365 



johansenni, Vier., on Phthorimaea operculella, Z. [R.A.E., A, x, 86]. 

 The method of parasitism and feeding by H. brevicornis, Wesm., on 

 its host, Pyrausta nuUlalis, Hb., is described in detail, and differs 

 Uttle from that referred to above, except that the construction of a 

 suction tube has never been observed, the parasite apparently absorbing 

 directly the body juices of the host. Experiments were then made 

 with adults of H. johansenni, provided with larvae of P. operculella 

 and also those of an unidentified Microlepidopteron living on Lavandula 

 stoechas. In each case the larvae were either used before spinning 

 their cocoon or else were removed from the cocoon, and in no case 

 was the construction of a connecting tube attempted ; the parasite 

 fed directly on the body of the host. The construction of the tube 

 is therefore connected with the presence of a cocoon around the larva, 

 but whether there is a change of instinct in the absence of the cocoon, 

 or whether the tube is omitted for merely mechanical reasons, is not 

 clear. 



Mason (A. C). Life-history Studies o£ some Florida Aphids. — Florida 

 Ent., Gainesville, v, no. 4, April 1922, pp. 53-59, 62-65. 



Recent experimental work tends to show that true sexual forms 

 in Aphids are produced only when conditions are not favourable to a 

 continuance of adult life. Attempts have therefore been made with 

 several species to continue rearing throughout the winter in order 

 to determine whether any sexual forms occur. Myzus persicae, 

 Sulz., is a very common and destructive species in Florida, being 

 found at all seasons of the year except the summer months. It feeds 

 on practically any young tender plant growth until about June, and 

 later disappears entirely, though small numbers probably continue 

 to live unnoticed on wild plants. An attempt to rear this species 

 in jars in a greenhouse had to be abandoned late in April owing to 

 fungous disease and extreme heat causing the Aphids to die off, but 

 during the winter no tendency to oviparous reproduction was seen. 

 Both winged and apterous females continued to breed partheno- 

 genetically throughout the winter, the average age of the female when 

 the first young were produced being 1 1 days, number of offspring being 

 27, and average length of life 17 days. This would allow nearly three 

 generations a month as the maximum rate of reproduction. During 

 the next winter, breeding was carried on in the open-air insectary. 

 In these conditions reproduction began at the age of 15 days on the 

 average, so that two generations a month would be the maximum 

 number. The average length of the whole life was about 36 days, 

 the productive period being 18 days and the approximate number of 

 young 43. No males or sexual eggs ever appeared. The fungus, 

 Eniomophthora aphidis, probably accounts largely for the apparent 

 disappearance of the Aphids during the summer, and seems to be \ 

 peculiar to this species. The Hymenopterous parasite, Diaereius 1 

 rapae, Curt., two species of Syrphids, the lacewing, Chrysopa octdata, 

 Say, and the Coccinellid, Chilocorus bivulnerus, Muls., all destroy 

 numbers of them. 



Aphis gossypii, Glov. (melon aphis) is of great economic importance 

 in Florida and is very numerous, occurring in various forms on different 

 food-plants, of which about thirty are known in Florida. The Aphids 

 live on melons and other fresh plants during the spring and summer, 

 and then migrate to orange trees in the autumn, any interval after 

 the melon vines have disappeared being spent on wild plants. It is 



