furnished 

 them. 



By May 3d nearlj- all the caterpillars, amount- 

 ing to over a hundred, had died from the preva- 

 lence of cold. I was obliged to keep them 

 within doors, and they appeared to eat a little 

 during the day ; but they became torpid during 

 the night, and in the morning were all but in- 

 animate. The temperature had ranged from 

 ■too on April 2Gth to 58° on the 27th, and by 

 May 3d had gone down again to 35". 



By May 12th more eggs had ari-ived IVom 

 England, and the weather having become some- 

 what warmer, hatched out almost immediately. 

 These I fed on Q. coccinea and Q. tinctoria 

 indiflerently, the larva evincing, I think, a little 

 preference for the former, but doing well on 

 both. The branches were placed in water, un- 

 der a verandah facing the northeast, so that the 

 rays of the morning sun had access to them, the 

 larva; appearing to enjoy the warmth. I kept 

 them out night and day, unless the night threat- 

 cued to be very cold. In warm dry days I 

 sprinkled the branches two or three times with 

 Clearwater. A short description of tlio larvae 

 may not be out of place here. 



On hatching out they are brimstone \ ellow ; 

 the body sparsely covered with strong hairs. 

 After the second moult they become greenish, 



with black spots. After the third moult the 

 color is a beautiful apple-green, with yellow 

 tubercles on each segment, and a few black 

 hairs emerging from each tubercle. The head 

 and legs are chocolate brown, the pro-legs red- 

 dish. On the anal legs there is a dark brown 

 or nearly black patch. The first segment is 

 edged with deep pink. In some lights a silver 

 spangle appears on some of the tubercles. The 

 markings do not greatly differ during the re- 

 mainder of their growth, but the apple-green 

 color becomes, if possible, still more beautiful. 

 It is almost impossible to imagine weather 

 more unfavorable for the rearing of any foreign 

 insects, than that which prevailed in New York 

 during the months of April and May. I have 

 already noticed this, but it may bo well to quote 

 from the record a little farther. On April 26tli 

 the thermometer at 6 a. m. stood, as I said be- 

 fore, at 48"; at 3 p. m. it was 71°. On the 27th 

 it was 58'' in the morning and 72" in the after- 

 noon, while on the Suth the mercury scarcely 

 reached S.'i" in the hottest part of the day. On 

 the 2d of May it reached no higher than -11"', 

 keeping quite cold up to about the 22d, when it 

 ranged from 49" at 6 p. m. to 02" at 3 r. m. On 

 the 31st it reached as high as 79". Dr. AVallace 

 tells us that the temperature most favorable to 

 the welfare of the larvse is from 50" to GO" in 

 May and 05" to 75" in June, and thinks that a 

 higher temperature "endangers the safety of 

 the worm." Now, in June we had a series of 

 hot days, in which the mercury reached over 

 8(j". The consequence of all this was, that on 

 June 26th, out of about 200 larvre which had 

 been a few days before apparently thriving, 

 having reached their last moult, all but six 

 were dead. A few may have wandered, and 

 about three died of diarrhea, but the majority 

 died of a disease acting very rapidly, which 

 showed itself first in brown patches, generally 

 on the second and third segments, but which 

 soon afterwards extended over the whole body. 

 Dr. Wallace informs me that in England, this 

 year, Yama-mai has generally failed ; the larvae 

 dying of a disease displaying symptoms similar 

 to those above named. In some cases the larva 

 eats a little after the disease becomes manifest, 

 then suddenly stops, and a few hours after- 

 wards it is seen hanging down from its anal 

 legs a flaccid mass of corruption. A pale green 

 fluid has by this time escaped, generally from 

 between the first and second segments; and all 

 that remains of the once beautiful caterpillar is 

 an empty skin. 



Most of my correspondents have also beenuu- 

 forlunatc. In some cases the eggs hatched out 



