[12] REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



As the earlier broods did not fall under my observation, tliere may be a question as 

 to their number, but the season of 1880 being an early one, it is probable that the first 

 brood was no later in making its appearance than in former years, when grown worms 

 were seen early in May. In this case the first brood will have begun in April. The 

 two larva3 found by Mr. Roberts on June 5, and which pupated on the following day, 

 will then fall into the second brood ; and the moths appearing about the middle of 

 the month, an interval of thirty days remains to be occupied by the third brood. 

 During this period the eggs were scattered over the entire plantation, and as their 

 deposition was probably continued many days, the succeeding generatiojis became 

 confused. 



The past season has been hot, and with an unusual amount of rainfall, ])articularly 

 during the month of August, conditions which are usually regarded as favorable to 

 the development of Aieiia, and unfavorable to enemies, but which at Centreville do 

 not appear to have hindered in the slightest degree the spread of certain parasites — 

 notably the minute egg parasite (Tricliogramma). 



My observations upon the egg of Aletia simply confirm what has been already noted 

 by other observers, and I have not thought it of advantage to multiply tables which 

 would give results not differing materially from those shown in the one already pro- 

 duced. I found the eggs almost invariably deposited on the under side of the leaf, 

 often close to but very rarely upon a vein. Exceptionally they were found upon the 

 upper surface of a leaf, and in one or two instances upon the involucre of a flower. 

 In July an undue proportion appeared to be deposited upon axillary leaves, L e., 

 those growing upon the main stalk, in the axils of branches. Such leaves are often 

 aborted in size, have smooth surfaces, and, though very mature and tough, are seldom 

 rusted or infested with plant lice. They appear to afford the most favorable food 

 material to the very young larvae. The middle third of most plants bears the great- 

 est number of eggs, although the lower leaves, even when much sanded, are often not 

 disdained by the mother moths. These, as a rule, deposit but one egg upon a leaf; 

 rarely two appear to be laid upon the same leaf by a moth, in which case they are 

 found close together, and were probably deposited simultaneously. Upon leaves 

 marked for special observation I have had three eggs deposited during the same night. 

 The number found upon a single leaf will depend upon the abundance of moths, the 

 condition of the plants, &c. I have never observed more than seven unhatched eggs 

 upon the same leaf. Eggs are laid during the first part of the night and early morn- 

 ing. I believe few are deposited between midnight and 2 o'clock a, m. In the period 

 of incubation I found little variation ; the young worms appeared on the fourth day, 

 seventy-two to eighty-four hours from the laying of the egg, hatching usually in the 

 early morning. The young worms appear upon the outer or upper leaves of the plant 

 when nearly half grown. 



Only green worms were seen until the fourth brood was well advanced, in the lat- 

 ter part of July. Worms with dark stripes then appeared, and gradually became 

 more numerous, until at the close of the fourth and throughout the fifth brood they 

 outnumbered the green worms. Numerous tests failed to show any difference in time 

 of development between the two forms. The worms were seldom 'seen feeding at 

 night, and only on bright moonlight or starliglit nights. Many specimens were, how- 

 ever, bied from the egg to the moth in tight tin boxes, and this exclusion of light 

 appeared to have no effect ui)on the coloration. Of those fed upon immature leaves 

 a greater proportion remained uniformly green ; but the experiment was not conclu- 

 sive, as not a few of those fed upon mature leaves remained equally light-colored, 

 while dark forms occurred in all my breeding-boxes. I was unable to find the worms 

 feeding upon other plants than cotton, either in the cultivated fields or woods in the 

 vicinity. Although I sometimes failed to observe more than three or four molts, a 

 variation from the normal number, five, was never satisfactorily made out. 



It is often asserted by the planters that cotton in the shade of trees is not eaten by 

 the caterpillars. My own observations upon this point gave conflicting results. While 

 in some cases I found cotton thus shaded entirely untouched, although the surround- 

 ing plants were mucli ragged, in other marked instances shade appeared to exercise 

 no protective influence. The following transcript from my notes gives one case in 

 point. It records the discovery of a brood center belonging to the fifth generation. 

 August 20: I learned to-day of a portion of the field where caterpillars were to be 

 found, and visited it. It is a small area of '' bottom land," bordering upon the road. 

 The cotton is somewhat ragged, and worms of all sizes are moderately abundant. 

 There are worms just webbing up and pupa? both vacated and living. Young worms 

 (one- third grown) are the most abundant, but eggs are scarce, and I saw but one or 

 two moths. This is evidently a center of the brood following that in the ''young 

 cotton," which is in the same field about a quarter of a mile distant. By the side of 

 the road, and covering a portion of this bottom, stands a very large oak tree, with 

 low, spi-eading branches, casting quite a dense shade. The tree has been girdled and 

 is slowly dying, but has not lost its leaves. The cotton rows under it are unbroken. 

 The plants standing close about its trunk are very tall and rank, with large and fully 



