Insect Study 



393 



parasitized aphid enlarged, 



slioiuing the door cut by 

 the parasite. 



as long as there is left a leg, and apparently to the very last, never realiz- 

 ing "what is doing." But they are not without means of defence; those 

 two little tubes at the end of the body are not for ornament nor for 

 producing honey-dew for the ants, but for secreting at their tips a globule 

 of waxy substance meant to smear the eyes of the attacking insect. I 

 once saw an aphid perform this act, when confronted by a baby spider; a 

 drop of yellow liquid oozed out of one tube, and the aphid almost stood on 

 its head in order to thrust this offensive globule directly into the face of 

 the spider — the whole performance reminding me of a boy who shakes 

 his clenched fist in his opponent's face and says, "Smell of that!" The 

 spider beat a hasty retreat. 



A German scientist, Mr. Busgen, discovered that a plant-louse smeared 

 the eyes and jaws of its enemy, the aphis- 

 lion, with this wax which dried as soon as 

 applied. In action it was something like 

 throwing a basin of paste at the head of the 

 attacking party; the aphis-lion thus treated, 

 was obliged to stop and clean itself before it 

 could go on with its hunt, and the aphid 

 walked off in safety. The aphids surely 

 need this protection because they have two 

 fierce enemies, the larvae of the aphis-lions 

 and of the ladybirds. They are also the victims of parasitic insects; a 

 tiny four-winged "fly" lays an egg within an aphid ; the larva hatching 

 from it feeds upon the inner portions of the aphid, causing it to swell 

 as if afflicted with dropsy. Later the aphid dies, and the interloper 

 with malicious impertinence cuts a neat circular door in the poor aphid's 

 skeleton skin and issues from it a full fledged insect. 



The aphids are not without their resources to meet the exigencies of 

 their lives in colonies. There are several distinct forms in each species, 

 and they seem to be needed for the general good. During the summer, 

 we find most of the aphids on plants are without wings; these are females 

 which give birth to hving young and do not lay eggs. They do this until 

 the plant is overstocked and the food supply seems to be giving out, then 

 another form is produced which has four wings. These fly away to some 

 other plant and start a colony there ; but at the approach of cold' weather, 

 or if the food plants give out, there are male and female individuals 

 developed, the females being always wingless, and it is their office to lay 

 the eggs which shall last during the long winter months, when the living 

 aphids must die for lack of food plants. The next spring each winter-egg 

 hatches into a female which we call the "stem mother" since she with her 

 descendants will populate the entire plant. 



Plant-lice vary in their habits. Some live in 

 the groimd on the roots of plants and are very 

 destructive; but the greater number of species 

 live on the foliage of plants and are very fond of 

 the young, tender leaves and thus do great 

 damage. Some aphids have their bodies covered 

 with white powder or with tiny fringes, which 

 Winged and ivingless give them the appearance of being covered with 

 forms of plant-lice. cotton. 



