PROCESSIONARY CATERPILLAR (Latin name Thaumetpoea Pityocampa) Also known as the tent caterpillar or pine caterpillar
The month of February is when these caterpillars are at their most active and dangerous stage of their life cycle, From December right through to early April they are very noticeable in the pine trees by their visible tent nests, often confused with spider nests or, from a distance, even small polythene bags and pieces of paper. This month is an ideal opportunity to write and allow us to have a greater understanding of these creatures and their life cycle.
These creatures are commonly, and locally, know as the pine processionary caterpillars, and have been researched as far back as the seventeenth and eighteenth centuries, mostly found in the warmest areas of southern Europe and North Africa. Their fame derives from the way they crawl over the ground in a long head-to-tail procession, (which can achieve a total length of up to ten metres plus, containing hundreds of caterpillars).
Protected by a sole defensive system that has the ability to sting anything that can cause them an immediate threat, their bodies release a perfusion of microscopic poisonous floating hairs into the air, and if contact is made with the skin or eyes will result in an irritating red rash, severe pain, swelling and possible shock.
If contact to the eyes, or signs of shock are apparent, immediately visit the doctor or the nearest hospital, anti histamine tablets are very good as first aid, on the spot, treatment.
Animals, as well as humans, can and do suffer from these hairs. Dogs are at the greatest risk especially when in pine tree forests with their natural instinct to go around along the ground sniffing. It is most essential, and cannot be over emphasized that brushing the caterpillars off, hitting them, or even tree branches, with any object is very, very dangerous as the poisonous floating hairs will keep discharging even if the caterpillars have recently been killed.
The procession caterpillar is most notorious for the destruction of pine forests, and is capable of defoliating hectares of pine trees in one season. Amazingly these caterpillars are only active at the cooler time of the year and in the cold winter months are thriving sustaining temperatures down to sub zero. At the other extreme, in the hot summer months, they are under ground in their pupa stage.
Around the month of August the moth starts to emerge from the ground and soon finds a partner where together they seek a pine tree to lay their eggs. An average female can produce a sole egg mass containing up to three hundred eggs. The egg mass is secured and fastened to the needles of the selected pine tree and the individual eggs are covered with very small scales by the female.
Immediately after the caterpillars are hatched, and despite their minute size, they soon start nibbling and cutting through the pine needles to create and construct several temporary shelters/tents by spinning silk thread around several pine needles. Soon, but at a later stage of development, they construct a main central permanent nest of layers of woven silk, which has no opening at all; the caterpillars just force their way in and out through the layers.
Throughout the cool and cold months of winter they emerge in colonies from their shelters soon after sunset and crawl to new feeding areas on the host tree. Whilst crawling over the branches undeterred by the cold weather they lay down a trail of silk to mark their pathway, not only for identification but also to assist in greater grip on the smooth needles. Caterpillars can distinguish their own trails as well as new from old. These trail marks also help to find the feeding areas and more so their way back to the main tent nest. The caterpillars normally crawl in small line groups, but each can move independently making the marking most important.
Overnight they feed on the pine needles and defoliate the pine trees before returning to their tent nest before sunrise and the daylight begins. The main central nest is very cleverly situated on the tree to take full advantage of the heat from the sun to keep the nest very warm. All through the day the caterpillars rest in this high temperature, thus allowing them to digest the food they savaged throughout the dark hours.
By March the caterpillars are fully established and start to leave their tent nest, they follow each other in this long head-to-tail procession along the branches, down the trunk and over many, many metres of ground away from the host tree to find a suitable location in the soft soil where they can burrow down to bury themselves and create a cocoon. Here they will stay until next August when the cycle will start again.
WARNING
Please do take care on the removal of the tent nests from pine trees. One method is to spray the entire tent nest with hair lacquer (ask first!). This is to seal the nest and prevent the defensive hairs exploding or, as a last resort, carefully slide a polythene bag over the offending branch, seal the end and remove the branch with some pruning shears. If in doubt do both of the above together. Once the tent nest is removed and on the ground you can carefully set it alight in a safe place to avoid any fire from spreading.
As previously mentioned about the explosion of floating hairs – if the caterpillars are crawling on the ground DO NOT just sweep them up, spray them with hair lacquer first to prevent the floating hairs being discharged.
Article coutesty of Stephen Padley (Landscapers & Constructors)